2001Mars Society Convention Part 5

Are There Sufficient Natural Resources on Mars to Sustain Human Habitation?Methane and Carbon Dioxide Hydrates as Raw Materials to Support Colonization

Robert E. Pellenbarg; Michael D. Max; Stephen M. Clifford[2000]

AbstractThere is a good possibility that long-term production of deep biosphere methane (CH4) has occurred on Mars. Resultantmethane would tend to rise buoyantly toward the Martian surface. This methane would have been captured over a longperiod of time and will now be stored in methane hydrate, which has the potential to concentrate methane and water.Both CH4 and carbon dioxide (CO2, a predominant gas in the Martian atmosphere) are stable as gases on the Martiansurface but probably lie within the hydrate stability field as vast resource deposits in surface-parallel zones that reachclose to the Martian surface.

In order for humankind to establish itself on Mars, colonies should become self-sustaining there as soon as possible.With hydrates of both CO2, (oxidized carbon, C, at +4 oxidation state) and CH4, (reduced C at -4 oxidation state), Marswould contain the basic elements for human habitation: fuel, potable water, and industrial feedstock in a near-surfacesituation suitable for controlled extraction. With the addition of nuclear- or solar-electric energy, the synthetic organicchemistry necessary to support human habitation on Mars is an exercise in miniaturized, innovative chemicalengineering. Instead of transporting fuel for the return journey and all the items needed for human habitation of Mars,optimized standard industrial chemical plants would be designed for operation on Mars in order to manufacture a varietyof plastic objects, such as shelter, habitats, vehicles and other apparatus, in addition to synthetic liquid high energy-density fuels.

Thus, identification and quantification of methane hydrate and carbon dioxide hydrate, or proof of their absence, mustbe regarded as one of the emerging questions about Mars which must be answered in order to allow for effectiveplanning and preparation for human travel to Mars. The actual presence of these hydrates may prove to be the key tocolonization of Mars.

IntroductionThe National Aeronautics and Space Administration (NASA) of the United States, along with other national andinternational space agencies, is planning for planetary exploration. Although this exploration is making use ofinformation-gathering robots at present, planning for human travel to the planets is under way. Mars should be the firstplanet selected for direct human investigation because of its relative nearness, the possibility that it once had, and couldstill have, life, and because surface conditions are within a range that present technology can provide for sustainablehuman habitats, at least for short periods. Any attribute of Mars that could be exploited to provide for longer-termhuman habitation and possible planetary terraforming in the future, however, is very important to consider at this time.Better knowledge about the natural resource base of Mars is fundamental to organizing both visits and colonization,much the same as any of the historical exploration that has been carried out on Earth. Where natural resources are variedand abundant, colonization has a greater chance for success. If most supplies and materials must be transported one-way to Mars, the planet may only be an outpost rather than a colony. To become a true, viable colony, human habitationon Mars must become self-sustaining as rapidly as possible. Indeed, if long-term habitation on Mars is to becontemplated, the atmosphere and surface of Mars must be remediated and the climate made milder.

Present conditions on Mars would seem to support a Stone Age existence. That is, the raw materials on the surface ofthe planet would appear to allow dry masonry construction, but little else. Materials science must be brought to bear toengineer materials that will allow implementation of the technology to permit colonists to prevail. Although there maynot be a wide variety of materials on Mars, what is there may provide a sufficient, but small, list of resources, presentin staggering quantities. Relatively basic chemical engineering can be used to convert these natural resources into the

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Robert E. Pellenbarg; Chemistry Division, Naval Research Laboratory, Code 6101, Washington DC 20375 / Michael D. Max; MDS Research, Suite 302, 1211Connecticut Ave. NW, Washington DC 20036; Stephen M. Clifford; Lunar and Planetary Institute, 3600 Bay Area Blvd., Houston TX 77058

materials to assure colonial success; if the colonists are bold and clever, and the course to human habitation of Mars hasbeen properly mapped and implemented by Earth-based agencies, then there is a high probability for success forpermanent human habitation of Mars.

Methane on Mars and its Potential SignificanceIf the early evolution of the Martian surface followed that of Earth, then abundant methanogenic bacteria were likelypresent in the aqueous environment of the young Martian surface. During the transition to the present cryogenic Martiancrust, this life would probably have adapted to deep biosphere form, along with existing deep biosphere, similar to thatwe now recognize in the warm, deep sediments and rocks of Earth. Deep microbial biosphere on Mars would almostcertainly also have been methanogenic, as it is on Earth.

Long-term production of deep biosphere methane, if it in fact occurred, has enormous implications for the potential ofhuman travel to Mars and occupation of the planet. If no significant deep methanogenic biosphere ever produced largeamounts of methane, then fuel and other basic requirements for human habitation would have to be imported. Ifmethane is available, however, the entire situation regarding the likelihood of human habitation of Mars becomesradically more favorable.

A mechanism for the long-term concentration exists on Mars as it does on Earth (Max and Lowrie, 1996). Biogenicmethane produced as a waste product tends to migrate buoyantly upward in pore water rock porosity until it reaches theHydrate Stability Zone (HSZ), which is a temperature / pressure region in which methane hydrate is stable. One m3 ofmethane hydrate contains about 164 m3 methane (Earth STP) and 0.87 m3 of fresh water. On Mars, the particularpressure-temperature and thermodynamic equilibrium associated with the cold Martian surface is favorable for theformation of a substantial HSZ (Max and Clifford, 2000).

Methane hydrate and water-ice form a mixed cryogenic zone in which water-ice is stable from the surface to about 0°Cat depth and hydrate is stable from some depth below the surface (depending on average surface temperature, totalpressure, and geothermal gradient) to some depth below the base of the water-ice stability zone. Under current ambientconditions on Mars, methane hydrate is stable close to, but not at, the surface. Since the dominant constituent of theMartian crust appears to be basalt (or basalt-derived weathering products), the difference in lithostatic pressure at anydepth between Mars and the Earth simply scales in proportion to the ratio of gravitational accelerations for the twoplanets (i.e., ~0.38 g). At the 200ºK average surface temperature of Mars, hydrate is not stable at less than about 140kPa (data in Sloan, 1997), which corresponds to a depth of ~15 m (assuming an ice-saturated permafrost density of2.5x103 kg/m3). Given a reasonable estimate of the thermal properties of the crust, the base of the Martian HSZ shouldthen extend to depths that lie from several hundred meters to as much as a kilometer below the surface of Mars. Thus,the total thickness of the HSZ on Mars is likely to vary from ~3 km at the equator, to ~8 km at the poles (Max andClifford, JGR-Planets, in press).

If concentrated methane in the form of methane hydrate can be found in the near subsurface of Mars, then all theelements necessary for the human habitation of Mars exist there. Altering the pressure-temperature conditions ofhydrate will release both abundant methane (held in a compressed form) and water simultaneously. Additional waterfrom occluded permafrost ice will supplement the water produced from dissociation of methane hydrate, but may notbe necessary.

Water, of course, is the most basic requirement for human habitation of Mars and it is likely that water (as ice) is presentin the Martian cryosphere. Water will support a human-supportive biosystem for both plants and animals, undercontrolled conditions. But other elements are required for a self-sustaining of human habitation. Oxygen and hydrogen(fuel) can be produced by electrolysis from the water using electricity produced either from small nuclear reactors and/orsolar power. Combustion of methane, however, produces both water and CO2 either in fuel cells or by high temperaturechemical reactions. This CO2, or gas from CO2 hydrate, would amend the atmosphere in enclosed biomes to beconstructed on Mars.

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Are There Sufficient Natural Resources on Mars to Sustain Human Habitation?

In addition to its utility as a fuel, however, methane is a basic hydrocarbon building block and is a primary feedstockfor the manufacture of plastics and other synthetics (including higher energy-density liquid fuels) from which virtuallyevery object necessary for human habitation of Mars can be manufactured. Existing chemical engineering technologycan be miniaturized, optimized for Martian conditions, and used to fabricate virtually everything necessary in-situ, onMars. This fabrication potential would be the final element required for the permanent human habitation of Mars. Fuelsfor returning to Earth and exploring further would be produced on Mars itself. The transport requirements to supporthuman habitation on Mars would be reduced by the ability to produce many, if not most, of the physical objects requiredon Mars, from Martian materials. The ability to produce pressurized habitats, clothing, vehicles, etc. with only theimport of a relatively small amount of specialized equipment or materials (e.g., chemical catalysts) from Earth wouldgreatly change the support economics and enhance the likelihood of successful long-term occupation of Mars.

The possible existence of methane hydrate in the shallow subsurface of Mars offers extraordinary potential to supportand sustain the human habitation of Mars. Thus, identification and quantification of methane hydrate, or proof of itsabsence, must be regarded as one of the key questions about Mars that must be answered in order to allow for effectiveplanning and preparation for human travel to Mars. Indeed, the question of availability of methane hydrate on Marsmay prove to be the key to human occupation of Mars.

“Mining” HydrateMining carbon and oxygen compounds on Mars will follow techniques being developed for recovering gas and waterfrom hydrate on Earth where the newly recognized methane hydrate resources in permafrost and oceanic environmentsconstitute an emerging major energy resource (Max, 2000).

From the outset, recovery of methane or carbon dioxide from hydrate will require application of secondary recoverytechniques because the hydrate is present in the form of solid permafrost hydrate. Methane recovery from hydrate willinvolve forced dissociation. In addition, knowledge about the dispostion of hydrate in the Martian cryosphere isrequired before recovery scenarios can be envisaged; comparison with permafrost hydrate on Earth provides only a firstorder estimation of hydrate disposition on Mars because of the profound differences in geological and biologicalattributes. On Earth, hydrate is most stable in the upper part of the HSZ and least stable near the HSZ base and recoveryscenarios usually target the base of the HSZ (Max and Chandra, 1998; Max and Dillon, 1999). On Mars, where the baseof the HSZ will likely occur below the water-ice cryosphere (Max and Clifford, 2000), this may be found at aconsiderable depth. Because drilling capability on Mars will be limited initially, shallower hydrate deposits wouldprovide the first drilling and recovery targets.

Methane can be derived from hydrate by melting the hydrate. This melting can be accomplished in three major ways.Firstly, heat in the form of hot water or steam can be applied directly to the buried hydrate through drill holes. Thistechnology is well known to the hydrocarbon industry and is often used with heavy oils. Secondly, hydrate can bedecomposed, by altering the position of the hydrate stability phase boundary via introduction of inhibitor fluids containingsuitable dissolved ionic material, which functions similarly to antifreeze and lowers the melting temperature. Thirdly,dissociation can be induced where hydrate is present close to its pressure-temperature limits of stability where free gas isin contact with the hydrate. Lowering the pressure in the gas deposit will cause hydrate in contact with the gas todissociate, drawing heat from the environment. It is likely that commercial recovery of methane from hydrate on Earthwill use a combination of the three methods, optimized for the characteristics of individual deposits, and lessons learnedhere can be applied on Mars. The closer the pressure-temperature position of the hydrate body is to the stabile phaseboundary, the less thermal energy needs to be introduced or the less chemical inhibitor is required to cause dissociation.

Both hydrate and associated gas deposits of methane and carbon dioxide may prove to be recoverable resources on Mars.Permafrost hydrate deposits will be capable of holding considerable gas pressure because of the strength of the boundinggeological rocks and regolith. Thus methane hydrate deposits on Mars are likely to be similar to conventionalhydrocarbon traps on Earth, for which both natural occurrence and methods for recovery are well understood. Recoveryshould be possible using modified conventional drilling and recovery technology.

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Little is now known about the subsurface character of the Martian geology. Virtually nothing is known about thelikelihood or location of structural or stratigraphic traps, or their Martian equivalents. The sedimentary and lithicmaterial from which the upper strata of Mars is composed is also poorly characterized. Nonetheless, the cryosphere onEarth exhibits many features that could be important to providing pathways for gas accumulation and migration, whichare vital to recovery of significant volumes of gas on Earth, and provide further insight to the parallel situation on Mars.In addition to primary porosity extensive secondary porosity in the form of faults, fractures, and ‘frost heaving’ volumechanges owing to ice and hydrate formation may produce pathways for fluid and gas migration in rocks that areotherwise too tight to allow significant internal flow. Extensive faulting has been observed in gas hydrate bearing stratain many areas, and the faults show evidence of fluid flow (Dillon et al., 1998). Where gas will not spontaneously flow,mechanical fracturing (fracking, a standard procedure used now on Earth) is also possible on Marsh, but this approachwould introduce additional operational problems and requirements.

Chemical Opportunities and Constraints on MarsThere is no question that the Martian atmosphere contains CO2, (C, at +4 oxidation state) albeit at very lowconcentrations. It is highly likely that CO2 hydrate also occurs on the planet. Thus, Mars possesses fixed, but oxidized,carbon. If, as seems increasingly probable, the Martian crust contains CH4 (C at -4 oxidation state) trapped as hydrate,the planet would thus also posses fixed, reduced carbon. In addition, CO2 and CH4 hydrate concentrate fixed carbonand water (H2O) at the same place. These chemically fixed carbon species are important in that they are gases undercurrent surface conditions on Mars.

Specifically, gases are readily moved, from source to use site, from well to chemical processing plant. With bothoxidized and reduced species of carbon-bearing gases available on Mars, and with the addition of nuclear- or solar-electric power energy, the synthetic organic chemistry is merely an exercise in chemical engineering. The carbon-bearing source gases are available, and the chemical engineering technology to transform the carbon gases to useful endproducts currently exists. Needed only is the design, deployment and operation of fairly routine chemical processingplants on the Martian surface, factories which will yield a cornucopia of on-site organic matter of crucial value to theMartian colonists.

Consider reaction (1) below, which uses the constituents of methane hydrate as starting materials:

(1) is desirable because it converts reduced carbon (CH4) to oxidized carbon (CO and CO2); oxidized carbon is anecessity for further organic chemical manipulations. However, the enthalpy of the system does not favor the reactiona written. Indeed, the reaction would absorb some 80 kcal of energy to proceed, without proper manipulation. Now,the reaction could be catalyzed, and/or run in a reactor permeable to hydrogen so that the reaction is driven to the right.More than likely, the reaction would be run under high temperature and pressure, requiring power. Alternatively, thewater from methane hydrate could be electrolyzed, again requiring power, as in (2):

the resultant oxygen (O2) could be reacted with the methane from the hydrate, as in (3):

(3) is energetically favorable, IF oxygen is available. The net desirable result of reactions (1) and (3) is to producecarbon monoxide. Keep in mind that carbon dioxide could be available on Mars directly from CO2 hydrate, but it isdesirable to have the chemical technology to convert / utilize the available CH4, even if abundant CO2 were present onMars. Thus, it may be useful, depending on actual feedstock gases, to consider encouraging the following reaction (4):

The net desired result is to obtain CO and H2 as pure as possible, so that the Fischer-Tropsch Process (FTP) can be broughtto bear. The FTP is a reaction of hydrogen with carbon monoxide, generically as follows (5, intentionally unbalanced):

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3CH4 + 3H2O —> 2CO + CO2 + 9H2 (1)

2H2O —> 2H2 + O2 (2)

2CH4 + 3O2 —> 2CO + 4H2O (3)

CH4 + CO2 —> 2CO + 2H2 (4)

carried out with an appropriate catalyst, and under suitable conditions of temperature and pressure. With properselection of these three parameters, the FTP will yield liquid hydrocarbon fuels, oils, waxes, or a variety of other organicchemicals. Catalysis based on cobalt, nickel, ruthenium and iron is widely and effectively employed.

In summary, the presumed abundant methane, carbon dioxide, and water, from hydrates on Mars, can be chemicallyconverted to carbon monoxide (CO) and hydrogen (H2). These gases can be easily converted to higher molecular weightorganic matter using the Fischer-Tropsch Process. Thus, we have a basic process that would yield motor fuels, forexample. Utilization of these on Mars will be discussed later.

For the purposes of colonization of Mars, access to a synthetic structural material, such as a plastic, will be critical. We willconsider the case of synthesizing polystyrene as a structural plastic. The “water-gas” reaction (6) is useful in this context:

Note that hydrogen and carbon monoxide (obtained as outlined earlier) can be reacted in the reverse of (6) to giveelemental carbon. Carbon will react with calcium oxide in an electric furnace to give calcium carbide (7):

and calcium carbide will react with water to give acetylene (8):

and acetylene and be condensed to benzene (9):

which will react with ethylene (from dehydration of ethyl alcohol [10] from the FTP) to give styrene (11). Styrene canbe polymerized to a rigid plastic (12):

These few examples demonstrate the concept of creating useful materials for application on Mars. Beginning with verysimple, essentially inorganic forms of carbon, it is possible to engineer a variety of useful organic-based materials thatcan be fashioned as required to support human habitation of Mars. Please refer to any organic chemistry text book formore detail, and other potential synthetic pathways, on the discussion immediately above.

Energy Sources on MarsThere must be an energy source to support the chemical engineering discussed above and to provide power in general.Synthetic chemistry, even on the restricted industrial scale required by the initial Martian colonies, will require powerfor heating, pressurizing, and irradiating chemical reaction vessels, for example. Dependable high-energy-densitypower sources, at first, can be provided either by a nuclear or solar installation. Once a colonial industrial capability isavailable, distributed power systems (e.g., small combustion engines or fuel cells based on engineered fuels andoxidizers) could become widely utilized.

Although nuclear power is attractive from the standpoint of power density and dependability, the reactor and its nuclearfuel would have to be transported from Earth. However, the reactor need not be brought to the planet’s surface. It couldbe placed in a stable orbit around Mars, or emplaced on either Deimos or Phobos, from where power could be beamed

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H2 + CO —> CH3(CH2)nCH3 + CH3(CH2)nOH + H2O (5)

C + H2O —> H2 + CO (6)

3C + CaO —> CaC2 + (CO + CO2) (7)

CaC2 + H20 —> C2H2 + CaO (8)

3C2H2 —> C6H6 (9)

CH3COH —> C2H4 +H2O (10)

C6H6 + C2H4 —> C2H3C6H5 [Styr] + H2 (11)

n(Styr) —> (Styr)n [polystyrene plastic] (12)

to the surface of Mars via microwave radiation. However, nuclear power has several drawbacks. There are three primeconcerns that must be dealt with. Firstly, is the cost of transporting a relatively heavy reactor from Earth-vicinity toMars. Secondly is the possibility of a nuclear accident in the Earth’s atmosphere or in the vicinity of Mars. Thirdly isthe problem of what to do with the spent nuclear fuel, an issue that has yet to be dealt with satisfactorily on Earth. Ifthe colonization of Mars is operated similar to research activities in Antarctica (a possible precedent), then nuclearpower may be prohibited on the planet.

If concerns about nuclear power are overwhelming, solar energy is likely to be the initial power source for a Martiancolony. A key factor in this energy equation is the fact that Mars is roughly twice as far from the sun as is Earth, andthus receives roughly one-quarter the energy per unit area as does Earth. Solar collectors on Mars would thus need tobe some four times as large as they would need to be on Earth for the same energy output. This situation may at firstappear to be a significant and costly transportation problem if one were contemplating bringing bulky and heavy solarpanels to Mars. New technology lightweight panels may solve the weight concern, but not necessary the bulk problemsof transport. However, an alternative approach would be to use light-weight plastic-film-based solar radiation collectorsto boil water to give high pressure steam fed to electrical generators.

If abundant methane hydrate occurs in suitable proximity to the planet’s surface, then synthetic FTP fuels can bemanufactured. These fuels could be used to drive conventional turbine or reciprocating engines. Stirling (externalcombustion) engines, however, may provide an optimal solution for Mars because they operate under very low stress,and could be constructed from indigenous materials (e.g., plastic and ceramic materials), as opposed to internalcombustion engines that require high-technology metallurgy (assuming the availability of metallic ores). On the otherhand, hydrogen stripped from the methane may be used in fuel cells to provide electricity.

DiscussionHere, then, is an emerging challenge for the chemical industry. In order for successful colonization of Mars to occur,potential colonies should be self-sustaining there as soon as possible. Instead of transporting all the items needed forhuman habitation of Mars, standard industrial chemical plant must be designed to be carried to Mars and optimized foroperation on Mars itself. This apparatus would have to be relatively small and energy-efficient, as well as being able tomanufacture a variety of plastics and objects, some of them complex in form. Development of this capability, involvingdevelopment of nanotechnology, MEMS, and other new processes is now possible. The chemical industry shouldbecome part of the planning and development process for space research, human space travel, and extraterrestrialcolonization ventures. Indeed, there has recently been reported a quantum leap in this direction. The Virtual EngineeredComposites (VEC) process is discussed at length in a recent TIME magazine article. The VEC is likened to a “3-D faxmachine” in which moldable plastics are formed on-site using new technology controlled from a remote location via anelectronic link. In essence, the design goes in one end of the electronic line, and a finished product pops out of thefabrication unit on the other end! One needs only supply semi-finished plastics (as discussed above) to the fabricationunit; software and the VEC unit do the rest (Gibney, 2000).

Fuel is vital for both energy and byproduct production on the Martian surface and for fueling the return trip to Earth. Ifenergy-dense fuel can be produced on Mars, then Mars will be a true stepping stone to exploration of the entire SolarSystem. Artificially produced FTP has been shown to be motor fuels. These hydrocarbon fuels, or hydrogen, whichwould have to be liquefied for use in a rocket vehicle, could be combusted using gaseous oxygen, from the electrolysisof water, as the oxidizer. The benefit of FTP-liquids over hydrogen is that they are naturally liquid under a wide rangeof pressure-temperature conditions and does not need special cryogenic handling or storage facilities, as does hydrogen.

In this paper, discussion of organic chemical engineering has been confined to producing useful organic compoundscontaining only carbon, hydrogen, and oxygen. There are myriad other organic materials which incorporate such atomsas chlorine, sulfur, phosphorus or nitrogen, for instance, which would allow for very sophisticated materials to bemanufactured. Martian colonists may wish to engineer polyvinyl chloride (PVC) as a structural material. For PVC, thecolonists would need a source of chlorine, which is easily produced by the electrolysis of salt (NaCl). Are there salt

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deposits on Mars? If there was standing water on Mars there may well be salt deposits related to ocean evaporation.Such deposits could also contain nitrate (e.g., NaNO3) or phosphate (e.g., K3PO4), which would provide readily usableindustrial feedstock. And, of course, both nitrate and phosphate are required as fertilizer for any attempts to grow plantbiomass on Mars.

In the longer term, use of methane as a fuel and in other chemical processes will produce CO2 gas. This will increaseatmospheric CO2 and will aid the greenhouse effect over time even without a planned atmospheric remediation plan,although initially there will be little impact. Increasing atmospheric density and enhancing the greenhouse effect of theatmosphere should render Mars more amenable to habitation in the longer term. Both methane and carbon dioxide arestrong greenhouse gases, and if released in sufficient quantities, could lead to marked warming on the planet. Of course,it is highly probable that enough CO2 and other greenhouse gases would be released into enclosed space (e.g., largegreenhouses) to allow the cultivation of biomass on Mars without remediating the atmosphere as a whole, at leastinitially. If the correct woody plants were to be cultivated, colonists would have access to wood, a superb engineeringmaterial. Further, the wood would probably be cultivated from essentially sterile cuttings or seeds, so that theimportation of serious plant diseases, rot fungus, or termites, which would compromise the wood, could be precluded.Whereas it seems potentially useful to produce synthetic carbon-based chemicals and materials for short term objectives,biomass would supply a cellulose-based byproduct for the long-term. If methane hydrate concentrations can be locatedon Mars, their location may provide the determining factor in selecting habitation and colonization sites there becausethey will contain the basic elements necessary for human habitation: water, power, food, shelter. In addition, any locallyderived materials used in the inhabited installations will not accrue the transport costs of bringing such materials fromEarth. For true colonization to be contemplated, the inhabitants of Mars must be as self-sustaining as possible.

Mars beckons constantly. Since even before ancient astronomers noted a “red wanderer” among the fixed stars, Marshas beckoned. As a race, we have always been called to the planet, at first only visually, but now as a defining challenge.Now, it is time, and increasingly possible, to seize the elevating opportunity offered by the Red Planet. Technology inhand will permit us to travel to Mars, to establish beachheads, to prevail. The authors have given a brief sketch of someavailable technology, to be applied to Martian natural resources, which will undergird colonial success after thepioneering explorers and soon-to-follow colonists create footprints, and more, on Mars. Needed only is the will to fulfillour interplanetary destiny.

References1. Dillon, W.P., Danforth, W.W., Huthchinson, D.R., Drury, R.M., Taylor, M.H. & Booth, J.S. 1998. In: Henrtiet, J.-P., & Mienert, J., (eds). Gas

Hydrates: Relevance to World Margin Stability and Climate Change. Geological Society London Special Publication 137, 293-302.2. Gibney, F., Jr. 2000. The Revolution in a Box. TIME Magazine, V. 156 #5, 55 - 61.3. Max, M.D. (ed). Natural Gas Hydrate: In Oceanic and Permafrost Environments. Kluwer Academic Publishers, London, Boston, Dordrecht,

414pp. (in press).4. Max, M.D. & Chandra, K. 1998. The dynamic oceanic hydrate system: Production constraints and strategies. OTC 8684. In: Proceedings of

the Offshore Technology Conference, 4-7 May 1998, Houston Texas, 217-226.5. Max, M.D. & Dillon, W.P. 1999. Oceanic methane hydrate: The character of the Blake Ridge hydrate stability zone and the potential for

methane extraction: Author’s correction. Journal of Petroleum Geology, 22, 227-228.6. Max, M.D. & Clifford, S. 2000. The state, potential distribution, and biological implications of methane in the Martian crust. Journal of

Geophysical Research-Planets, 105/E2, 4165-4171.7. Max, M.D. & Clifford, S.M. Initiation of Martian outflow channels: Related to the Dissociation of Gas Hydrate. Geophysical Research Letters

(in press).8. Max, M.D. & Lowrie, A. 1996. Methane hydrate: A frontier for exploration of new gas resources. Journal of Petroleum Geology, 19, 41-56.9. Sloan, E.D., Jr. 1997. Clathrate Hydrates of Natural Gases. Marcel Dekker, Inc., New York and Basel, 730pp.

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Terraforming Mars And Greenhouse Gases

M. M. Marinova; C. P. McKay[2001]

IntroductionImagine walking through a forest of tall trees, with a blue sky and white clouds overhead, and one-third gravity. Thisis the concept behind terraforming Mars: to bring to life a planet that is now cold, dry, and very inhospitable to livingorganisms. The process of terraforming a planet can mostly be described as the warming of the surface and thethickening of the atmosphere so that liquid water can persist on the surface. Beyond these requirements, the desiredsurface temperature and composition of the atmosphere are determined by the types of organisms which are to live there.Terraforming commonly refers to creating a “second Earth” – creating conditions allowing both plants and animals tosurvive. An important step in the process of terraforming is ecopoiesis, where the planet is just clement enough to allowonly some types of life to survive. For example, Mars would be suitable for microorganisms and plants if it was warmand wet, even if its atmospheric composition remained mostly carbon dioxide, and was not capable of supporting higher-order Earth animal life.

The initial warming of Mars (ecopoiesis) is likely to take on the order of a hundred years. Trees and grasses on Marswould produce oxygen that might naturally make a breathable oxygen-rich atmosphere, but simple energyconsiderations show that this would take on the order of a hundred thousand years (McKay et al., 1991; McKay andMarinova, 2001).

Numerous reasons have been used to support the terraformation of Mars. The reasons can be grouped into three broadcategories: (1) terraforming for scientific and practical knowledge about how planetary scale biospheres work; (2)terraforming as part of the human expansion beyond Earth; and (3) terraforming as a way to spread life – the gift fromEarth to the rest of the Solar System. Terraforming Mars will be spurred by all of these motivations, and newmotivations that we cannot glimpse but will become important in the future.

We can learn about how a habitable planet works by considering how to reconstruct one. The terraforming of Mars iscertain to teach us about the warming processes that are currently taking place on the Earth. While there is still muchcontroversy about why the Earth is warming up, it is certain that at least some part is due to human activities such asthe release of more carbon dioxide and other super greenhouse gases (e.g., CFCs) into the atmosphere. Perhaps bywarming Mars we will learn how to start the reversal of such warming, and overall how to take better care of our planet.However, scientific curiosity is generally considered an insufficient reason by itself for carrying out such a large projectas terraforming, which is very demanding technologically, economically, and ethically.

As humans advance scientifically and technologically, we are bound to step out towards other worlds. Mars is the nextlogical step, and terraforming the planet may be a natural part of that expansion. Terraforming Mars will certainly givehumans and life from Earth a second home, and will make Mars more accessible to the broader public. A newlyterraformed Mars may be the place that forward-looking people go to in search of a new start in a new land. Indeed,the human need for frontiers and the importance of expansion in invigorating human culture is often cited as a keymotivation for making Mars a new home for life.

A third, new, but profound reason for terraforming Mars is to spread life beyond the Earth. Looking out into the Universe,we see many curious and interesting phenomena. But the phenomenon that is the most interesting from a scientific andhuman-value perspective is life: life right here on Earth; the assortment of plants and animals that we take for grantedevery day. While present in various forms, all life on Earth shares the very same origin. And when we look out into theUniverse we have as of yet not found any signs of extraterrestrial life. In terraforming Mars, we will be spreading life toanother planet, increasing the diversity of life we currently see, and watching the evolution of a new biosphere, as life

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M. M. Marinova; Massachusetts Institute of Technology and NASA Ames Research Center, [email protected]. P. McKay; NASA Ames Research Center, [email protected]

adapts to its environment, and as life changes its environment. The terraforming of Mars is not incompatible with thesearch for life on Mars, and with the finding of life on Mars. Mars is believed to have had very much the same initialconditions as those on the Earth. Therefore, if life developed on Mars, it would have been under conditions similar tothose on early Earth, that is on a warm planet with a thick CO2 atmosphere and with liquid water present on the surface.The initial terraforming of Mars will recreate just such a place. If there are Martian organisms in the subsurface ordormant in the permafrost they would be able to expand and flourish in this recreated Martian biosphere.

It is important to dispel one impractical reason sometime given for terraforming Mars. This is making Mars habitableas a way to solve the overpopulation problem on Earth. For better or worse, Mars is not a solution to these Earthlyconcerns. Even advanced technology would not be capable of sending people to Mars at a rate even close to the rate ofpopulation growth, much less moving the entire population in the event of ecological collapse on Earth. It is alsounpractical, and we think unethical, to think of Mars as a back-up in case we make the Earth uninhabitable, and to usethat as a justification for polluting the Earth.

Magic versus Current Technology in Terraforming MarsNumerous papers have discussed various methods for terraforming Mars (Figure 1). Some of these methods fall withinthe bounds of current technology, while others are much further into the future. Unfortunately, proposals based onfuturistic technology outnumber those based on current or foreseeable technology. One proposal calls for the placingof giant mirrors in orbit around Mars, thereby increasing the average solar insulation. One reason why Mars cooledmuch more drastically than the Earth, since the forming of the Solar System, is that it is further from the Sun than theEarth and therefore receives 2.3 times less solar energy, causing it to be cooler. By increasing the average amount ofenergy hitting the surface of the planet, the surface temperature will increase. However, the making of large mirrors inspace is currently beyond our technological capability, and in order to increase the solar insulation by even 2%(equivalent to a temperature increase of about 1ºC (2ºF)) would require a mirror the size of Texas (McKay, 1999).

The temperature resulting from a certain solar insulation depends on the albedo of the planet (how dark the planet is andtherefore how much of the incident energy is absorbed). The polar caps, covering a significant portion of the planet (~1%; Kieffer et al., 1992) have a very high albedo, thereby reflecting a substantial fraction of solar energy rather thanabsorbing it. It has been proposed (Fogg, 1992) to sprinkle dark dust over the poles, thereby decreasing their albedoand warming them. This will serve a two-fold purpose of both warming the planet directly, but perhaps moreimportantly the warming will cause the targeted release of carbon dioxide and water, which will significantly help infurther warming Mars. While this method seems rather attractive, it has as drawbacks the difficulty of aerial platforms(as dust sprinklers) due to Mars’ thin atmosphere, as well as the sinking of the warmed dust into the ice which wouldlead to the need for frequent dust replenishing.

A method to increase both the volatile inventory of Mars, and also warm up the planet is through the impacting of icy(comet) objects into Mars. This type of impact will most notably cause a local increase in temperature, creating a smalloasis. This method is again out of our reach since we do not have the capability of moving, much less accurately aiming,very large objects through large distances. Furthermore, the impact may impact erode more volatiles than are imported,if the impact velocity is not sufficiently small (Fogg, 1992). As well, the lack of precision in targeting the impact sitemay be unsettling to the Martian settlers.

The most viable technique for warming Mars, so far, appears to be the use of super greenhouse gases. The technologyhas been proven – it is currently being demonstrated on the Earth. Since the gases can be manufactured on Mars anddo not need to be brought from the Earth, it is a viable near-term method.

The Inside Workings of Super Greenhouse GasesThe most commonly known greenhouse gases are carbon dioxide, water vapor, ammonia vapor, and CFCs(chloroflourocarbons). Of these, CO2 and H2O vapor are responsible for keeping the Earth at a comfortable averagetemperature of 15ºC (59ºF), which is ~30ºC (54ºF) above what it would be otherwise. While greenhouse gases on the

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Earth are crucial in keeping the Earth habitable, too many greenhouse gases (in conjunction with a close proximity to astar) can also render a planet uninhabitable, as exemplified by Venus. Super greenhouse gases derive their name frombeing more efficient than the more common greenhouse gases; in particular compared to CO2.

Greenhouse gases are transparent to visible light. Sunlight passes virtually unobstructed through the atmosphere, andis absorbed by the ground, which is then warmed up. The warm ground radiates out in the infrared (IR) spectrum.Greenhouse gases are very effective at absorbing light in the IR, thus they block it form escaping into space and insteadwarm the atmosphere, which in turn warms the ground. Greenhouse gases can be thought of as a blanket around theplanet; the thicker the blanket the warmer the surface.

The effectiveness of a greenhouse gas is dependent both on what fraction of the IR energy it absorbs for a certain gasamount at a specified wavelength, and by where the absorption bands are placed in the IR spectrum. Every objectradiates at various wavelengths depending on its temperature (Figure 2). The placement of the absorption bands iscrucial – if they are placed at where the body radiates most of its energy then that gas will have a very strong warmingeffect. If the bands are placed on the outskirts of the blackbody curve, the gas will not be as effective. Super greenhousegases have been very efficient partly because their absorption bands fall in the “window region” – the area between 8 -12 µm (1250 - 830 cm-1) where CO2 and H2O vapor are not effective absorbers and the thermal radiation is still strong.

Since different gases absorb at different wavelengths (Figure 3), if only one greenhouse gas is used, large transmissionholes become apparent in the IR spectrum and the planet is not warmed efficiently. Furthermore, the warming due to aparticular gas increases with diminishing return with the amount of gas. Therefore, in order to warm a planet efficiently,a cocktail of various carefully chosen super greenhouse gases should be used, keeping all the gases at lowconcentrations. Going back to the blanket analogy, this is a very similar effect to that of wearing many layers, ratherthan one very thick layer – that is using small amounts of many different gases rather than a large amount of one gas.

Super greenhouse gases have earned a bad reputation on the Earth, where the increase in temperature is undesirable. Themost common artificial super greenhouse gases on the Earth are CFCs, which are also very effective at destroying the ozonelayer, further harming the environment on the Earth. However, on Mars the increase in temperature will be desirable! Inaddition, if PFCs (perfluorocarbons, very similar to CFCs but do not contain chlorine or bromine) are used, then the ozonelayer will not be harmed. PFCs have no harmful effects to living organisms, especially at low concentrations.

Criteria for Greenhouse GasesWhen deciding on greenhouse gases to be used in terraforming Mars, factors such as efficiency, easiness ofmanufacturing, long lifetime against destruction by solar UV light, presence of all necessary elements on Mars, noharmful effects to life, and ability to be incorporated into biological cycles must be considered.

The efficiency of a greenhouse gas is measured by the increase in temperature for a given amount of gas produced. Thehigher the increase in temperature, the more desirable the gas. As stronger greenhouse gases are discovered, theterraforming of Mars becomes increasingly more viable since the energy requirements for the process decrease with thedecrease in the amount of gas that needs to be manufactured.

It is not practical for greenhouse gases to be carried to Mars from the Earth. Even though super greenhouse gases areto represent only a very small fraction of the atmosphere (about 0.1 to 1 part per million), this is still a very significantmass to be carried across space. Therefore, the gases will need to be manufactured on Mars. This should not beexceedingly difficult since the gases are commonly made on the Earth, and similar processes are likely to be applicableto Mars. In order to manufacture the gases on Mars, all the required elements must be available in significant quantitiesin the soil or atmosphere.

Since the goal of terraforming Mars is to make the planet more habitable to life, using gases that have negative effectson life would be counter-productive. Most super greenhouse gases are not toxic. However, gases that contain chlorine

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or bromine, such as CFCs, are very destructive to the stratospheric ozone layer, and therefore are harmful to life. Idealgases would not contain chlorine and bromine and would be inert in the atmosphere. Candidates include PFCs(perfluorocarbons; which are made up only of carbon and fluorine) and some sulfur containing compounds such as SF6.

An ideal situation in the terraforming of Mars would be to make the emerging biosphere capable of keeping its ownenvironment warm and comfortable. In terms of the use of super greenhouse gases, this translates into bioengineeringmicroorganisms which themselves produce the super greenhouse gases until the temperature reaches a certain threshold.Organisms have been found which do produce halogenated compounds (Tokarczyk and Moore, 1994; van Pee, 1996;Wackett, et al., 1994); it is likely within the near-term capability of biotechnology to transform the organisms so thatthey stop producing the greenhouse gases when a certain temperature is reached. Thus, it is desirable to use supergreenhouse gases, which can be incorporated into biological cycles.

Putting together all the requirements for super greenhouse gases and the resources that could be reasonably devoted toterraforming Mars, the project remains a practical possibility. Several super greenhouse gases satisfy all of the aboverequirements. Furthermore, because of their strong greenhouse potential, these gases need to be manufactured to lowconcentrations in order to produce a very strong greenhouse effect. Because of their long lifetimes, several thousandyears (Fogg, 1995), the rate of production remains reasonable. Still, it must be realized that the energy requirements formanufacturing the gases are not trivial. On the order of 4x1020 Jules, equivalent to about 75 minutes of Martiansunlight, will be required to produce enough PFCs to raise the temperature of Mars by about 5ºC (9ºF) (McKay andMarinova, 2001). This is equivalent to 250 facilities consuming 500 MW (the size of a small nuclear reactor) workingfor 100 years. While these energy requirements are large, they are certainly not unachievable. In addition, the predictedtemperature increase is likely low since it does not take into consideration various feedback effects, as well asoptimizing the mixture of greenhouse gases.

Analyzing the Greenhouse Potential of Super Greenhouse GasesThe greenhouse potential of gases can, at first look, be compared by their transmission spectra; the more absorptionbands that the gas has (the less energy it transmits), the more efficient it will be. The placing of the bands is alsoimportant, specifically covering the 8 - 12 µm (1250 - 830 cm-1) region. Figure 3 (a) and (b) compare the transmissionspectra of CO2 and C3F8 for the same concentration of gas.

In order to be able to use the transmission data in numerical analysis, the change of transmission with increasing gasconcentration should be described by an exponential sum fit. Figure 4 shows the transmission for a strong C3F8absorption band, fitted using a 3-term exponential fit.

Once the exponential term fits are obtained, they are incorporated into a model calculating the downward flux generatedby the presence of a gas amount in the atmosphere, as described in Marinova et al., 2000. The results of this analysisfor current Mars are shown in Table 1; only gases which are good candidates for terraforming Mars are shown. Whilethe results look very promising, it is important to note that the real-life warming will likely be somewhat higher.

As the planet warms up, CO2 will be released from the melting polar caps and from the regolith. Once the planet warmsup above about 0°C, water vapor too will become an important part of the atmospheric gases. With time, CO2 and watervapor will become the dominant greenhouse gases, with artificially or biologically produced super greenhouse gasesproviding a warming effect primarily in the window region. In present models, the source of CO2 is regolith outgassingor melting of the polar caps (McKay et al., 1991; Zubrin and McKay, 1994; Fogg, 1995).

The temperature increases shown in Table 1 corresponds to individual gases. Using only one gas is not efficient sincethe warming effect is not linearly related to gas amount; the absorption bands become saturated and are no longereffective. In order to plug up all parts of the spectrum and avoid the saturation of bands, a carefully chosen mixture ofgases should be used. Currently the model does not calculate the warming due to a mixture of gases.

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Current work is focused on making a radiative-convective model of the Martian atmosphere, thereby providing a moreaccurate calculation of the warming due to greenhouse gases. Taking into account the CO2 released from the polar capsand the regolith as the planet warms will add another dimension of realism to the calculations.

Using a Synergetic ApproachResults from the analysis of greenhouse gases have shown that they are a viable method for the warming andterraforming of Mars. However, the energy requirements are not trivial. Like the nonlinear warming due to greenhousegases discussed above, other methods for warming the planet are also more effective when conducted in a limited, buttargeted, manner. Therefore, the use of a synergetic approach to terraforming is likely to be the most effective andefficient (Fogg, 1992). Super greenhouse gases are likely to lead such an effort, but the use of various other techniquesshould not be underestimated.

The Ethics of Terraforming MarsNo discussion of terraforming Mars would be complete without consideration of the ethical and social questions raised.Foremost of these is the question of indigenous life. If Mars had an early Earth-like epoch then it is likely that life aroseduring this early period and it is possible that there are still subsurface ecosystems or frozen dormant organisms in theancient permafrost. The ethical issues are reduced or even eliminated if the Martian life is the same as Earth life,indicating that both planets share a common biological history – the Martians are our cousins. However, if Martian lifedoes indeed represent a second genesis of life, then the ethical issues are profound. There are three possible approachesto dealing with alien Martian life. First, we could capture a sample for scientific study and preservation and proceed tointroduce life from Earth. Second, we could decide to leave it alone – neither helping nor hurting it. Third, we couldstudy the life and alter the Martian environment so as to allow that life to create a global biosphere – a Mars full ofMartians. These three approaches touch on deep ethical questions. We suggest that the best approach is the third one,which maximizes the richness and diversity of life in the solar system (McKay, 1990; 2001); this approach is consistentwith the terraforming of Mars. If there is no viable life on Mars, it is probable that if there was ever life on Mars itsgenetic information is still preserved in the frozen ground. Even if over time this Martian genome has becomefragmented and non-viable, with future biotechnology it may be possible to reconstruct it from the pieces. Thus, humansmight play a role not just in restoring the Martian environment but also restoring the Martian genome.

If there was never life on Mars then the ethical issue deals simply with the choice between a rich, beautiful, scientificallyinteresting world devoid of life and a rich, beautiful, scientifically interesting world full of life. To us the choice is clear: life.

ConclusionPlanets that are good for life are hard to find. In our solar system we have only our Earth. However, Mars appears tobe a world that could be made a friend for life using the unique capabilities of human technology and the powerful forcesof evolutionary biology. Our present knowledge of Mars is not sufficient to be certain that we can terraform Mars or toshow the final path to terraforming. However, the data collected so far and the studies done to date indicate that alteringMars to allow for a plant-based biosphere is a possibility, and one that could begin in our generation and be completedin the life-times of our great-grandchildren.

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Figures

Figure 1. Several of the methods proposed for warming Mars and re-creating habitable conditions on that planet.Of the methods shown, greenhouse warming is the one approach that has already been demonstrated on Earth.

Figure 2. Thermal radiation (black body curves) from the surface of Mars and Earth corresponding to temperatures of -60°Cand +15°C, respectively. Also shown are the main spectral regions for the absorption of thermal radiation by atmosphericwater vapor, carbon dioxide, and super greenhouse gases. Super greenhouse gases can absorb in the “window” region

where neither water vapor nor carbon dioxide absorb.

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Figure 3. Transmission spectra for (a) CO2 and (b) C3F8, at a concentration of 10% in Argon (Ptot=101.3kPa).

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Figure 4. Exponential sum fit for a C3F8 strong band: 700-752 cm-1.The values in the fit are: a1=0.456, k1=2.43 x 10-23 m2 molecule-1, a2=0.342, k2=3.31 x 10-25 m2 molecule-1,

a3=0.2, k3=1.27 x 10-24 m2 molecule-1; C is the column concentration of the gas in units of molecules m-2.A three term exponential sum is a convenient way of expressing the transmission in a band as a function

of increasing concentration of the gas molecules that contribute to the band.

Table 1. Warming of Mars due to greenhouse gases. Only gases suitable for terraforming Mars (no Cl or Br) are shown(atmosphere on Earth = 101,300 Pa).

Table 1. Temperature increase from greenhouse gases on Mars.

References1. Fogg, Martyn J., 1992. A Synergic Approach to Terraforming Mars. J. Brit. Interplanet. Soc 45, 315-329.2. Fogg, M. J., 1995a. Terraforming: Engineering Planetary Environments. SAE, Warrendale, PA.3. Marinova, M.M., C.P. McKay and H. Hashimoto, 2000. Warming Mars using artificial super-greenhouse gases. J. Brit. Interplanet. Soc. 53, 235-240.4. Kieffer, H.H., Jakosky , B.M., Snyder, C.W., and Matthews, M.S., 1992. Mars. University of Arizona Press, Tucson.5. McKay, C.P., 1990. Does Mars have rights? An approach to the environmental ethics of planetary engineering. In Moral Expertise (D.

MacNiven, Ed.), pp. 184-197. Routledge, London and New York.6. McKay, C.P., 1999. Bringing Life to Mars. Scientific American Presents, 10, spring, no. 1, 52-57.7. McKay, C.P., 2001. Martian Rights: Prioritizing Martian Life Over Human Settlement, The Planetary Report, in press.8. McKay, C.P. and M.M. Marinova, 2001. The physics, biology, and environmental ethics of making Mars habitable, Astrobiology, 1, 89-109.9. McKay, C.P., O.B. Toon, and J.F. Kasting, 1991. Making Mars Habitable. Nature 352, 489-496.

10. Zubrin, R.M. and C.P. McKay, 1997. Technological requirements for terraforming Mars. J. British Interplanet. Soc. 50, 83-92.11. Tokarczyk, R., and R.M. Moore, 1994. Production of volatile organohalogens by phytoplanktonic cultures. Geophys. Res. Lett. 21, 285-288.12. van Pee, K.-H., 1996. Biosynthesis of halogenated metabolites by bacteria. Ann. Rev. Microbiol. 50, 375- 399.13. Wackett, L.P., M.J. Sadowsky, L.M. Newman, H.-G. Hur, and L. Shuying, 1994. Metabolism of polyhalogenated compounds by a genetically

engineered bacterium. Nature 368, 627-629.

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“Thinking Long Term” – Investing Today for a Mars Future Tomorrow

Thomas Andrew Olson[2000]

AbstractIn 1944, a New York woman invested $5000 – one time – in a stock portfolio. At the time of her death 51 years later,her estate, based on that growth of that single managed investment, was worth $22 million. A $4000 investment inCoca-Cola in 1919, just after it’s reorganization, would today be worth over $600 million. These are not “fluke” data.Despite a major depression, a world war, 3 other major conflicts, a Cold War, and several recessions, the US stockmarket gained an average of 10.4% per year over the entire 20th Century.

It is the nature of governments to spend wastefully, rather than truly invest for the future. All government bureaucracies,NASA included, are forced by the D.C. budget process to spend their allotted budget, in order to maintain fundingcommitments the following fiscal year, in a “use it or lose it” policy. Could such “waste” be measured, and had it beenconsistently invested in growth equity markets over the last 30 years, NASA could be almost self-sustaining today!

Despite a record-breaking period of economic growth, the author will show figures to prove why the cost of thecolonization of Mars will never be borne by the U.S. government alone, heralding the call for global partnering, and asquick a move as possible to private sector entrepreneurial firms and investments.

The author will show common-sense methods by which small investments made now, by increasingly larger groups ofpeople, can yield vast rewards for future generations – such as seed funding for a Martian colony. The key, as in anyworthwhile endeavor, is patience and perseverance.

Part One: Colonization – Can the U.S. Government “Go It Alone”?One of the prime missions of the Mars Society is to help mobilize public support for missions to the Red Planet. Thisis a laudable goal and should, of course, be pursued. But this pursuit should also include a clear picture of all theobstacles we face in taking that road, and the history behind them. This paper will attempt to provide that picture here,and offer a compelling supplement – if not an outright alternative – to that strategy.

If our shared goal was merely exploration of Mars, NASA – having first been blessed and budgeted by Congress – as itinitiates nothing without Congressional approval – could no doubt achieve that goal by 2012-2014. But our purpose isMars settlement – a functioning series of self-sustaining colonies, as a spearhead for the next phase in the evolution ofhuman civilization. Settlements cost a lot more than exploration missions, and no one government could foot that billalone – not even the US, by far the wealthiest and most powerful nation on Earth today.

“What,” you say? “The US economy is larger than at any time in history, boasting an astounding 9 Trillion dollar GrossDomestic Product for 2000. If we only shifted a few national priorities, we could afford it easily!”

I can silence that argument with one word – one I will employ later. For now, though, let’s look at some more history:

Although I have data from the Archives going back as far as 1934, I have chosen to concentrate on the last 30 years onlyfor purposes of presentation.

The first line in the chart I wish to address tracks total US tax receipts as a percentage of GDP. As you will notice, thatline is relatively flat, only varying between 17.5%-20.6% over the last 3 decades. This is actually rather an interestingdiscovery – regardless of the growth of government taxation and spending (and people’s complaints about it), the growthof tax receipts is not in any real way disproportionate with the US economy as a whole. It was 20% as far back as the

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Thomas Andrew Olson; CEO, The Colony Fund LLC, New York, NY, USA; E-mail: [email protected]; web: www.colonyfund.com

height of World War II in 1943, and hit its only low point of 14.4% in 1953. Other than that exception, the line for thelast 50+ years is pretty much as you see here, relatively flat.

Source: Office of Management and Budget

Now let’s add the next line:

Source: NASA

The second line in the chart depicts the NASA budget, as a percentage of the Federal budget as a whole over the last 30years. Here, also, that line is relatively flat, varying between a 1970 high, at the height of the Apollo program, of 1.9%,to an all-time low of 0.7% in 1986, in the wake of the Challenger disaster. This averages out to be 1.02% of US

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expenditures annually. Since that flat line runs relatively parallel to that of total tax collection relative to GDP, it can besaid that NASA’s budget has grown at an almost linear pace with that of government as a whole. Many would claimwe are getting a lot of bang for that buck, considering. But we’re far from finished…Now let’s add Defense spending:

Sources: Office of Management and Budget, General Accounting Office, NASA

Hey, looking better, isn’t it?

The green line in the chart shows the Defense budget, also as a percentage of the Federal budget, over the last 30 years.Here, we have a definite downward trend. Remember the “peace dividend” we were supposed to get from the end ofthe Cold War? This line would suggest that’s finally happening. Of course, remember that it’s only the percentage ofmilitary spending out of the budget as a whole that has dropped. Keep in mind that when you think about the red line,government budgets have grown at a tremendous rate, right along with the economy, and federal outlays today are 9times what they were in 1970! If you are the Secretary of Defense, which would you rather have, 41% of $280 billion,or 16% of $2.5 Trillion?

Even so, with all that huge economy and drop in real defense spending, federal funding of Mars colonization should bea snap, right? Not so fast…remember, spending in real dollars grew from 280 Billion to 2.5 Trillion in the last 30 years.So, if taxation has remained constant, NASA spending has remained constant, and Defense spending has dropped, whereis all the money going? Therein lies the rub…and the “one word” that could shoot down all our government-fundedMars dreams:

“Entitlements” . . .

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Source: IBID

Here is the Great Budget Killer that everyone in D.C. is too politically correct to talk about, the overwhelming burdenon the body politic. I gave the line a gold color and a thicker weight for that reason. Entitlements, or “direct paymentsto individuals” (by GAO definition), is indeed, for 10’s of millions of Americans, the “golden goose.”

Entitlement spending was only 27% when John F. Kennedy committed us to the race to the Moon. It had only grownto 33% by 1970. But with Vietnam winding down, and interest in lunar adventures waning, the social pressure was onto increase funding for all the Great Society programs initiated by Lyndon Johnson. The tap continues to increase it’sflow, projected to reach the 67% mark by 2005 – think about it – by 2005, a full 2/3 of the taxes you pay goes directlyinto someone else’s pocket, with government being the great middleman. If that goes on, the government of the US willbe totally bankrupt by 2030 – unless, of course, that 50-year, 1-to-5-ratio history of taxation-to-GDP, that “hiddencovenant” with the American people is dramatically altered. That could cause the economy the tax-base depends uponto spiral down dangerously, thus killing the proverbial Golden Goose.

That huge number of entitlement recipients also amounts, today, to a large and powerful lobby and voting bloc. At therisk of being labeled cynical, I must conclude that Congress would shut down NASA completely before allowing thatvoting bloc to lose its meal ticket. The dream of Mars will die with it.

Part Two: Is Nasa Worthy?Even is we could somehow craft a salable Mars-settlement strategy to the US Congress, is the only space agency wehave – NASA – capable of carrying the ball?

Again, let’s look at some figures:

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Here is the history of NASA’s budget, in adjusted-1999 dollars, from 1970 to the present.

In that time we have seen the end of Apollo, then Skylab, Pioneer, Viking and Voyager, the Shuttle, the Hubble,Pathfinder, and now the ISS. Since Apollo, all manned space activities have been limited to low Earth orbit. Are wegetting bang for our space buck? Again, in inflation-adjusted dollars, NASA has spent over the last 3 decades over $409Billion. In “reverse inflation,” that’s $88 Billion Apollo-era dollars – or, the equivalent of spending 3 2/3 total Apolloprogram budgets! For that kind of spending, we should have stood on Mars at least once, in all that time. $409 Billionspent over the last 30 years should have definitely given us more than we currently enjoy as a society, not to mentionthe fact that private space ventures should have been encouraged, rather than stonewalled, by the Agency.

Where does NASA’s money go? A significant chunk, nearly half, goes to the costs of expensive and sophisticatedmachinery for the Shuttle missions. According to NASA Chief Dan Goldin, $5 Billion/year is spent on launch alone.The shuttle itself has been criticized for years as being too complicated and expensive to maintain, and has kept the costof space flight at $10,000/pound, which was exactly the same amount we were paying, in constant dollars, during Apollo.

Part 3: The Power of the MarketIn 1995, Ms Anne Schreiber of New York City passed away quietly. She had a long, full, but rather unremarkable life.Like most people, she left behind an inheritance. In fact, the only reason we ever heard of her was that she deeded herentire estate to New York’s Yeshiva University. Ms. Schreiber’s personal net worth at the time of her death wasapproximately $22 Million. A little research uncovered that 50 years earlier, Ms. Schreiber had taken $5000meticulously saved, and invested it in the US equity markets. She, along with the assistance of her broker, hadconservatively and conscientiously traded and managed that single, one-time investment, through 4 wars, 3 recessions,and decades of political upheaval and change, to reach that 1994 valuation.

Immediately after World War I, the Coca-Cola Company was considered all but dead. It’s product, a green colored,uncarbonated, cocaine-laden concoction, having been packaged as a health elixir since the 1880’s, had lost its appeal inthe marketplace, in the light of tastier competition. On the verge of bankruptcy, they had two options: change or perish.

So they changed. Almost overnight their product evolved from the “substance” described above to the product we knowtoday, and their marketing plan refocused itself towards the product merely being a tasty, refreshing mass-market thirst

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quencher. They reorganized the company, and floated a new stock offering in 1919 to raise the initial capital for theproduct relaunch.

Had your grandfather or great-grandfather made a $4000 investment in that stock offer in 1919, your inheritance wouldtoday be worth an astounding $622 Million!

These examples are by no means “flukes.” There are millions of unsung stories out there, told by hundreds of companiesand millions of individual investors over the last 80 years, concerning the power of equity markets in the US, and howinvesting long-term yields incredible benefits for those who are willing to think long-term and stay the course.

The chart on the next page indicates why. While over a short term (like this year) the market may appear to fluctuatedramatically and cause short-term investors fits, the long term is a very different story. In 1972, the Dow broke 1000for the first time. 29 years later, it’s averaging around 11,000. The point is, that despite short-term problems, the generaltrend of the markets is – always – upward. In the 20th Century, the Dow rose an average of 10.4% annually – despitedepression, recessions, wars, and significant sociopolitical change. Unless western civilization collapses entirely, andwith it, the rest of the global economy, there is no compelling reason to believe that this trend will not only continue,but also even improve during the 21st century – particularly if we can manage to stay out of the aforementioned globalwars and depressions.

Okay. We’ve established that markets are good things, and relatively safe places to invest for long-term growth. Now,what does this have to do with Mars?

In any major human endeavor, fiscal commitments must be made long term. Governments have shown that, given thepolitical will, large-scale projects can be successfully achieved, from the Suez Canal, to Hoover Dam, the invasion ofNormandy, the Manhattan Project, and Apollo. Most of these projects were crash programs, with little or no budgetaryconstraints, Herculean tasks performed in response to a specific challenge, be it the threat of Hitler or the threat ofCommunism. In most cases, however, there was a societal threat involved. Once the task was accomplished, the threatvanquished, the public political support rapidly dwindles, priorities change, funding shifts – sometimes dramatically.

What I am attempting to promote here is a major paradigm shift: changing our thinking about how mass-scale projectsare funded and accomplished. The USA no longer has any major threats to its security and stability. Given that, politicalwill to accomplish grand-scale projects via the public purse is far more difficult to gather and retain than it would be underconditions of threat or crisis. The American body politic has devolved into competing subgroups of special interests, allvying for their piece of the pie. The only major bloc left consists of all those receiving entitlement payments.

Fortunately, we can bypass all that D.C. infighting and use the power of the strongest economy ever created to ouradvantage. Lets take another look at the NASA numbers, in the chart on the following page:

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The first like is the NASA budget, 1970-2000, adjusted for inflation. The second line is 10% of that budget. For thesake of argument, I am positing that ANY government bureaucracy’s budget has, at minimum, a 10% “fluff factor” builtinto it. This is not cynicism – this is the conclusion of many DC-watchdog groups and think tanks such as the HeritageFoundation, Taxpayers Union, Common Cause, and the Cato Institute.

The third line is the result, when I take 10% of NASA’s annual budget, and invest it in the equity markets, at an averagerate of 11%. It is a relatively simple compound interest calculation, not accounting for market fluctuations, or changesin capital gains tax laws. Even so, the results are impressive. After 30 years of relatively mundane investing, NASAwould be able to fund itself entirely for 6 years, without taxpayer contribution of any kind! If we begin to manage thoseassets far more aggressively, using Peter Lynch’s Dow Dividend approach, or David and Tom Gardner’s “Foolish Four”strategy, long-term returns as high as 23% annually can be achieved – and indeed, ARE being achieved today bymillions of savvy investors.

Of course, this sort of thing is not going to happen with a government agency in our lifetimes. This was a sort of thoughtexperiment to prove a point. We can’t even compel NASA to set aside 1% of it’s annual budget to research humans-to-Mars technologies, although R & D is part of it’s mandate! Governments simply don’t think that way – and that is whywe must. Staying in the game for the long haul is the only reasonable way that humanity will ever have an opportunityto settle a new world.

So what should we do? Simply put, we should invest – as many of us as possible – all over the world, any way we can.We should get involved in commercial funds, investment clubs, whatever it takes.

One example: Introduced at the Mars Society Convention in Toronto in 2000, was a concept called the Ares Fund. Itsproponent, Clifford McMurray, suggested that although the Mars Society should always seek out and develop whateversources of funding that make themselves available, that the membership as a whole might set a great public example bypaying for it themselves, i.e., by investing a small amount of dollars in a long term fund, as a sort of ultimate backupplan. 4000 members times $250 per member – one time – for a total of $1,000,000 – into an investment pool, managedover the course of the entire 21st Century, if need be. The result at the end, however, would be enough cash to enablefuture Mars Society members to mount their own commercial missions!

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Our own “Colony Fund” venture capital initiative is also moving forward. When it is in place (by 2003), millions ofsmall investors all over the world will be able to invest a small amount over a long term, to help build the commercialand technical infrastructure necessary to one day – perhaps 30 years hence – support planetary colonization.

But overall, as I have shown above, success always depends on three things:

Dedication, Faith, and Patience

Resources1. NASA2. U.S. Office of Management and Budget3. U.S. General Accounting Office4. The Motley Fool (David and Tom Gardner) – for their 30-year stock market chart

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Torus Or Dome: Which Makes The Better Martian Home

Gary C. FisherAnd members of the Independence Chapter of The Mars Society

[1999]

AbstractMany traditional above ground Martian colony designs have used dome structures, usually constructed from a flexiblespherical membrane and inflated, to enclose the buildings of the colony. This paper will compare inflated sphericalstructures to inflated toroidal structures from the standpoint of internal volume, surface area, stresses, materialrequirements, stability, radiation shielding and safety.

I. Space Architecture as ImaginedIn Figure 1 we see an example of how space colonies were envisioned to look. This picture, from Islands In Space TheChallenge of the Planetoids1 published in 1964, is indicative of the role domes have been imagined to play in shelteringhumans on alien worlds.

Figure 1

Note the huge size of these domes. They must be several kilometers in diameter and several hundred meters high. Notealso the separation of residential, industrial and recreational spaces. Pictures such as this have inspired a generation ofhopeful space colonists. Unfortunately, they do not represent a realistic future for Mars for reasons to be discussed shortly.

II. Design Criteria for a Mars HabitatWe can divide the important considerations for a successful design into three main areas:

• Environmental• Habitability• Construction

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Gary C. Fisher; P.O. Box 694 Bryn Athyn, PA 19009; E-mail: [email protected]

Figure 2

Note: The lower density of the Martian atmosphere (1% of Earth’s) means that the wind loading on Mars for a givenwind velocity corresponds to an Earth wind velocity roughly 10 times smaller and a wind loading 100 times smaller.

Environmental ConsiderationsLet us consider the effect these various environmental factors have when designing a surface habitat. Figure 2 givessome comparisons between the environment of Mars and Earth. In Figure 3 the pictures of the Earth, Moon, and Marsgive their relative diameters.

Figure 3. The relative diameters of the Earth, Moon, and Mars

The lower gravity of Mars must be considered to be an overall benefit allowing for easier transport of building materials,and erection of structures, with a lessening of the innate dead loads.

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The low Martian atmospheric pressure dictates that for all inhabited structures the internal pressure loads exceed thestatic or live loads and therefore dictate the overall engineering of the structure. This inevitably leads to designs thatserve well as pressure vessels, e.g., spheres, and spherically end capped cylinders.

The intense radiation environment of Mars rules out many materials that deteriorate in a harsh ultraviolet, Galactic CosmicRay (GCR) and Solar Proton Event (SPE) radiation environment. It also means that a sufficient thickness of the chosenmaterials be used to shield the inhabited space from dangerous levels of radiation. For inflated structures the applicationof shield material to the outside of the structure has the benefit of countering the internal pressure. Townsend and Wilson2

have shown that a covering of around 20 g/cm2 of Martian regolith provides sufficient GCR and SPE shielding.

The extreme cold of Mars dictates materials that do not become brittle at the low temperatures and remain dimensionallystable across the large range of temperature.

Mars is a world of strong winds with a light touch. Wind loading is not a design consideration; the internal / externalpressure differential is by far the most important structural loading concern. Of more concern, is the abrasive nature ofMartian dust and the effect this may have on rotating machinery, e.g., air lock door mechanisms.

When dealing with inflated structures, which is the focus of this paper, the planet’s surface texture is an importantconsideration. The Viking and Pathfinder probes have both revealed a world with a very rocky surface. To avoidpuncture it appears that some site preparation, consisting of removing large sharp rocks, may be necessary beforeinflating any large structure on Mars.

Habitability ConsiderationsHabitability considerations mean those factors that affect the psychology and physical well being of the inhabitants.

People are territorial and require a space of their own. In order to maintain social order it is essential that people be ableto have dominance over some territory of their own. Factors that are important include the size of spaces; spatial variety,which is essential to our sense of freedom; views, which make spaces feel larger and provide a depth of field; naturallight and fresh air, which counter depression and the illnesses associated with “sick building syndrome.” Volume, andlots of it, is what is needed. Current estimates are that people need the following minimum number of square feet ofspace per use per person: Private space – 250, Work – 100, Recreation - 150, Assembly – 50.3 In addition we can expectthat a Martian habitat will require additional space for food production and life support as well as common space, e.g.,corridors and stairs. We must also consider that ceiling height and door heights may need to be higher in a low genvironment. Inflatable habitats appear to have the edge in providing the largest, undivided interior volumes per unitmass of structure (excluding shielding).

The interior environment of the habitat can be severely degraded by a bad choice of materials. Out gassing of dangerousor noxious chemicals, or the production of secondary radiation are two critical factors when choosing materials.

Construction ConsiderationsThe final consideration is construction requirements. Here I list a few construction constraints, some originallyidentified for the Moon, but of relevance to Mars as well.4 These apply either to a structure imported from Earth ordeveloped locally:

• Minimize need for heavy equipment (probably not available, and excavation and grading are difficult because of lackof traction)

• Minimize need for power• Avoid hydraulic systems because out gassing can contaminate surroundings and because the near vacuum is hard on

seals• Design with as few field joints as possible• Each component must be designed to be handled by one or at most two astronauts

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• Components must be compatible with astronaut’s gloved hands• EVA time is limited• Easy to integrate life support, power and lighting systems, and other architectural elements such as, floors, walls,

airlocks, windows, etc.

In addition inflatable structures have certain material requirements:• High strength – need to be able to withstand a pressure differential of probably a maximum of 15 psi• Durable• Easily folded• Low Cost• Low Mass• Do not change properties or age excessively in the Martian atmosphere• Withstand radiation without causing secondary radiation• No off-gassing to interior• Withstand Micrometeoroids (rip stop, easy to patch)

III. Review of Space InflatablesUses:Until the advent of the TransHab project inflatable habitats had not gone much beyond the paper design stage. However,inflatables have a long history in space dating back to some of the earliest space projects. Some of the uses of inflatablesinclude:

Atmospheric studies – Upper Atmosphere Density Obtained from Falling Sphere Drag Measurements – Dec. 1962

Antennas – Echo I – 1960, Echo II – 1964; Project Big Shot (the first phase in the NASA program leading to a globalcommunication system using rigidized inflatable spheres equidistant and in orbit around the Earth) – 1961; Design andInvestigation of Low Frequency Space Antennas – Jan. 1964; Inflatable Antenna Experiment on STS-77 – 1996

Solar Collectors – Deployment and Rigidization Test of a Large Inflatable Solar Collector – 1967

Propellant Bladders – RCA MPU Bladder Development program Apr.-July 1963

Trusses / Tunnels / Hangers / Solar arrays, etc. – Vacuum Deployment Tests on an Expandable Crew Transfer Tunnel –1966; Inflatable Torus Solar Array Technology (ITSAT) Program – 1991

Decelerators – Investigation of an Attached Inflatable Decelerator System For Drag Augmentation of the Voyager EntryCapsule at Supersonic Speeds – 1968; Deployment and Performance Characteristics of Attached Inflatable DeceleratorsWith Mechanically Deployed Inlets at Mach Numbers from 2.6 to 4.5. – 1972; Pathfinder 1997

Habitats – TransHab module for attachment to the International Space Station

Decoy – Inflatable decoys have been used in ICBM tests. Details on these projects remain mostly classified. One ofthe major manufacturers of space inflatables is L’Garde Inc. of Tustin, CA, which has been making decoys since 1971.

TechnologyThe materials used in inflatable technology depend a lot upon the end use of the structure. Early on, aluminizedpolyester, e.g., Mylar, was used for the Echo communications satellites. Later on, resins that harden in the spaceenvironment, such as developed for a project to create an inflatable self-rigidizing space shelter and solar collector fromhoneycomb sandwich in 1963-1964, were created. Inflation for these types of structures was only required to achievethe final shape, after which the material would harden to maintain the shape even if the initial, low pressure, inflation

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gas escaped. This includes technologies such as plasticizers that boil off, and reactions that result in the final cross-linking in a matrix resin of a fiber reinforced composite.

For habitats such as TransHab, laminated materials are being considered. The primary concerns being resistance tomicrometeorite penetration, and retention of the internal pressure.

There was even a metal bellows concept developed by Tracor, Inc in 19925 that combined traditional aerospace designwith inflatable concepts. The pneumatically erected habitat was constructed like a bellows with the skin made of veryflexible and thin (.0007”) titanium foil attached to rigid stringers.

Other technological advances include dual wall construction.6 A dual wall structure achieves its final shape by inflatingthe space between to membranes or walls, rather than the interior space. The two major designs are pile fabric, called“Airmat” by Goodyear and “Rigidair” by Air Inflatable Products Corporation and “Wing tab” or I-Beam rib. In pilefabric many threads, in basically a drop stitch method, connect the membranes where the thread lengths are controlledto maintain a predetermined distance between the membranes. Wing tab fabric incorporates attachment flanges for theweb as integrally woven portions of the membrane material. Wing tab fabric looks like a large air mattress with I-Beamwebs holding the two membranes parallel. The stresses are evenly distributed and wing tab construction allows shapingof the structure into compound curves.

Inflatable Habitats – Advantages

• More volume per pound: 30-50% lighter than Hard Aluminum structures• Greater flexibility of interior arrangement• Large, continuous volume• Automated deployment / Simple assembly• Lower cost?• Structural dead loads and occupancy live loads are negligible• May better handle thermal stresses caused by temperature changes

Inflatable Habitats – Disadvantages

• Credibility: Unproven technology• Cost: Requires longer lead time to develop, little manufacturing infrastructure exists• Complexity: Need to resolve issues of durability, manufacture, deployment, maintainability and repair

IV. Sphere / Dome DesignsCase For Mars Designs(a) Dome from half buried sphere.(b) Dome with lower half with twice the radius of curvature of the upper

half.(c) Anchored tent dome.(d) Sphere held in place by berm with interior suspended decking.

Figure 4, from The Case For Mars,7 illustrate the fundamental problemwith a dome. The pressure in a dome acts as a force trying to tear thedome from the Martian surface. The forces acting on the circumferenceof a 50-meter diameter dome pressurized to 5 psi is 44 tons per meter!Dr. Zubrin has proposed several ways to address this. One is to create adomed space by filling a sphere half full of dirt in order to provide theinflated sphere with stability and a flat floor. Alternatively, to avoid such

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Figure 4

massive excavation (with the corresponding problem of transporting a massive quantity of regolith into the sphere) thesphere can be held stable by a berm, or the radius of curvature of the lower half may be twice that of the upper half. Ifa dome is to be used, then a significant amount of excavation is required in order to bury a skirt deep enough tocounteract the lifting force. To provide radiation protection all these designs include an additional externalunpressurized Plexiglas shield. Dr. Zubrin proposed two basic sizes: 50 and 100 meters in diameter.

Author’s Proposed Sphere / Dome DesignsHere are three design concepts by the author for an inflated spherical habitat.

The Chinapas Sphere:The first is based upon the idea of Chinapas, the floating gardens built by the Aztecs. In this design the flat floor of thedome is created as a floating floor, the regolith that would have had to be imported into the sphere being replaced bywater, which could be inserted by a through-wall fitting and a hose. As in the Aztec Chinapas, plants are allowed togrow roots through the floating floor into the water below. Figure 5 is a sketch of such a sphere.

The floating floor is supported bypressurized gas tanks containingsupplemental air in case of a loss ofpressure. The floor is made like a wovenmat, perhaps regolith treated to act likesoil. Plants of bamboo, covered with cangrow their roots through the floating floorto reach the nutrient rich water below.Occasionally mud must be pumped upfrom the bottom of the sphere to be spreadon the floating floor.

This design is probably limited togreenhouse spheres because of the highhumidity. Some form of flexible skirt mustbe attached at the interface of the floor andthe sphere dome to minimize evaporationaround the edge of the floor and to prevent

the floor from tipping if excess weight is placed near the periphery. For residence-type spheres the membrane of thelower half of the sphere may be designed to be thermally conductive while the upper half is thermally insulating. Underthese circumstances the water will freeze and the installed, nonfloating, floor should also be highly insulating so that thewater below does not melt. Given a ready supply of water, filling a sphere by pumping in water is much simpler thanimporting regolith. Lacking water, liquid CO2 could be pumped in and allowed to freeze into dry ice.

Cliffside Sphere:This next design, figure 6, simplifies the excavation required for the sphere. A site is located on a crater or cliff wallwhere explosive charges are placed into holes drilled in a semicircular pattern. When exploded the charges cause asemicircular depression along the crater wall or cliff to be created; the material being removed is blasted into the crateror onto the land below the cliff. Some minor shaping of the depression created will need to be done before the sphereis inflated into it. Rather than a flat floor, a terraced interior is created by tunneling into the regolith at the back of thesphere at multiple levels. As the mine tailings are dumped into the sphere and bulldozed into a terrace level, additionalinhabitable space is being created in the tunnels. By locating the sphere in this manner significant radiation shieldingis provided by the adjacent regolith.

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Figure 5

After inflation, crews use pressure doorsincorporated into the membrane to beginexcavating tunnels into the cliff face.Beginning with the lowest level regolith isexcavated and the tailings dumped into thesphere to create the first terrace. Higherterraces result in shorter tunnels since lessmaterial is required. The tunnels provideadditional inhabitable space and a refuge incase of loss of sphere membrane integrity.

Hydrosphere:This next design, figure 7, is a variation onthe Chinapas design. It utilizes the pressuredifferential between the exterior and interiorof the dome to fill the space between the twowalls of the sphere full of water. Theprinciple being applied is that of the U-tubebarometer. The interior air pressure forces

the water below the floating floor through a hole in the bottom of the inner wall up into the space between the two walls.The interior air pressure also supports the weight of the water in the wall above the floor. The space between the twowalls is chosen to provide the optimal radiation shielding while transmitting sunlight. A rigid wall, rather than a flexiblewall may be preferable for this design. A simpler structure might consist of a dual wall rigid cylinder with a flat roofcovered with regolith.

The pressure of the hab atmosphere pushes outin all directions including pushing on thefloating floor and the water beneath it. Thisforces water through the hole at the bottomcenter of the inner membrane and into the spacebetween the two membranes. The outermembrane has a hole at the top that puts thewater into communion with the exterior, low,pressure Martian atmosphere. In order toachieve hydrostatic equilibrium the watercolumn will rise above the floor of the sphereproviding a water radiation shield.

The height, h, that water will be raised by the pressure differential can be calculated as:

h = (H2 – H1) = (P1 – P2) / (rho*g) = p / (rho*g)

where: h = the height difference H2 – H1P = the pressure difference P1 – P2rho = the density of water = 1000 kg/m3 (at 0 degrees Celsius)g = the acceleration of gravity on Mars = 3.711 m/s2

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Figure 6

Figure 7

If the internal pressure is P1 = 8 psi = 55 kPa and the external pressure is P2 = .07 psi = 0.49 kPa the resulting height his 14.7 meters!

Other DesignsCylindrical Fabric-Confined Soil Structures:Richard Harrison, of TRW, Inc. has proposed8 creating fabric tubes that are filled with dirt in order to create arches,which help counteract the internal pressure, hold the inflated structure in place and provide some radiation shielding. Anumber of such arches can be used to confine, and in cases of loss of internal pressure, support an inflated sphere.

Note: The reader is directed to the source paper for illustrations of this concept.

Hexmars-II:Prairie View Agricultural and Mechanical College’s Hexmars-II concept9 consists of six inflated spheres partially buried.Shaped charges are used to do the initial excavation. An interior telescoping core post is put in place followed by inflationof a Kevlar membrane. The crater is back-filled with regolith, the exposed upper portion of the sphere covered withrigidized foam and then covered with sandbags. This concept includes an ingenious non-penetrating connector forconnecting cables to anywhere on the inside of the dome. Three floors are attached to the central core post.


Inflatable Lunar Habitat:The inflatable lunar habitat design10 from a joint NASA / Texas A&M university study of 1989 came in two designs,both incorporate a 16-meter diameter inflated sphere, one third below grade and the upper two thirds covered with alayer of regolith for radiation and meteoroid shielding and thermal insulation. One design provided an exterioraluminum frame to support the regolith shield in case of loss of internal pressure, the other design assumes the regolithshield is self-supporting. The interior was designed to have 5 floors and accommodate a crew of 12. This studyprimarily looked at the mass requirements of the aluminum structural elements. A rough calculation of the effect ofMars gravity on the design was done.


LUNAB:The LUNAB design,11 developed at the Italian Affiliate Campus for Space Architecture of the International SpaceUniversity in association with the Shimizu Corp. of Tokyo and Binistar Inc, of San Francisco, began with the samedesign requirements of the Texas A&M 1989 study but addresses the excavation question in a unique way. In this designof a self-constructing space system the 16-meter diameter sphere has a central core post containing an Archimedeanscrew. By some undefined method the screw is rotated and penetrates the regolith transporting material up the centralcore and then expelling it through a cupola at the top over the inflated sphere providing a radiation shielding coating.Some additional excavation would probably be required, but the Archimedean screw would anchor the structure andautomate the covering with regolith. Five levels of floors are ingeniously folded up against the central post from whichthey deploy.


V. The TorusA torus, figure 8, is a geometrical shape familiar in everyday life as the shape of a doughnut or bagel. In fact, it waswhile sitting by a swimming pool and observing a beach ball and an inner tube floating by that the thought first cameto the author that the inner tube (toroidal) shape might be preferable to the beach ball (spherical) shape for an inflatedhabitat. Geometrically the standard torus is parameterized as a surface of revolution: a circle is revolved around an axis.

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The general equations for such a torus are:

f(u,v) = [(a+b*cos(v)) * cos(u) , (a+b*cos(v))*sin(u) , c*sin(v)]

Radius r of revolving circle. Distance Rfrom center to axis of rotation.

Area = 4p2Rr Volume = 2p2Rr2

u cut v cutFigure 8

The stresses (σ), Figure 9, on a torus can be calculated using the following formula:12

Circumferentially around the torus the stress is the same as in the surface of a sphere:

σ = Pr/2 where P is the internal pressure

For the stress around the membrane from the outside to the inner hole the stress is calculated as:

σq = (Pr/2)((2+r sin q/R) / (1+ r sin q/R))

Figure 9VI. Torus DesignsThe torus shape was adopted for the 1975 Stanford University space colony design for a large space habitat for up to10,000 people. The 1975 Summer Faculty Fellowship Program in Engineering Systems Design sponsored by NASAand the American Society for Engineering Education (ASEE), convened at Stanford University and the NASA AmesResearch Center. Nineteen professors of engineering, physical science, social science, and architecture, three volunteersfrom academe, industry, and government, six students, a technical director, and two co-directors worked for ten weeksto design a system for the colonization of space. The technical director was Gerard K. O’Neill. Their final reportappeared in 1977 as NASA Special Publication SP-413.13 Their prototype colony is known as “the Stanford Torus.”The Stanford torus was designed as a rigid, not an inflatable, structure. However, the final report of this projectrepresents the best, most detailed discussion of the issues facing a large space habitat with particular reference to atoroidal-shaped structure.

The torus, as a shape for an inflated habitat, appears to have been originated by Peter Kokh14 and, independently, byLawrence Livermore National Laboratory under a project led by Dr. Lowell Wood. ILC Dover did a follow onconfiguration analysis and design study for Livermore.15 This study resulted in two toroidal designs for thedevelopment of standardized modules that could be combined to create larger stations similar to the ISS. The TransHabmodule, developed at the Johnson Space Center, built upon the Livermore / ILC Dover studies. TransHab was designedto provide additional livable space on the Moon, Mars, or as an attachment to the ISS.

The author’s pool side epiphany resulted in roundtable design effort by members of his Mars Society Chapter that leadto the design of the Independence Torus designed to accommodate a small settlement on Mars.

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The Lunar Hostel, a.k.a. MoonbaglePeter Kokh’s seminal paper discussed the concept of a lunar hostel, “an inexpensively equipped habitat with lots ofelbow-room that needed only to be hooked up to the cranny-jammed expensive equipment of a docked visiting vehiclein order to function as a complete base.” This concept is not limited to “hostel” use. The core could contain all the“works” needed for a full-function base.

Figure 10 (Reproduced with permission)

Figure 10 shows a shielded Moonbagel (the name given by David A. Dunlop) deployed in a suitably sized crater to easeplacement of shielding overburden. A core module in the center contains the electronics, power, plumbing, heating /cooling, air / water recycling, communications, and galley. The hollow ribs are filled with a rigidizing foam. The torusis for sleeping, recreation, dining, exercise and other functions needing lots of space. A rigid central core extendsupward through the regolith shield and provides an exit for suited EVA. A tunnel through the regolith shield providesa place for vehicles to dock.

TransHabThe concept for TransHab, figure 11, originated at NASA’s Lyndon B. Johnson Space Center in 1997 as a possibledesign for an inflatable living quarters on future Mars-bound spacecraft.

The structure is, like the Moonbagel, a hybrid having a rigid core with an inflated toroidal outer component. TransHab’sfoot-thick inflatable shell has almost two dozen layers. The layers are fashioned to break up particles of space debrisand tiny meteorites that may hit the shell with a speed seven times as fast as a bullet. Debris protection is achieved bysuccessive layers of Nextel, spaced between several-inches-thick layers of open cell foam, similar to foam. The Nexteland foam layers cause a particle to shatter as it hits, losing more and more of its energy as it penetrates deeper. Theouter layers protect multiple inner bladders, made of a material that holds in the module’s air. The shell also providesinsulation from temperatures in space that can range from plus 250 degrees Fahrenheit in the Sun to minus 200 degreesin the shade. Many layers into the shell is a layer of woven Kevlar that holds the module’s shape. Three bladders ofCombitherm, a material used in the food-packing industry, hold the air inside. The innermost layer, forming the insidewall of the module, is Nomex cloth, a fireproof material that also protects the bladder from scuffs and scratches.

Level 4 – Pressurized tunnel Figure 11 (Courtesy of NASA)Level 3 – Crew health careLevel 2 – Mechanical room and crew quartersLevel 1 – Wardroom and galley

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Independence TorusThe Independence Torus, figure 12, is the result of a design project of the Independence Chapter (Philadelphia, PA) ofthe Mars Society. The design assumes an R of 15 meters and an r of 10 meters for an overall diameter of 50 meters.The structure is segmented into quadrants, each of which may be isolated by interior pressure doors from the adjacentquadrants. The whole structure is protected from UV and other radiation by a Plexiglas shield supported on guy wiresdescending at an angle from a central mast. The Plexiglas panels can be hoisted, like sails, to the top of the tower bypulling on lines for that purpose. In the illustration two rovers are cooperating in “hoisting the shields.” The shield alsoprovides minimal micrometeorite protection as well as protection from dust. A more temperate microclimate shoulddevelop under this tent. The mast can be used as a radio tower, weather station, or even, as shown, a mooring mast fora lighter-than-air craft. While not shown in the illustration, a layer of regolith could be applied over the structure.

One quadrant, the one that would receive the most sunlight, is designed with transparent membranes and functions as agreenhouse. The greenhouse quadrant may function like an Aztec Chinapas and have a floating floor.

The crew living quarters would be divided between two separate quadrants. One quadrant would contain apartmentsfor half the crew along with the galley space; another quadrant would contain the apartments for the other half of thecrew along with the recreational space. The final quadrant contains the mechanical systems, the main air lock, workingspace, and storage.

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Figure 12. The Independence Torus – Rendering by Tim Bauer

VII. Advantages of the TorusThe torus has a number of advantages over a sphere.

• A torus has a stable footprint (will not roll away)• More easily segmented for safety• Provides a natural shape for circulating the interior air• Not as tall for its volume allowing for easier covering with regolith for radiation or other shielding• More floor area with the maximum headroom• Less inflation gas required for comparable floor area• Less regolith must be imported into the structure to create the level floor

While for a given diameter a sphere has a greater volume, much of this volume is not usable unless additional floors are created.

As table 1 shows, the amount of floor area can be similar for sphere and torus of the same diameter; however, a torusmay have significantly less surface area. While this reduced surface area, nearly a third in the case of the 100 meterdiameter comparison in the table, translates into reduced mass, it does come at the expense of less interior volume.However, the lost volume is not usable in a large diameter sphere unless a structure is built in the sphere to createadditional floors. This flooring will also add mass that will need to be imported from Earth and that will requireadditional construction time. The breathable gas mixture that must be created to inflate a sphere is correspondinglymuch greater because of this additional volume.

Table 1

Note: Floor Area is the surface area created by filling the torus or sphere half full of regolith. The sizes were chosen tocorrespond to the sphere sizes discussed in Zubrin’s The Case For Mars.

VIII. ConclusionWhile not yet as developed as the sphere (dome) from a conceptual standpoint, the torus, particularly an inflated toruswith a solid core, appears to have been accepted as the preferred configuration for at least small habitats. A torus hassignificant advantages over a sphere, most importantly, for structures transported from Earth in the mass to floor arearatio. Significant savings are also to be had in construction time and difficulty, due to the innate stability of the torusand the significantly less inflation gas that must be used to inflate, and the regolith that must be imported into, a torusversus a sphere of similar floor area. Safety is enhanced by the relative simplicity of segmenting a torus into separatepressure compartments.

References1. D. M. Cole and D. W. Cox with Forward by Willy Ley, Islands In Space Chilton Books, Philadelphia, 1964).2. L. W. Townsend and J. W. Wilson, “The Interplanetary Radiation Environment and Methods To Shield From It,” in Strategies For Mars: A

Guide To Human Exploration, ed. Carol R. Stoker (American Astronautical Society by Univelt, San Diego, 1996), pp. 315-16.3. R. Pfeifer, “Lunar Habitats – Places for People,” in Engineering, Construction, and Operations in Space III, Vol. 1, (American Society of Civil

Engineers, New York, NY, 1992), pp. 183-88.

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4. S. W. Johnson, K. M. Chua, M. Schwartz, and J. O. Burns, “Architectural Considerations In Design of Lunar-Based AstronomicalObservatories,” in Engineering, Construction, and Operations in Space V, Vol. 2, (American Society of Civil Engineers, New York, NY, 1996),pp. 871-79.

5. S. Bradley (Tracor, Inc.), “Pneumatically Erected Rigid Habitat,” in Third SEI Technical Interchange: Proceedings, (NASA, Lyndon B.Johnson Space Center, 1992), pp. 592-596.

6. H. Q. Bair, W. H. Fischer (Air Inflatable Products Corp.), “Dual Wall Inflatable Structures For Space Oriented Applications,” in AFSC,Wright-Patterson AFB, Ohio Aerospace Expandable Struct., 1966) pp.785-802.

7. R. M. Zubrin, The Case For Mars: The Plan to Settle The Red Planet and Why We Must, (The Free Press, New York, NY, 1996)8. R. A. Harrison, “Cylindrical Fabric-Confined Soil Structures,” in Engineering, Construction, and Operations in Space III, Vol. 1, (American

Society of Civil Engineers, New York, NY, 1992), pp. 123-34.9. I. Sabouni, Prairie View A&M University, “Design and Development of the Second Generation Mars Habitat,” in USRA, Proceedings of the

8th Annual Summer Conference: NASA/USRA Advanced Design Program, 1992), pp. 228-36.10. P. K. Yin (Texas A&M Univ.), “A Preliminary Design of Interior Structure and Foundation of an Inflatable Lunar Habitat,” in NASA/ASEE

Summer Faculty Fellowship Program Vol 2, (NASA, Lyndon B. Johnson Space Center, 1989), pp. 26-1 – 26-10.11. D. Bedini, “Self-Constructing Space Systems,” in Engineering, Construction, and Operations in Space V, Vol. 2, (American Society of Civil

Engineers, New York, NY, 1996), pp. 1032-37.12. M. Roberts, “Inflatable Habitation for the Lunar Base,” in The Second Conference on Lunar Bases and Space Activities of the 21st Century,

Vol 1, (NASA, Lyndon B. Johnson Space Center, 1989), pp. 249-253.13. R. D. Johnson and C. Holbrow, editors. Space Settlements: A Design Study. NASA Scientific and Technical Information Office, 1977. Special

Publication 413: authored by the participants of the 1975 Summer Faculty Fellowship Program in Engineering Systems Design at StanfordUniversity and NASA Ames Research Center.

14. P. Kokh, D. Armstrong, M. R. Kaehny, and J. Suszynski, “The Lunar “Hostel” An Alternate Concept for First Beachhead and SecondaryOutposts,” presented at ISDC ‘91, (San Antonio, TX, 1991) http://www.lunar-reclamation.org/hostels_paper1.htm

15. D. Cadogan, J. Stein, M. Grahne (ILC Dover, Inc.), “Inflatable Composite Habitat Structures for Lunar and Mars Exploration,” 49th

International Astronautical Congress Sept 28-Oct 2, 1998, Melbourne, Australia http://www.ilcdover.com/WebDocs/habitats.pdf

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The Effects of Upright Lower Body Negative Pressure CycleErgometry Training on Vo2max and Endurance

Joe O’Saben; George D. Swanson[1999]

AbstractTravel to and residence at Mars may require the use of a Lower Body Negative Pressure (LBNP) training device tomaintain fitness. The LBNP device pulls body fluids into the lower body so as to simulate an Earth-like gravity vector.The purpose of this study was to determine if a cycle ergometry training program using LBNP would cause a greaterincrease in VO2max and endurance, than an identical training program that did not use Lower Body Negative Pressure.

VO2max and endurance were determined on a cycle ergometer and on a treadmill using the Bruce protocol. The subjectswere matched according to VO2max and divided into experimental and control groups. The subjects then trained threetimes per week for 8-weeks at about 70% VO2max. Following the eight weeks, they repeated the pre-test protocol. Eightvolunteers began the program, and 5 (3 study / 2 control) completed it. The results of the post-testing showed greaterincreases in VO2max in the study group compared to the controls, although the low number of subjects precludedstatistical analysis. The study group showed increases in VO2max of 4.8%, 16.25%, and 7%; while the control groupshowed increases of 5.9% and 2.4%. The results from the endurance test did not show improvement in either group.

These results suggest that training under LBNP conditions may be useful to enhance fitness in 1 G. Similarly, in 0 Gor 1/3 G, training with LBNP may simulate a more Earth-like training condition because fluids are shifted to the legs asthey are in 1G. The consequence may be an increase in blood and plasma volume – the traditional Earth-like trainingeffect. A higher level of aerobic fitness may be possible using the LBNP training device while in and traveling to theMartian environment thus increasing Martian work capacity and facilitating reentry into a 1 G environment.

IntroductionTraveling, living and working in outer space creates physiological and medical concerns for astronauts. Short stays intospace affect the astronauts’ fitness levels, and long stays in microgravity leave returning astronauts unable to stand.Lower Body Negative Pressure (LBNP) devices have been used to mimic the influences of gravity on the body forstudies using extended bed rest to simulate microgravity, in efforts to find ways that would allow astronauts to maintaintheir fitness levels while in space (Lee et al. 1997; Hargens et al. 1994; Murthy et al. 1994). These studies have shownthat supine LBNP exercise simulates upright exercise in maintaining submaximal exercise responses. Furthermore, in1968, Cooper and Ord observed that upright exercise under LBNP conditions might produce a training effect.

Therefore, the purpose of this study was to determine if an eight-week upright LBNP cycle ergometry training programwould produce a training effect on VO2max and endurance and relate these results to long term space flight.

Review of LiteratureThis section will examine the literature associated with Lower Body Negative Pressure training, and its effects onVO2max and endurance.

Astronauts returning from space flight lasting one to two weeks typically find themselves to be orthostatically intolerantupon returning to Earth (Hargens and Watenpaugh, 1996). In an attempt to maintain, or even improve, the physicalconditioning of astronauts exposed to a microgravity (space) environment, researchers have tried to train subjects in asimulated microgravity environment on Earth, due to the difficulty of performing this research in space. The two mostcommon ways that microgravity is simulated are bed rest and Head-Down Tilt (HDT). With these methods, fluidredistribution and cardiovascular deconditioning approximates that found during space flight. Subjects undergoing bedrest can be placed supine into a Lower Body Negative Pressure chamber to exercise without returning to a standing

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Joe O’Saben & George D. Swanson; California State University, Chico, CA 95929-0330; Phone 503-898-4841; Fax 530-898-4932;[email protected]

position effectively maintaining the simulated effect of microgravity. While supine within the LBNP chamber, fluids andblood pressure gradients are redistributed in the body to approximately that of a 1G (Earth) environment. Exercise in thechamber can be on a vertically mounted treadmill or cycle ergometer. In the case of the treadmill, pulleys are used aroundthe legs to remove the vertical gravity vector, which is not present in space. It has been demonstrated that trainingresponses under supine LBNP conditions closely resemble the training responses of an upright 1G training program.

Hargens et al, (1991) compared footward forces produced in a supine LBNP environment to standing, and found themto be similar, thus showing the effectiveness of supine LBNP to approximate those forces when standing. If supineLBNP forces are similar to normal upright forces, then it may follow that upright LBNP forces will be greater than 1G,and that upright LBNP exercise will place an additional stress on the body.

Murthy and co-workers (1994) found that supine LBNP exercise closely resembles that of upright exercise. Theymeasured footward force, muscular pressure of the soleus and tibialis anterior, calf volume, heart rate and bloodpressures in both supine LBNP and upright 1G conditions. They concluded that supine exercise against 100 mm HgLBNP provides similar muscular stress as the same exercise upright against 1G. Additionally, they found that supineLBNP provides greater cardiovascular stress than upright 1G exercise, evidenced by a significantly higher heart rate (99+ 5 to 81 + 3 beats per minute). Also, and possibly related to the increased heart rate, the calf volume was significantlyincreased by 3.3 + 0.5% during LBNP exercise, while it did not increase significantly during 1G exercise.

Eiken (1988) also observed significantly higher heart rates during supine LBNP cycling exercise than supine exercisewithout LBNP, in addition to significantly lower blood lactate levels in the LBNP group. Oxygen uptake was found tobe 10% lower in the LBNP group, and it rose at a much lower rate than the control group. Cycling endurance was foundto be higher in the LBNP group, but still less than similar upright exercise. He concluded that supine LBNP exercise isa “valid and useful model of upright exercise” (p. 775).

Lee and co-workers (1997) found that supine LBNP exercise is able to maintain the exercise responses as well as uprightexercise in subjects undergoing five days of bed rest. Pre- and post-bed rest exercise testing showed significantelevations in heart rate, respiratory exchange ratio and minute ventilation in the control group, who did not exercise, butsimilar values between the upright exercisers and those who exercised supine with LBNP in all variables tested. Whilethis is useful for the space program, it also suggests that supine LBNP exercise occurs at a simulated 1G.

In comparing supine exercise with and without LBNP, Eiken and Bjurstedt (1985) found that exercise with LBNP didnot have a significant influence on heart rate compared to exercise without LBNP during graded exercise on a cycleergometer at workloads of 0, 50 and 100 watts for four minutes each. Significant decreases were found however, incardiac output, stroke volume, and mean systolic ejection rate at all workloads. This study also showed that leg exerciseaids in returning blood to the heart, as stroke volume with LBNP increased considerably from resting values, andcontinued to increase during exercise, whereas, during exercise without LBNP, stroke volumes decreased withincreasing loads.

Submaximal VO2 and ventilatory thresholds were found to be lower in supine LBNP exercise when compared to uprightexercise, however, the difference was not significant (Hughson et al, 1993). Significant decreases were found inVO2max and ventilatory thresholds between supine LBNP and upright exercise. At low or high work rates, heart rateswere found to be similar in supine LBNP and upright exercise.

Cooper and Ord, in 1968, compared upright and supine exercise during submaximal exercise with and without LBNP,and found significantly higher heart rates (184 to 173) were attained during the upright LBNP exercise. Cycling withoutLBNP had slightly higher, but not significant, VO2max and minute ventilation values. These cardiorespiratory changesare similar to those seen in a loss of physical fitness, or deconditioning. This study suggests that upright LBNP exercisecan produce a training overload that may accelerate a cardiovascular training response when compared to trainingwithout LBNP.

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The Effects of Upright Lower Body Negative Pressure Cycle Ergometry Training on Vo2max and Endurance

The research presented suggests that supine LBNP exercise is similar in training responses to normal upright exercise.Additionally, cardiovascular responses to supine LBNP are similar to, or even slightly higher than, normal uprightexercise, and it was observed that upright LBNP exercise produces higher heart rates and a deconditioning-like effect.The next logical step appears to be to try to ascertain the effects of an aerobic training program under upright LBNPconditions, to see if the LBNP induced deconditioning-like response will lead to an increased training response that canbe measured with VO2max and endurance testing. This may lead to an additional method for improving cardiovascularfitness that may be more effective than current methods.

MethodologyDuring the first week of the study, all the subjects underwent 3 pre-tests: (1) a cycle ergometry VO2max test, (2) a cycleergometry endurance test, and (3) a treadmill VO2max test.

The cycle ergometry (Monark mechanically braked cycle ergometer) VO2max test used the Chico cycle (similar to aBruce treadmill test) protocol, which terminated when the subject was unable to continue or maintain 60 rpm for 15seconds. During the last thirty seconds of each stage a Rating of Perceived Exertion, from the Borg revised scale(ACSM Guidelines, 1995) was obtained. Heart rate was measured with an EKG, and respiratory gases were measuredwith the metabolic cart (ParvoMedics TrueMax 2400, Parvo Medics, Inc., Sandy, UT) automatically during the test.Endurance was measured fifteen minutes after completion of the VO2max test. The test began with a 60-second warm-up at 60 rpm and 1 kp, then increased to 90 rpm and 2.5 kp. The test ended when the subject could no longer continueor maintain 90 rpm for 15 seconds. The treadmill test took place two days later and used the Bruce protocol (ACSMGuidelines, 1995). The same procedures were used as during the cycle testing. After all subjects had been tested, theywere ranked according to their cycle VO2max, and then divided into experimental and control groups. To distribute themevenly, the subject with the highest VO2max was placed into the experimental group and the subject with the secondhighest VO2max was placed into the control group. This procedure was continued until all subjects were assigned to agroup. The subjects were then contacted and training times were arranged that fit their schedules and preferred times.Times were scheduled that allowed one control and one experimental subject to train together to best utilize the lab time.A researcher was present for all training sessions to ensure compliance with the program and increase safety. Thetraining program was individualized to the subjects, based on 60-70% of their cycle VO2max test. Training protocolswere estimated using the leg ergometry calculation from the ACSM handbook (pg. 282).

VO2 ml/min = 3.5 ml/kg/min x kg BW + kgm/min x 2

Calculating 60, 65, and 70% of the individual’s VO2max and using a 60-rpm standard predicted the required workload.The subjects trained thirty minutes a day, three times per week for the next eight weeks starting at 60%, then increasingto 65% in the fourth week and 70% in the seventh week. The vacuum was maintained at 30 + 5 mm Hg, after it wasdiscovered during the first ride of each study subject that the planned 50 mm Hg vacuum resulted in dyspnea, light-headedness, and dizziness during the exercise period.

Following the eight weeks of training, the subjects repeated the cycle VO2max, cycle endurance, and treadmill VO2maxtesting, following the same protocols as the pre-test.

ResultsTable 1 shows the subjects characteristics and Table 2 shows the results from the pre- and post-tests. 8 subjects beganthe program, and 5 completed the 8 weeks of training.

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Table 1. Subject Characteristics

* 24 possible

Table 2. Study Results

The number of subjects completing the study was not suitable for a statistical analysis. However, the data imply thattraining in the LBNP box did have an effect on VO2max. The control group did not achieve improvements in VO2maxanywhere close to those in the study group. Subjects 4 and 5 were the most closely matched pair in the group. Theyalso trained at the same time and had similar attendance. Comparing their changes shows a three-fold increase in thestudy partner compared to the control. Subject 3, the most improved, also has nearly a three-fold increase over thehighest improvement from the control group.

The LBNP box did not appear to have an effect on endurance, as only 2 subjects showed any improvement. This maybe because the endurance test is more a test of power output, rather than cardiovascular fitness, or that the subjects weremore fatigued during the VO2max test because they cycled for a longer time.

Cardiovascular fitness improvements made while training on a cycle ergometer translated into an improved VO2max onthe treadmill as well. 3 of the 5 subjects had similar gains in VO2max on the treadmill test as they did on the cycle. Thisshows a lack of training specificity between the cycle and treadmill, and suggests that either a cycle ergometer ortreadmill could be used for training in the LBNP box.

ConclusionsThis study was designed to determine if upright training in a Lower Body Negative Pressure environment could producean ergogenic effect. Lower Body Negative Pressure training on supine bed rest subjects has been shown to approximateupright training, and that a supine LBNP environment produces similar gravitational-like forces when compared to anormal 1G upright environment. It had also been previously suggested that upright LBNP exercise might produce acardiovascular training effect.

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Eight subjects volunteered to be a part of an 8-week training program. They began with a pre-test to measure theircurrent VO2max and endurance times on a cycle ergometer, followed 2 days later by a Bruce treadmill test. The subjectswere then allocated to a study group with LBNP cycle training and a control group with normal cycle training. At theend of the 8-week training program, the subjects repeated the pre-test protocols. Five subjects (3 study / 2 control)completed the program. The cycle and treadmill VO2max scores of the study group were higher than those of the controlgroup, however the endurance times did not show any differences between the groups, and were improved in only 2subjects. The low number of subjects precluded a statistical analysis.

From an observational analysis of the results, it is apparent that statistical significance will require a larger study. Thenearly 3-fold difference in the study group suggests that an ergogenic effect did occur while training in the LBNP box.The lack of improvement in endurance times could be accounted for by the increased time the subjects went during theVO2max test, and that if not already fatigued, those times may also be increased. It could also show a difference intraining methods needed for aerobic capacity and power, because the endurance test is more a measure of power thanaerobic capacity.

These results suggest that training under LBNP conditions may be useful to enhance fitness in 1 G. Similarly, in 0 Gor 1/3 G, training with LBNP may simulate a more Earth-like training condition because fluids are shifted to the legs asthey are in 1G. The consequence may be an increase in blood and plasma volume – the traditional Earth-like trainingeffect. A higher level of aerobic fitness may be possible using the LBNP training device while in and traveling to theMartian environment thus increasing Martian work capacity and facilitating reentry into a 1 G environment.

References1. American College of Sports Medicine. (1995) ACSM’s Guidelines for Exercise Testing and Prescription (5th ed.) Media, PA: Williams &

Wilkens.2. Cooper, K. H. & Ord, J. W. (1968). Physical effects of seated and supine exercise with and without subatmospheric pressure applied to the

lower body. Aerospace Medicine, May, 481-484.3. Eiken, O. & Bjurstedt, H. (1985). Cardiac responses to lower body negative pressure and dynamic leg exercise. European Journal of Applied

Physiology, 54, 451-4554. Eiken, O. (1988). Effects of increased muscle perfusion pressure on responses to dynamic leg exercise in man. European Journal of Applied

Physiology, 57, 772-776.5. Hargens, A. R., Fortney, S. M., Ballard, R. E., et al. (1994). Supine treadmill exercise during lower body negative pressure provides equivalent

cardiovascular stress to upright exercise in 1 G. Aviation and Space Environmental Medicine, 65, 463.6. Hargens, A. R. & Watenpaugh, D. E. (1996). Cardiovascular adaptation to spaceflight. Medicine and Science in Sports and Exercise, 28, (8),

977-982.7. Hargens, A. R., Whalen, R. T., Watenpaugh, D. E., Schwandt, D. F., & Krock, L. P. (1991). Lower body negative pressure to provide load

bearing in space. Aviation and Space Environmental Medicine, 62, 934-937.8. Hill, A. V., & Lupton, H. (1923). Muscular exercise, lactic acid, and the supply utilization of oxygen. Quarterly Journal of Medicine, 16, 135-

171.9. Hughson, R. L., Cochrane, J. E., & Butler, G. C. (1993). Faster O2 kinetics at onset of supine exercise with than without lower body negative

pressure. Journal of Applied Physiology, 75, (5), 1962-1967.10. Lee, S. M. C., Bennett, B. S., Hargens, A. R., et al. (1997). Upright exercise or supine lower body negative pressure exercise maintains exercise

responses after bed rest. Medicine and Science in Sports and Exercise, 29, (7), 892-900.11. Murthy, G., Watenpaugh, D. E., Ballard, R. E., & Hargens, A. R. (1994). Supine exercise during lower body negative pressure effectively

simulates upright exercise in normal gravity. Journal of Applied Physiology, 76, (6), 2742-2748.

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Viewing the Martian Sunset

George A. Smith[1999]

Introduction[Image: “pale blue dot in a sunbeam” – Earth viewed by Voyager, from beyond the orbit of Neptune]Once upon a time, in a certain medium-sized spiral galaxy, there existed a world that was mistakenly called “Earth.”The name was mistaken in the sense that even from a great distance away one could immediately see that the place hada characteristic blue color. In Earth’s case, the blue indicated the presence of vast water oceans sloshing around muchof the planetary surface. It really should have been called not Earth, but “Oceania,” “Aqua,” or the like. The fact thatthe planet was misnamed did not make it unusual. In fact, one might expect any planet that evolved highly-complexlife forms to be misnamed, for the simple reason that the place would be named long before its inhabitants could makemeaningful comparisons to neighboring worlds and thereby understand what makes their world somewhat different.

Nor was there anything very unusual about the way Earth came into existence. About eight or nine billion years afterthe Big Bang, a cloud of interstellar gas and dust formed a protoplanetary disk. Over the course of about 150 millionyears the disk evolved into a star with a mix of rocky and gas planets revolving around it. Nothing very remarkablehere – just physics as usual, leading to typical planet formation.

What happened next was also routine: for about one billion years the Earth’s solar system was the scene of chaoticviolence, as the planets swept up leftover rocky debris. For a thousand million years, Earth was rocked by spectacularcollisions, including one giant impact that splashed debris into orbit around Earth, eventually forming the Moon.

Finally, the frequency of collisions diminished, and some interesting things began to happen. Namely, biological historybegan – about 3.7 billion year ago. This is not to chauvinistically imply that only biology is interesting. But the focuson biology highlights what does seem to be somewhat remarkable about Earth – the sudden emergence of a relativelyhigh-technology civilization; one sophisticated enough to realize that it’s living on a misnamed planet.

Life in a DayTo appreciate the abruptness with which high-tech civilization emerged on Earth, consider the time frame. Let’s call theperiod when simple life forms began in Earth’s oceans time zero. (In other words, we are putting aside the roughly 10billion years that preceded this point.) From time zero to the present is about 3.7 billion years. Let’s think of this 3.7billion years as a single day – a day representing the entire biological history of Earth.

Nothing much happened until 1.1 billion year ago, i.e., until nearly 5:00 in the evening of the day of life: single-cellfloating plankton developed the ability to sexually reproduce, a pivotal point in the “evolution of evolution.” TheCambrian explosion, a proliferation of life forms that some call the Big Bang of biology, took place 500 to 570 millionyears ago – 8:30 p.m. The dinosaurs developed, then disappeared in the fallout from the Chicxulub asteroid or cometimpact, 65 million years ago – 11:30 p.m. Finally, hominids we would recognize as human – creatures with primitivetools and the ability to use fire – appeared on the scene roughly 150,000 years ago – the last four seconds before midnight!

And what have we advanced hominids been doing for the past 150,000 years? Hunting and gathering, almost the entiretime. Finally, around 10,000 years ago – the very last 1/3 second of the day, we began to cultivate cereal grains androots, i.e., we invented agriculture.1 What we call the Enlightenment – the elevation of reason working through science– really began gaining momentum just 300 years ago – the final 1/100th second of the day of life. Even if we consideronly the most recent 150,000 years during which creatures recognizably like us have existed, the entire rise of high-techcivilization – beginning about 300 years ago – took place in the last 1/500th of that period of hominid existence.

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George A. Smith; 23 Lexington Ave No.1739, New York, NY 10010; [email protected]

The point of this perspectivizing is this: Our high-tech civilization has virtually exploded onto the scene, from out of along, slow biological history. If our minds and bodies are still deeply affected by biological processes that have beenshaping us for eons – and few would deny this – then the explosion of technological information is presumablysomewhat disorienting. At the very least, it seems reasonable to think we may need some extra help in order to take inand process this new information.

PathfinderIn 1997, barely a century past the horse-and-buggy era, we put Pathfinder on the surface of Mars. Somehow, we gotour human eyes up there, and were able to see panoramas like this one [Image: Pathfinder panorama, with Twin Peakson horizon], and this one [Image: Full sunset panorama, Twin Peaks to left] How did we manage to do this?

First, get a sense of the physical dimensions. Shrink the Sun to a 1-meter globe – the size of a large beach ball. Earththen becomes a large pea, 110 meters away – the far end of a soccer field. Mars becomes a small pea, 1-1/2 soccer fieldsaway in the other direction (at conjunction). And of course nothing is static: the peas are moving constantly in giantelliptical orbits, moving at high velocity relative to the sun and to each other.

On December 4, 1996, from this pea-sized planet Earth, a Delta II launched Pathfinder from Cape Canaveral. About ayear and a half later, Pathfinder reached Mars. This sums up in a few words a mind-boggling technical feat, madepossible through computerized guidance and communications systems which arose through decades of cumulativeadvances in many disciplines. At Mars, on July 4, 1997, Pathfinder executed its spectacular bounce-down landing, andcame to rest on a rocky plain. The air-cushion bags deflated, Pathfinder began to stir and unfold, science instrumentsemerged, and soon the images were coming back to Earth.

Pathway of an ImageTo say “the images were coming back to Earth” sums up in seven words a process of astounding technical finesse andcomplexity. What really happened – to give a slightly more accurate summation – is this: Light from that sun, and theMartian horizon, passed through the Pathfinder lens and color filter and fell onto a charge-coupled device (CCD). TheCCD divided the incoming light into a grid of hundreds of thousands of picture elements, and for each of these pixelsrecorded the brightness value. The process was repeated for a number of different color filters. The Pathfindercomputer then took these millions of pieces of information, converted them into digital code, and a radio transmitterthen relayed this bit stream back toward Earth.

Minutes later the bit stream reached one of the Deep Space Network’s giant antennas (in California, Australia, andSpain). The data was relayed to the Jet Propulsion Laboratory’s Image Processing Laboratory. Here, computersreformatted the bits into a two-dimensional image (again, think of the logistical complexity!), and the image wasrecorded on film and made available in digital form on the web. (And of course I printed out the image from the web,walked it over to my neighborhood print shop, and had it printed onto this transparency.) So that’s how we got thisimage. Simple as that.

Meanings of the ImageNow, let’s think about what is probably an even more complex question – what this image means to us. One thing thatcontributes to the complexity is the theme noted earlier, namely the sheer abruptness of the rise of high-tech civilizationon Earth. In the blink of an eye we’ve had a veritable Cambrian explosion of technology, the result being virtuoso featssuch as the production of this image. But when the image passes into our brains, an exquisite and very expensiveproduct of high-tech civilization enters the consciousness of hunter-gatherers. For more than 90% of our humanoidexistence, our brains, our thoughts, and our emotions have been evolving to make us very effective hunter-gatherers onthe surface of Earth. For images that come to us through our own eyes on Earth, we are very good at attributingappropriate meanings.

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But a view like this is something else. It confronts us with an image from what we know is an utterly unfamiliar place.And yet, it has elements that are very familiar. Faced with such a disorienting conflation of the familiar and the strange,we might almost be tempted to dismiss it as a dream landscape. But we know it’s not a dreamscape, but a very realplace. If we’re going to make sense of it, we may need some extra help.

The Overview EffectA book that explicitly addresses some of the complicated effects of the views available to us in the space age is TheOverview Effect by Frank White. White explores the ways in which our mental perspectives are shaped by our physicalpoints of view, in particular views from space such as this one [Image: Story Musgrave fixing the Hubble, with Australiain background]. He extensively interviewed astronauts, trying to gain a vicarious sense of how their space flightexperience – in particular their view of Earth from a great distance – may have affected their thoughts and attitudes.White concludes that astronauts often experienced what he calls the “overview effect.”

The Overview Effect is essentially a human reaction – mental, emotional, and psychological – to seeing the home planetfrom a great distance. It typically includes a sense of “transcendence,” for lack of a more specific word. According toWhite, the experience “varies with the individual, but typically includes a realization of the unity and oneness of theplanet, a strong emotional response to its beauty and fragility, and a shift from identity with specific countries to anidentification with the whole.2 Astronaut Russell Schweickart reported that, “[W]hen you come back there’s adifference in the world now. There’s a difference in that relationship between you and that planet and you and all thoseother forms of life on that planet.”3 Schweikart’s sense of renewed allegiance to “all those other forms of life on thatplanet” sounds a theme that is essentially environmentalist. Not surprisingly, the organizers of the first Earth Day, whichtook place less than a year after the Apollo moon landing, chose as their emblem an Apollo photo of the whole Earth.[Image: Earthrise (Apollo 8)].

Mythic ImagesAside from environmentalist use, the image of the Earth suspended in space has also been important as a pure symbolof exploration. The South African explorer and writer Laurens van der Post, in an essay he wrote when he was in hiseighties, suggested that we need a new symbol of exploration. He wrote that during the great seafaring ages, the imageof the profile of the Cape of Good Hope served as an important emblem, a sign that explorers had rounded the horn ofAfrica and were on their way back into familiar waters. In our time, wrote Van der Post, the image of the Cape of GoodHope is being supplanted by its psychological equivalent – the image of the whole Earth as viewed by the homewardbound Apollo astronauts.

Van der Post was a student (and biographer) of the great Swiss psychologist Carl Jung. Jungians tend to stress the powerof myths, symbols, and images, so perhaps it’s not surprising that van der Post seized on the Apollo image. Other Jungianshave as well, most notably the writer Joseph Campbell, whose work was deeply influenced by Jung. In Campbell’s bookThe Mythic Image,4 the very last illustration is the now-familiar image of the Earth photographed from Apollo 8.

The power of mythic narratives has always been reinforced by certain powerful images. Certain images seem richenough to contain intimations of the mythic narratives, and to prod our imaginations into adding further dimensions. It’sas if these images – due to their ability to conjure up mythical stories – start to function as stand-ins for the mythicalstories. For we humans, who thrive on mythic narratives, the images alone can thereby take on the power to organizeour experience and motivate our actions.

The Disappearing Solar SystemWe’ve been looking at the whole Earth image for 30 years now. Might it be time for some new iconic images ofexploration? If so, what would they be?

Frank White suggests that the next step, beyond the Overview Effect, is what he calls the “Copernican Perspective.” Ifthe Overview Effect is a realization of how the parts of the Earth fit into a single integrated system, the Copernican

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Perspective takes things to the next level – a deep understanding that the Earth in turn is a part of the solar system. Itis an intuitive realization that Copernicus was right: We are a part of the solar system as a whole. The solar system isour basic frame of reference.

This surely sounds plausible and potentially very powerful, but is there an image to go along with it? If the OverviewEffect is captured by the image of the whole Earth, what single image might capture the Copernican Perspective? Anatural tendency would be to simply pull the camera farther back, to encompass a grander, more spacious view. That’swhat Carl Sagan did in 1994 when he chose this image [Image: “pale blue dot in a sunbeam” (first image above)] forthe inside cover of his 1994 book, Pale Blue Dot. He captioned the image, “The Earth: a pale blue dot in a sunbeam.Photographed by Voyager 1 from beyond the orbit of Neptune.”

But compelling though an image like this may be, there’s not much of the solar system in it. Just Earth, and a beam ofsunlight. The problem is that there’s so much empty space in the solar system that it’s awfully hard to get much into asingle frame. Recall that if we shrink the Sun to the size of a large beach ball, the inner planets become small peas atthe other end of a soccer field. And the outer planets? Neptune would be the size of a marble, two miles away. Thereis simply no way to capture these sizes and distances in a meaningful image. Of course we could distort the sizes anddistances, as textbooks often do. But this wouldn’t be satisfying. Paradoxically, our belief that an image is an accuraterendering of the world, and not merely our fabrication, is part of what gives it mythic power.

Viewing the Martian SunsetIf we’re unable, then, to visually capture the solar system in a single potent image, what can we do instead? One thingwe can do is focus on images like the Pathfinder sunset images, or better yet improved versions of these images thatwe’ll hopefully get from upcoming Mars missions.

[Image: Closeup view of yellowish sun on horizon] Because look what we have here. Right there in the center, we havethe Sun. The Sun retains its pride of place – the center of our attention. This is a Copernican Perspective, with the Sunas the basic frame of reference.

We know it’s a sunset, but we’re immediately aware of the strangeness of this particular sunset. The Sun is too small.And, assuming the image has not been overexposed [Image: Full horizon sunset, with paler sun] it’s too whitish, evenbluish. The hills on the horizon look familiar, but then we remember that those rocks are unlike anything we could findon Earth, and indeed are the product of an utterly different geological history. The pattern of fading light in the skylooks familiar, but something about the color and texture of the sky reminds us that we’re looking through an entirelydifferent type of atmosphere – thin, unbreathable carbon dioxide, often laden with dust. So the image is full of familiarelements, yet ones that are clearly out of kilter somehow. And it seems that this mixture of the utterly familiar and theutterly strange is one of the things that gives the image a particular power.

We have no doubt that we’re looking at a Martian landscape. Yet it becomes partially transformed into an Earthlylandscape, because we can’t help but freight the image with familiar connotations. Even if this is Mars, the horizonconjures up something similar to an Earthly horizon – namely a sense of boundedness, and simultaneously a sense ofthe beyond, of unknown territory that might be explored some other day. And even if this is the hostile physical worldof Mars, we tend to project onto the scene an atmosphere of stillness and quiet. In our mind’s eye it becomes a hushedlandscape, one imbued with peacefulness, perhaps even with a sense of the sacred.

We have no doubt that we’re looking at a scene of the future. After all, this is Mars, one of the prime destinations onthe space frontier, a new world waiting to be explored. But when we look at this image, we’re also looking at a veryancient scene, because we can’t help but invest it with certain age-old connotations. This is a very primitive tableau,one that Earthly hunter-gatherers have been gazing at for many thousands of generations. And it’s not only aboutstillness and the sense of the sacred. It’s also about fear: fear of the night, fear of the oncoming darkness and cold, andfear of animals in the night that can turn hunters into the hunted. Of course these chilly connotations quickly transform

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into warmer ones: a band of people gathered around a fire, finding safety in solidarity, surviving the night, coming tofeel they really belong in this place because they’ve learned to survive the night here.

High-Tech Hunter-GatherersIn thinking about what this image means, I want to make clear that I have not been trying to make a case for planetarychauvinism, i.e., the possibly sentimental belief that the surface of a planetary body is the only proper abode for humanlife. In opposition to planetary chauvinism, we have the views of people like Gerard K. O’Neill, who suggested that thesurface of a planetary body probably is not the best place for a high-tech civilization. My point is not to take sides insuch a debate.

Rather, the point is merely to analyze a Pathfinder image and make a case that it has a certain inherent power. It’s animage of Mars, but it also connotes the Earth; it’s an image of the future, but it also connotes the past. When we lookat it, we know we’re the inheritors of the Enlightenment, living in a time of exploding knowledge and possibility. Atthe same time, it makes us remember that for practically all of the past 150,000 years, we’ve been successful hunter-gatherers roaming the surface of Earth. It addresses us on many levels.

Such an image conceivably has the power to connect us to a mythic narrative. What sort of narrative? It’s a story aboutpeople who have been hunter-gatherers for almost their entire evolutionary history, but who have now very quicklydeveloped a high-tech civilization. Moreover, it seems inconceivable that they will abandon this high-tech civilization.Their technology has allowed them to begin – in very rudimentary ways – to explore the surface of other worlds. Themythic narrative, then, is the story of an emerging spacefaring civilization that takes with it ancestral memories thatreach far back into it’s origins on planet Earth. When we view the Martian sunset, therefore, we’re looking at an imagethat conjures up a mythic narrative of high-tech hunter-gatherers.

Mid-Presentation Break, for a Message from one of our Sponsors

It is more than merely fanciful to consider R. Buckminster Fuller one of the “sponsors” of the Mars Society. Fuller hasbeen described as “a romantic visionary who had few commercial instincts, little use for accepted wisdom, andextraordinary foresight.”5

One month ago – after several years of planning and negotiating – Fuller’s daughter and grandson decided to have hisenormous archives transferred from the Buckminster Fuller Institute in Santa Barbara, California, to Stanford University.Stanford hopes to enhance the recent signs of renewed interest in Fuller by organizing and cataloging the archives.

Fuller had a powerfully original mind, which among other things gave rise to 25 patents, 28 books, and 47 honorarydoctorates. Even those of us who can’t claim even a tiny fraction of his originality can still hope to imbibe some of hisspirit. Fuller believed that technology and inventiveness can solve our common problems, and he disliked the impedimentsto such problem-solving. Chief among those impediments, according to one commentator, were “tradition and culturallegacies, which thwarted the clear-eyed thinking needed to invent efficient ways of improving people’s lives.”6

No doubt many people would find this lack of respect for tradition and cultural legacies to be disturbing, perhaps evenarrogant. The wisdom of the ages may not always be that wise when applied to the present, but doesn’t culture andtradition at least connect us firmly with our past, giving us a sense of continuity and stability that enriches and deepensthe present? Irrespective of how Fuller might respond, consider this: The November 1997 Atlantic Monthly featured acover story by Freeman Dyson on colonizing the solar system. An editorial preface noted, “In a nation as self-consciously aware of potential as ours has been, contemplation of the future possesses some of the stabilizing functionof tradition.” If this is true – if thinking about the future can lend a stabilizing effect – than someone like Fuller mightin fact be showing a real respect for one of the underlying purposes of culture and tradition even as he rejects it whenit seems to hold us back.

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In any case, this brief digression on Buckminster Fuller, culture, and tradition serves as a good segue into the next partof this presentation. It will essentially consist of a catalog of some of the cultural resistances that impede more energeticspace exploration. It’s cast in the form of a message addressed to the future, to the first people to stand on Mars and seethe Martian sunset. Fuller, by the way, referred to people as “Earthians,” and sunsets as “sunclipses.” In histerminology, then, the rest of this presentation is a message addressed to the first Earthians to view a sunclipse from Mars.

A Message for the First to View the Martian Sunset LiveMany years before you even arrived on Mars, we first viewed the sunset you’re now looking at. We first saw it in 1997,back before the turn of the millennium. In reminding you of this, we are not trying to upstage you in any way. Thatwould be inconceivable anyway, because we saw only a crude facsimile of what you see now. We are merely trying todeepen our vicarious pleasure in your success by noting that we contributed to it, indirectly.

Even before the turn of the millennium, we had the technological sophistication to put humans on Mars. We had puthumans on the Moon in 1969, so we’d completed the basic training for a more ambitious voyage. But then,unaccountably, we grew sluggish and distracted. It was a time marked by certain entrenched cultural resistances, oftenon the part of influential opinion leaders. We had to overcome these cultural resistances. Before we could garner thecritical mass of public support needed for energetic space exploration, we had to confront and deal with the following:

We had to deal with the distracted.Distracted by what? By “down to Earth” matters of various types. And of course it’s always easy to find these. Evenat a time like the late 20th century, when in the economically developed world ordinary people were living like kingshad recently, and when approximately 2% of the people were producing all the food – even in such flush times peoplepersisted in thinking that life was tough and full of problems. And of course there were plenty of problems andchallenges: confronting perpetual evils like sickness, death, and crime; preventing warfare; spreading the technologicalwealth more uniformly; avoiding environmental degradation.

So we had to remind people, again and again, that serious space exploration required only a tiny fraction – perhaps amere 1 or 2 percent – of the funds they were willing to spend on other worthwhile projects. Moreover, we had to remindthem again and again that it’s precisely when a high-tech civilization pushes its limits with new challenges that therearise innovations that invigorate the entire society in unpredictable ways.

We also had to deal with those who were caught up in compelling scientific endeavors. In the late 20th century, twoareas were particularly absorbing: genetics and computers. Geneticists were exhilarated by progress in deciphering theDNA code, promising not only medical breakthroughs but also perhaps eventually the power to guide our ownevolution. Computer scientists steadily advanced electronic capabilities, producing drastic changes in the way peopleworked, communicated, and exchanged goods.

These were heady and exciting developments, but we also had to keep in mind the bigger picture. To the geneticist, wesaid: “By all means, keep your nose to the sequencing machines. But even before you finish analyzing the genome ofmany of the complex life forms on Earth, wouldn’t it be nice to have a sample from another world? Just think what youcould learn from one small strand of genetic material from a microbe found in a subsurface vent on Mars, or in an oceanbeneath the icy surface of Europa.” And to the computer scientist, we said: “Cyberspace is intriguing, but there’s verylittle ‘there’ there, compared to outer space. Besides, let’s assume you wire the entire world – realizing DesJardin’s‘noosphere’ of electronic interconnectedness. What then? Doesn’t this giant collective consciousness need some newinformation, some input from elsewhere? Today, information is streaming in to us steadily from other worlds in our solarsystem and beyond. To construct a “world-wide web” that focuses mostly on the information from just one of theseworlds seems awfully unambitious. Why, it even verges on cybersolipsism. You need facilities and terminals on Mars.”

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We had to deal with the deniersDeniers were those who thought and acted as if all possible sources of meaning, wonder, and value were tucked awaybeneath the atmosphere that envelops planet Earth. It may seem paradoxical that there could have been so many deniersin the late 20th century. After all, this was the era of the first great interplanetary probes, which unleashed a stream ofinformation and images that brought alive the details of the solar system for the first time in human history. How couldpeople have denied the power and impact of such compelling visual evidence?

It’s tempting to ascribe it to accidents of birth. Perhaps, as more and more people were raised in urban settings, fewerwere likely to have had a formative early experience of looking at a night sky and wondering what’s out there. Maybeit takes repetitive experience with the night sky to have it suddenly hit home that the stars really are very distant Suns,and that our presence on Earth – a spherical rock hurtling through black space – is really quite extraordinary.

Or maybe it necessarily takes some time for drastically new understandings to sink into our general consciousness. Thetwentieth century was an eye-opening time. In all the years leading up to it, we had no idea of the Big Bang – noconception of something as basic as an expanding universe. We knew very little about stellar evolution, hence didn’trealize that our star too will eventually turn into a Red Giant that will render Earth uninhabitable. Perhaps such basicfacts about the world take some time to really hit home (perhaps because when they do hit home they can at first bedisconcerting, disorienting even).

But in any case we had to convince the deniers. We had to keep showing them the images coming in from interplanetaryprobes: the bizarre Jovian moons, the storms visible on Saturn, the close-ups of Martian cliffs and sand dunes, thesnapshots of those strange little worlds we call asteroids. With deniers, these pictures were worth thousands of words.

We had to deal with earthbound environmentalistsSpace exploration and environmentalism are practically joined at the hip – the twin progeny of 20th centurytechnological advance. The Apollo image of the whole Earth helped launch the international environmental movement.Some have even suggested that space exploration – which in essence is about understanding Earth’s larger environment– should really be thought of as a species of environmentalism, as environmentalism on the grand scale.

But some environmentalists persisted in acting as if they thought Earth’s environment ended abruptly at the margins ofthat famous Apollo photograph. Part of their resistance to space exploration may have been a lingering suspicion oftechnology per se, not to mention an aversion to the noisy pyrotechnics of rocket launching. More importantly, theirelevation of the concept of wilderness led them to think that untouched parts of the solar system should remainuntouched, particularly by we who have environmentally sinned on Earth.

We had to try to convince these people that we can put footprints on other worlds and still retain a reasonablecautiousness about how we might affect potential ecosystems on those worlds. We had to stress the emerging views ofenvironmentalists such as William Cronon, who argued in 1995 that an unexamined idealization of wilderness was infact a threat to responsible environmentalism. We had to point out that space exploration in actual practice forcesenvironmental awareness of the most intense sort. After all, there can be no more dedicated recyclers than a band ofhumans trying to preserve limited resources in the unforgiving environment of a place like Mars.

We had to declare that we can hold certain things self-evident: that we live amidst a shooting gallery of crisscrossingasteroids and comets which occasionally dip into near-Earth space; that solar winds and flares can affect Earth’s upperatmosphere, climate, and even our communications infrastructure; that some of the meteorites which fall onto Earthfrom Mars conceivably contain fossils of microbial Martian life; that evidence is mounting that small shifts in the shapeof Earth’s orbit have produced dramatic climate changes on Earth; that the solar system itself may be moving toward aregion of interstellar gas and dust of a density that could eventually have far-reaching effects on the inner solar system;that other stars have their own planetary systems, ones which shed great comparative insight on our own system; finally,

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that we learned these things – many of which have crucial implications for understanding our Earthly ecosystem and itslong-term prospects – precisely because we made the effort to look and explore beyond the Earth..

In sum, we had to make the case that our true environment is the solar system. Earth is dynamically interrelated with awide variety of solar system physical processes, and the fate of our Earthly ecosystem is hitched to the fate of our starsystem. We had to make the case that environmentalists whose vision is confined within the frame of that Apollophotograph, no matter how sincere their expressed concern for Earth, remain intellectually confined to an earthboundenvironmentalism.

We had to deal with various strains of anti-Enlightenment thinkingThe Enlightenment first gathered momentum in Europe in the late 1700s, but by the turn of the millennium it hadbecome part of world culture. At the core of Enlightenment thinking is the idea that human powers of rationality,working through the empirical methods of science, can lead to material and even moral progress. However, even inthose societies that most energetically transformed Enlightenment ideas into material comfort and prosperity – in fact,especially in such societies – there remained some entrenched resistance to the ideas themselves.

Some of the resistance stemmed from superstition and wishful thinking. Astrological forecasts that link our daily affairswith certain stars, aliens who surreptitiously swoop down to abduct us and mate with us, gods who grant us health andwealth only if we perform the proper rituals: such notions are very responsive to our human need to feel significant.Science, with an outward-directed gaze that seems to find nothing but more questions, further immensities, and morecosmic indifference, simply can’t compete when it comes to delivering certain types of ego gratification. With thesuperstitious and the wishful thinkers, we had to try to find imaginative ways to convince them that the real mysteriesof the cosmos are at least as awe-inspiring as any imagined wonders. And we had to argue that it’s more than a littleego-gratifying to think of ourselves as creatures possessing astounding intelligence, remarkable inventiveness, andcourage enough to keep asking questions, unintimidated by apparent cosmic indifference.

Some of the anti-Enlightenment resistance stemmed from religious conviction. This was much less significant than ithad been in the past, when scientists had sometimes run up against the official disapproval of an established andinfluential Church. But still it persisted, for example in the tendency to see human attempts to explore and possibly evenalter other worlds as arrogant, as examples of human “hubris,” as attempts to “play God.” We had to try to convincesuch believers that our little forays into neighboring regions of our solar system – far from fostering arrogance – werein fact quite humbling. Moreover, by helping us really understand our homeworld, they aligned squarely with traditionalnotions of stewardship of our world.

Some of the most perplexing anti-Enlightenment resistance came from professors and other influential thinkers, peoplewhom one might think would be the most ardent proponents of the Enlightenment. Many of these people identified with“postmodernism,” which included at its core a deep suspicion of rationalism, science, progress, and other Enlightenmentarticles of faith. Much of their suspicion was a type of post-traumatic stress – a lingering shock at the realization thatallegedly enlightened civilizations had produced the horrors of the World Wars, the Holocaust, the Bomb, and a host ofenvironmental problems. We had to try to convince these people that nevertheless we seem to have muddled through,and that our high-technology civilization may not self-destruct after all. The poet Randall Jarrell, knocking theoptimism of the Enlightenment, wrote, “Most of us know, now, that Rousseau was wrong: that man, when you knockhis chains off, sets up the death camps.” To those who shared Jarrell’s deep pessimism, we had to say, “Look at the worldwith both eyes open. When our chains are knocked off, we also invent antibiotics, save millions of infants from earlydeath, interconnect the world, and begin to reach out to other worlds.”

Part of the postmodernist program was an insistence that science and technology is a complicated cultural system.According to Wolf Lepenies, for example, science should not be seen as faithfully reflecting reality: “What it is, rather,is a cultural system, and it exhibits to us an alienated interest-determined image of reality specific to a definite time andplace.”7 To those who held such views, we had to lay down a postmodernist challenge: “Mr. Lepenies, let’s put aside

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unproductive debates about reality. Let’s speak now about a definite time and place. The time is 1999 (by one arbitrarycalendar system), and the place is planet Earth. At this time and place, a remarkable cultural system has recentlyemerged, and moreover has spread – albeit not yet uniformly – all around the planetary surface. Let’s call it theTransportational Culture. You have some familiarity with it already, because when you travel to academic conferencesyou rely on its cultural artifacts – e.g., the airplane, the train, the bus, and the automobile. You are also aware that theTransportational Culture makes a habit of transporting voices, images, and personalities apart from bodies – via thecultural artifacts called radios, telephones, televisions, computers, and satellites. Well, Mr. Lepenies, some members ofthe Transportational Culture think that one of our interests lies in transporting ourselves to other specific places, i.e., tonon-Earth worlds. We have already begun to do so – by transporting robotic proxies that are bringing back images andinformation from other places. We believe that experiencing such places gives us a deeper experience of the Other –not to mention a more literal and more useful kind of alienation – than can be found anywhere within theTransportational Culture’s home turf, i.e., planet Earth. Will you come with us? Will you let us transport you, at leastin your imagination?”

We had to deal with biological pessimismEven some of our greatest pro-Enlightenment champions were prone to biological pessimism. Consider Edward O.Wilson, whose influential 1998 book Consilience was an unapologetic celebration of an updated Enlightenment vision.Near the end of the book, Wilson proposed two competing self-images. Homo proteus, the “shape-changer,” has thefollowing characteristics: “Indeterminately flexible, with vast potential. Wired and information-driven. Can travel almostanywhere, adapt to any environment . . . Thinking about the colonization of space . . .” The contrasting image is that ofHomo sapiens, who is, “Basically a primate species in body and emotional repertory . . . Runs on millions of coordinateddelicate biochemical reactions. Easily shut down by trace toxins and transit of pea-sized projectiles . . . Dependent inbody and mind on other earthbound organisms. Colonization of space impossible without massive supply lines . . .”

Wilson thought his Homo sapiens – a biologically constrained primate – was the more accurate human self-image. Andhe went on to discuss the 1991 Biosphere 2 experiment as having shown us the vulnerability of our species. He quotedthe conclusions of the senior biologists who reviewed the Biosphere 2 data: “No one yet knows how to engineer systemsthat provide humans with the life-supporting services that natural ecosystems produce for free . . . despite its mysteriesand hazards, Earth remains the only known home that can sustain life.”

We were profoundly grateful to Wilson for his celebration of Enlightenment values at a time when they were somewhatunfashionable, at least in the academy. Nevertheless, we had to counter his biological pessimism. We had to insist that theoperative word in “No one yet knows how to engineer systems . . .” is yet. We had to argue that Biosphere 2 proved the needfor Biospheres 3, 4, and 5, and moreover for more generous funding for research into regenerative life support systems andenvironmental monitoring and control. We had to point out the growing interest in what was initially called “astrobiology,”but which really was just biology from a broader purview. We had to read and promote serious scientific explorations ofastrobiology, e.g., books like Robert Shapiro’s Planetary Dreams, Paul Davies’ The Fifth Miracle, and Michael Lemonick’sOther Worlds. And we had to repeat again and again all the arguments against a strictly earthbound environmentalism.

Finally, we had to suggest that with all due respect to Wilson’s competing self-images, for continuation of the speciesthe best choice is a hardy Homo sapiens / Homo proteus “hybrid” with the following characteristics:

“Basically a primate species in body and emotional repertory, but with astounding powers of imagination and intellect.Runs on millions of coordinated delicate biochemical reactions, yet is able to understand and deliberately affect thosereactions to a remarkable degree. Knows that colonization of space is presently impossible without massive supplylines. Also knows that systematic and persistent exploration will make the supply lines progressively less massive.Insists on spending at least 3% of overall budget on such exploration. Irrepressibly curious about other worlds, and thepossibility of life elsewhere in the universe. Becoming increasingly aware of possibility of another Earth-asteroidcollision, and resulting environmental destruction. Gradually coming to conclusion that for wise stewardship ofSpaceship Earth, should start creating Spaceship Mars.”

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References1. But note that leaf-cutting ants had learned to tend their fungus farms 50,000,000 years earlier.2. Frank White, interview in Ad Astra magazine (March/April 1999), p.46.

3. Frank White, The Overview Effect: Space Exploration and Human Evolution—2nd Ed. (American Institute of Aeronautics and Astronautics,1998), p. 12.

4. Joseph Campbell, The Mythic Image (Bollingen Series C, Princeton University Press, 1974).5. “The Face of the Future is a Thing of the Past,” feature article by James Sterngold in New York Times, Saturday July 17, 1999 (Arts & Ideas, B7).6. Ibid.7. C.P. Snow, The Two Cultures (Cambridge University Press, 1993), Introduction by Stefan Collini, p.l.

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A Proposed Design for Wastewater Treatment and Recycling at the FlashlineMars Arctic Research Station Utilizing Living Machine Technology

D. Blersch; E. Biermann; D. Calahan; J. Ives-Halperin; M. Jacobson; P. Kangas[2000]

AbstractThis paper presents a second-generation wastewater treatment design for the FMARS habitat. The system discussed isa modified recirculating living machine in which recycling and recovery of water is accomplished. The primary purposeof the design is to treat the black and gray water waste streams from the FMARS habitat. However, biomass is alsoproduced by the system that shows potential for the provision of other life support functions. The system is designedto recycle for reuse all wash water and toilet waste from the FMARS habitat. Options are presented for both fullrecycling to potable use and for partial recycling to non-potable use. The design comprises a sequential system oftreatment unit processes, beginning with an anaerobic digester, followed by a trickling filter, constructed wetland, andthen a disinfection and purification step. It is intended that the system will attach via appropriate plumbing to theexterior of the FMARS structure; hence the system is designed to be modular and transportable. The system could belocated in either a greenhouse or a closed structure with artificial lighting, depending upon energy budget considerations.A scaled design is presented as a possible floor plan with quantitative sizing of unit process components based on ahypothetical crew number and loading rate. While the focus of the analysis is on a design for wastewater treatment andreuse, discussion is provided on ways of expanding the system to provide additional life support functions desirable foractual Mars habitation.

IntroductionThe Mars Society’s Flashline Mars Arctic Research Station (FMARS) was designed, fabricated, and constructed overthe course of 10 months from August 1999 to June 2000. Sited in the NASA research site in Haughton Crater in DevonIsland of Northern Canada, the FMARS serves as a living research laboratory for investigating technological and humanfactor considerations for preparing for a manned mission to Mars. The austere landscape and severe Arctic conditionsmake Haughton crater one of the best Martian analogs on Earth, and thus the FMARS is poised to be a primarycontributor of knowledge to the ever-progressing effort of mission planning for a manned Mars mission.

Despite the intention of being an analog Mars mission, the remoteness of the FMARS facility, combined with theregulatory climate that surrounds its location, contribute to the short-term logistical difficulties of resupply and wastemanagement. Haughton Crater on Devon Island is quite remote, located at about 75 degrees north latitude in Canada’sNunuvut territory (Mars Society 2000a) and hundreds of miles away from the nearest village (Resolute on CornwallisIsland). Resupply of provisions is performed by way of airlift, a difficult operation even in the best of conditions. Also,Canadian environmental regulations recognize the fragility of the local environment on Devon Island and thereforeforbid the discharge of untreated wastewater. Past research expeditions to Haughton Crater have managed waste bysealing it in drums and periodically airlifting it out, a difficult and costly operation. Because of the potential high-useof the FMARS in future research seasons, it is desirable that the FMARS have a system to recycle some or all of thewastewater it produces that in some way is analogous to a system that might accompany a manned mission to Mars.

Project HistoryThe Maryland subgroup of the Mars Society’s Life Support Technical Task Force has been looking at various ways toaddress the issue of waste management and recycling at the FMARS facility. The subgroup coalesced as part of thelarger task force originally formed via electronic communication in December of 1999. With over 32 members fromvarious technical backgrounds and geographical locations, the technical task force organized in spring of 2000 toaddress issues of life support design for the FMARS facility. As its design guidance, the Technical task force adoptedfor itself the following mission statement:

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D. Blersch, E. Biermann, D. Calahan, J. Ives-Halperin, M. Jacobson, P. Kangas; Mars Society Life Support Technical Task Force, MarylandSubgroup; University of Maryland, College Park, MD; Web site: http://home.marssociety.org/tech/htm

“The Life Support Project of the Technical Task Force will design a wastewater processing system for the FMARSstation, capable of being deployed in summer of 2001. It will be an ecologically engineered sequence of biological unitprocesses, with the capability of adding further functions in subsequent years.” (Mars Society 2000b)

With this as the overarching guidance, considerable electronic communication and idea sharing ensued. A core set ofbrainstorming topics arose that stand as valid considerations in designing and constructing the FMARS waste treatmentsystem. A selection of these topics is presented in Table 1. Many topics are important design considerations andoperational constraints that arise from the biological nature of the proposed system. It is assumed that these topics willbe addressed in future design iterations. Other topics arise from concerns over the physical location of the FMARSstation and the severity of the physical environment as well as the regulatory environment. Design iterations will haveto take these considerations into account as well. With these in mind, the task force chose to lay out a conceptual designthat could work for the FMARS facility, pursuing solutions to detailed design and regulatory challenges only aftersanctioning of the project by the larger Mars Society organization.

Table 1. Selection of Technical Task Force e-mail / brainstorming topics for possibleconsideration in the detailed design of the FMARS wastewater treatment system.

Design ApproachPhilosophy:The design philosophy pursued by the Maryland subgroup of the technical task force was within the context of existinglife support systems for space, past or present, and proposed systems. It was recognized that life support systems forany mission could be described by its placement on at least three categorical gradients (Figure 1). The first gradientdescribes the degree to which a system is regenerative versus non-regenerative – that is, the degree to which the cyclesfor life support necessities of air, water, and food are closed (Eckart 1996). A life support system that relies upon storageof food, water, and oxygen, and stores waste products as they are produced for transport or disposal is generally non-regenerative, whereas a system that recycles air and water and produces food is regenerative. The second gradientdescribes the degree to which a system employs biological versus physical / chemical operations for various life supportprocesses. Physical / chemical life support systems have a long history of engineering design and implementation andhave proved reliable in many space mission applications; however, it is generally agreed upon that long-term missionsrequire some degree of biological components besides the human occupants, especially for the function of foodproduction (Beyers and Odum 1993). The third gradient describes the degree to which a system relies upon integratedsubsystems to perform multiple functions versus separate systems to perform separate functions. For example, a lifesupport system that incorporates photosynthetic vascular plants is inherently multifunctional, as it addresses bothatmosphere management (oxygen production and carbon dioxide consumption through photosynthesis) and watermanagement (potable water production through transpiration).

Past and present existing and conceptual systems might be categorized by each of these three gradients. Life supportsystems for the Apollo space capsules recycled some air and water, but relied upon stored foods: it thus can be

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A Proposed Design for Wastewater Treatment and Recycling at the Flashline Mars Arctic Research Station Utilizing Living Machine Technology

categorized as moderately regenerative, completely physical / chemical, and comprising processes with separatefunctionality. Odum (1963) proposal for two acres of enclosed complex ecosystem per person to supply all the humanlife support needs, powered by nothing but the sun, serves as an extreme on all gradients: completely biological (exceptfor its container), completely regenerative, and completely integrated functionality. It was recognized that the currentlife support “system” employed by the FMARS stands at the opposite extreme on all gradients; relying upon airliftingin all food and water, airlifting out all solid and liquid waste, and on the in situ atmosphere for respiration needs, thecurrent FMARS life support is completely non-regenerative, completely physical processes, and completely separatefunctionality. Focusing on the waste treatment needs of the FMARS facility, the technical task force chose to pursue adesign to maximize the regenerative, biological, and multifunctional nature of the system. However, recognizing theconstraints imposed by the seasonally harsh environment of the FMARS location and by possible budgetaryconsiderations, the task force strove to produce a design that was comparable to current state of the art in regenerativelife support technology: moderately biological, moderately regenerative, and moderately multifunctional.

To accomplish this, the task force chose to design a wastetreatment system using concepts of ecologicalengineering (Mitsch 1993; 1996). An ecologicallyengineered system is one that is based upon complexcommunities of micro- and macro- organisms. It isessentially a controlled ecosystem in which energy inputsare kept within bounds to maximize certain functions ofthe ecosystem. Biological by definition, ecologicallyengineered systems are inherently multifunctional, as thesystem complexity provides multiple pathways forresource processing and recovery. Ecologicallyengineered systems are also inherently stable as a system,with the complexity providing internal homeostaticregulation that dampens out the system’s responses todynamic perturbations. Some ecologically engineeredsystems such as algal turf scrubbers (Adey et al. 1993;

Craggs et al. 1996) and constructed wetland system (Reed et al. 1995; Kadlec and Knight 1996) have been welldeveloped and studied for application in wastewater treatment. In previous papers, members of the technical task forceanalyzed various ecologically engineered systems for wastewater treatment and showed that they could be reasonablyscaled for use in a Mars mission life-support scenario (Blersch, et al. 1999; 2000). Pursuing an ecologically engineereddesign for the purpose of wastewater treatment at the FMARS facility provides a platform with inherentmultifunctionality which might be capitalized upon in the future for other life support functions (i.e., food production,atmosphere revitalization).

Model systemsThe technical task force decided to base its design for the FMARS system upon existing systems for small-scalemunicipal wastewater treatment, and modify as necessary to conform to limitations imposed by the unique situation ofthe FMARS facility. While other candidate systems were investigated (Parker et al. 2000; Kok 1999), the Marylandsubgroup decided to use as its model the Second Nature® Wastewater Treatment System, designed by Natureworks inVirginia (Ives Halperin and Kangas, 2000). The Second Nature system was designed and installed for the MidlandMasonic chapter in rural Midland, VA, approximately 50 miles outside of Washington, DC. Original plans for thechapter’s recently completed community lodge facility called for a standard residential septic tank / leach field system,but regulatory restrictions imposed by the State of Virginia Department of the Environment prevented this because oflow soil permeability and proximity to the lodge wellhead. Nature Works, Inc., of Alexandria, Virginia, hired by thelodge to investigate alternatives, designed and built the Second Nature waste treatment system, a closed-loop wastewatertreatment system that recycles black and gray water back to the lodge toilets. The Second Nature® system is effectivelya modified “living machine” (Todd and Josephson 1996; Todd 1991), a series of ecologically-based unit processes that

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Figure 1: Categorical gradients to be considered in the designof the total or components of a mission life support system.

rely on natural processes of aquatic and wetland ecosystems to accomplish secondary and tertiary treatment of the septictank effluent (Figure 2). The entire biological treatment process is contained within a small greenhouse (Figure 3) andeffectively treats household sewage to bring it within the permitted standards of 10:10:10 mg/L of biochemical oxygendemand: total suspended solids: total nitrogen (BOD:TSS:TN). Effluent from the system is held in a clean water storagetank for reuse on demand in the lodge toilets, following carbon deodorizing and ultraviolet disinfection. Discharge toan underground rock-sand infiltration bed occurs only in times of high flow.

Figure 2. Second Nature wastewater treatment system flow diagram that served as a model forthe design of the FMARS wastewater treatment system (from Ives-Halperin and Kangas 2000).

Figure 3. Greenhouse containing the Second Nature™ biological wastewatertreatment system designed and constructed by Natureworks in Midland, VA.

Design ApproachWaste Stream Characterization:After selection and study of a model for the design was complete, scaling a wastewater treatment system adequate forthe FMARS facility required characterization of the hypothetical habitat waste load. Because of data on the wasteproduced at the FMARS facility had not yet been compiled, the task force made assumptions about the volume andconcentration of wastewater generated from the FMARS station. Hall and Brewer (1987) present volumes ofwastewater produced for two mission scenarios: a mission relying entirely upon food stores, and a mission that includes

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food production. Assuming that the FMARS missions will replicate food production mission scenarios, the assumedvolume of wastewater generated is 67.3 L (17.8 gal.) per man per day (Hall and Brewer 1987). Assuming a six-mancrew for the FMARS facility, and multiplying by a safety factor of 1.5 yields a wastewater flow rate of 625 L/day.

To characterize the constituent makeup of the wastewater, it was assumed that the wastewater to be treated at the FMARSfacility includes all but laboratory wastewater (it was assumed that laboratory waste is generally considered hazardous andtherefore poses a special disposal situation not to be immediately addressed by the technical task force). Thus wastewaterwould include most constituents found in standard household waste: human metabolic solid and liquid wastes, foodpreparation water and waste solids, wash water and waste solids (including mild detergents), and inedible plant biomass.Metcalf and Eddy (1991) give unit waste loading factors for various component constituents for standard householdwastewater, in units of mass produced per man per day. Assuming conservatively that wastewater generated at the FMARSis generally more concentrated than average household wastewater, the upper bound of the range given for each of thewaste loading factors by Metcalf and Eddy (1991) was used for subsequent design calculations. Multiplying these waste-loading factors by the assumed daily flow rate yields average constituent concentrations, shown in Table 2. Additionally,target levels for the effluent of the treatment process are listed, assumed from information given by Eckart (1996).

Table 2. Assumed waste stream characterization for the FMARS design

Description of proposed systemWith this information for the waste load characterization, calculations were performed to scale the selected unitprocesses for the system. A schematic flow diagram of the proposed system is shown in Figure 4.

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Figure 4. Proposed design concept for the FMARS wastewater treatment system (Mars Society 2000b)

A description of the system is as follows (Mars Society 2000b). All water and toilet waste generated within the F-MARS habitat is collected in the anaerobic digester for treatment of the complex organics. Anaerobic bacteriasignificantly reduce the biochemical oxygen demand (BOD), producing carbon dioxide and methane. Control andstream separation may be necessary for most laboratory and some kitchen waste, in which case the digester might havemultiple chambers to deal with complex waste streams. The anaerobic digester will be airtight and have a flexiblebladder for its top to collect methane for possible refinement and use within the habitat. Additionally, most solids settleout here. Solids production will be low with a crew of only six, and might be minimized even further by maintainingthe anaerobic digester at an optimum temperature of 35°C. However, periodic disposal of the solids (i.e., once per year)might be necessary. For the design calculations, a standard hydraulic residence time of 48 hours was assumed, andstandard sizing equations based upon desired BOD reduction were used (Metcalf and Eddy 1991).

Water exiting the anaerobic tank is pumped to the top of the trickling filter via an airlift pump in a screened filter vault.An airlift pump is a simple way to move fluid compared to most other pumps, as it requires little power and lowmaintenance. Airlifted effluent trickles over the filter media and is thereby aerated. Filter media is typically alightweight corrugated plastic construction with a high surface area per volume. The aerobic microorganisms thatcolonize the media utilize the energy and organic compounds that remain in the water, quickly reducing BOD and COD(Metcalf and Eddy 1991). Additionally, the aerobic environment induces nitrification by the attached bacteria,converting ammonia nitrogen to nitrate nitrogen. The trickling filter might be designed as a waterfall for aestheticpurposes and thus contribute to the “livability” of the habitat. The effluent leaving this filter is relatively clean with asignificant amount of the nitrogen and carbon compounds removed. Effluent from the trickling filter flows via gravityinto the next unit process. To size the trickling filter, standard sizing equations were used assuming a desired BODremoval efficiency of 80% and an ambient temperature of 20°C (Metcalf and Eddy 1991).

Effluent from the trickling filter flows into the constructed wetlands for nutrient removal and final polishing. Wetlandsfor waste treatment are constructed with complex, stable communities of emergent plants. The plant roots and rocksubstrate of the constructed wetlands provides a large surface area for attached biofilm growth. Many wetland plantshave adaptations to transport oxygen to their roots, thus creating a complex subsurface environment of mixed zones ofaerobic and anaerobic conditions. This environment supports both nitrifying and denitrifying microorganisms thatconvert organic nitrogen, ammonia, and nitrate to plant and microbial biomass and nitrogen gas (Kadlec and Knight1996). The effluent from the wetland will be recycled back through the trickling filter two times per volume flow ratefrom the anaerobic digester. This recycle flow provides another nitrification-denitrification cycle, further reducing thetotal nitrogen coming through the system and allowing the wetland size to be smaller than a system with no recycle.The wetland also acts as a filter for any suspended solids that have made it through the trickling filter. To size thewetland unit process, equations were used with a desired TKN removal to 10.5 mg/L, assuming a well-developedsubsurface root zone and an ambient temperature of 20°C (Reed et al. 1995).

Following the wetland step, the water ends up in clean water storage, having been treated to advanced standards.Following disinfection by ozone or ultra-violet light is acceptable for recycling for non-potable reuse applications in andaround the habitat. These applications might include showers, laboratory wash water, plant irrigation, laundry, and toiletflushes. Water suitable for drinking would require additional sterilization and filtration and will not be addressed in theinitial system installation. Water for irrigation of agricultural or ornamental plants (as part of an atmospheremanagement system) would probably not need to run through an advanced sterilization cycle, and a single-timeozonation would be adequate.

Design AnalysisComparison with model system:It is helpful for visualization and physical layout purposes to compare the scaled unit processes of the proposed FMARSsystem with those of the existing model system. Table 3 summarizes the scaled parameters for the proposed FMARSsystem with parallel parameters measured from the Second Nature system. The comparison is not entirely a parallelone: the Second Nature system is designed for a much larger loading rate and thus has extra volume capacitance. The

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numbers presented for the FMARS design represent the smallest possible complex biological wastewater treatmentsystem given the assumptions and safety factors described above.

Table 3. Comparison of proposed FMARS wastewater treatment system with existing system

With this scaling information, it is possible to begin conceptualizing possible layout arrangements for the unit processesproposed here. One possible layout is presented in Figure 4. This layout assumes installation of the system in a greenhouse,double paned to provide maximum insulation from the outside arctic environment. The anaerobic tank is constructed intothe structural greenhouse wall adjacent to the FMARS habitat, providing the tank with the best possible thermal insulationbetween the two structures. A distribution manifold following the trickling filter ensures a steady flow rate and constantdelivery of water to all parts of the treatment wetland. A recycle line following the wetland unit process recycles up to two-thirds of the flow back to the start of the wetland step to ensure adequate nutrient removal. Flow for nearly the entire system

is gravity feed; a 1½hp pump providespressure head fordelivery of waterwithin the FMARS,and a small, lowpower, maintenancefree airlift pumprecirculates water tothe storage tank via adisinfection step.Note that this sche-matic assumes recycleof water to non-potable applications.Potable use ofrecycled waterrequires additionaldisinfection, filtering,and polishing stepsthat can be pursued infuture design iter-ations if interestwarrants.

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Figure 5. Design schematic of proposedbiological wastewater treatment system

attached to the FMARS habitat.

ConclusionsDesign of a biologically based wastewater treatment system for reuse and recycling of water is difficult even fortemperate climates, so the Arctic environment of the FMARS habitat poses unique challenges to the design process.Table 4 is a summary of many of the major design topics and steps that must be systematically addressed to bring theconceptual design proposed here to the point of construction and implementation. One of the major analyses yet to beperformed is a detailed power consumption and cost analysis for the system. Design for harsh Arctic conditionsundoubtedly increases the expected cost of the system - perhaps prohibitively beyond what is desirable by the MarsSociety. However, biological processes are easily adaptable to warmer climates with a steady annual light regime: theMars Society’s proposal for other Mars habitat analogs installed in more temperate environments would provideexcellent opportunity to test ecologically-designed life support technologies within analog mission scenarios.

Table 4. Design topics, analyses, and steps required prior to implementationof the FMARS wastewater treatment system concept proposed here

An unavoidable drawback to a system of this design – and often of certain ecologically engineered systems – is the largearea requirement to maximize photosynthetic unit processes. This is generally unavoidable if higher plants are desiredfor use in the life support system. However, pursing a treatment wetland concept in this design offers distinctadvantages. The wetland might be constructed using in situ rock and regolith for its growth substrate, essentiallyproviding a major contribution to the water treatment process with little or no investment in transportation costs. Thewetland area might also be expanded and employed for production of agriculturally valuable crops, adding to themultifunctional value of the system. Additionally, with its complex community of emergent plants, a wetland area hasan aesthetic appeal that can contribute to crew morale. Expansion of this system’s size and complexity approaches thescale of biospheres that might be desirable for long-term human habitation on Mars.

While the design presented here is preliminary and conceptual, the examples provided by existing systems show theadvantages of the ecological engineering approach to wastewater treatment design for the FMARS mission. Theecological communities provide complex stable systems with considerable biological diversity and multiple pathwaysfor nutrient sequestering and removal. The complex biological structure is also inherently multifunctional: in additionto cleansing wastewater for reuse, the system proposed here has the potential for food production scenarios whileproviding an aesthetically-pleasing environment. Additionally, this multifunctionality might be capitalized upon in thefuture through expansion into larger food-production operations or through integration of photosynthetic unit processes

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designed for atmospheric management. In this way, the system proposed here stands as a basic platform upon whichfuture FMARS missions might study and explore various scenarios for life support.

References1. Adey, W., Luckett, C., Jensen, K. 1993. Phosphorus removal from natural waters using controlled algal production. Restoration Ecology 1: 29-39.2. Beyers, R.J., Odum, H.T. 1993. Ecological Microcosms. Springer Verlag, New York.3. Blersch, D., Biermann, E., Kangas, P. 2000. Preliminary design considerations on biological treatment alternatives for a simulated Mars base

wastewater treatment system. SAE Technical Paper Series 2000-01-2467, Society of Automotive Engineers, Warrendale, PA.4. Blersch, D., Biermann, E., Kangas, P. In press. Preliminary design considerations for the M.A.R.S. wastewater treatment system: Physico-

chemical or living machine? Proceedings of the Second International Convention of the Mars Society, August 12-15, 1999 University ofColorado, Boulder.

5. Craggs, R.J., Adey, W.H., Jessup, B.K., Oswald, W.J. 1996. A controlled stream mesocosm for tertiary treatment of sewage. EcologicalEngineering 6: 149-169.

6. Eckart, P. 1996. Spaceflight Life Support and Biospherics. Torrance, CA: Microcosm Press.7. Hall, J.B., Brewer, D.A. 1986. Supercritical water oxidation: concept analysis for evolutionary space station application. In: Aerospace

Environmental Systems: Proceedings of the Sixteenth ICES Conference P-177. Warrendale, PA: Society of Automotive Engineers.8. Ives Halperin, J., Kangas, P.C. 2000. Design analysis of a recirculating living machine for domestic wastewater treatment. 7th International

Conference on Wetland Systems for Water Pollution Control. International Water Association, Orlando, FL. pp. 547-555.9. Kadlec, R.H., Knight, R.L. 1996. Treatment Wetlands. CRC Press, Boca Raton.10. Kok, T. 1999. Biostar-A: A first year report: Living with a home-scale biological life support system. Proceedings: 1998 Third International

Conference on Life Support and Biosphere Science, Orlando, Florida.11. Mars Society. 200a. Flashline Mars Arctic Research Station (FMARS): Project Background. Internet publication:

http://arctic.marssociety.org/about/background.html.12. Mars Society. 2000b. Technical Task Force Life Support Project, FMARS Wastewater Treatment System Conceptual Design version 1.0.

Internet publication: http://home.marssociety.org/tech/life_support/htm/design/design1.htm.13. Metcalf and Eddy, Inc. 1991. Wastewater Engineering: Treatment Disposal Reuse. New York: McGraw-Hill.14. Mitsch, W.J. 1996. Ecological engineering: A new paradigm for engineers and ecologists. In: Engineering Within Ecological Constraints.

Schulze, P.C. (ed.). National Academy Press, Washington, D.C. 111-128.15. Mitsch, W.J. 1993. Ecological engineering – A cooperative role with the planetary life-support systems. Environmental Science & Technology

27: 438-445.16. Odum, H.T. 1963. Limits of remote ecosystems containing man. Am. Biol. Teach. 25: 429-43.17. Parker, L., Sanders, T., Edeen, M. 2000. A water reuse system for Pike’s Peak, Colorado. Life Support and Biosphere Science vol.7 no. 1. 4th

International Conference on Life Support and Biosphere Science, Baltimore, Maryland.18. Reed, S.C., Crites, R.W., Middlebrooks, E.J. 1995. Natural Systems for Waste Management and Treatment. New York: McGraw-Hill.19. Todd, J. 1991. Ecological engineering, living machines and the visionary landscape. pp. 335-343. In: Ecological Engineering for Wastewater

Treatment. C. Etnier and B. Guterstam (eds.). BokSkogen, Stensund Folk College, Trosh, Sweden.20. Todd, J., Josephson, B. 1996. The design of living technologies for waste treatment. Ecological Engineering 6: 109-136.

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Applications of Wearable Computing to Exploration in Extreme Environments

Christopher E. Carr; Dava J. Newman[2000]

AbstractWearable computing technologies have the potential to enhance human exploration in extreme environments by servingas multifunctional tools, including serving as cognitive aids, communications tools, research assistants, and real-timehealth and performance monitors. Future planetary explorers may also use wearable systems to provide “just in time”training or to serve as an entertainment device or virtual abode of privacy while living in cramped quarters. This paperdiscusses potential uses of wearable computing technologies for planetary exploration on Earth and Mars, as well aspotential uses in weightlessness. A wearable computer-based biomedical monitoring and cognitive aid experiment,tested via ground studies and in simulated weightlessness on the NASA KC-135 aircraft, demonstrates some potentialuses for wearable computing by astronauts, and indicates necessary areas of improvement for wearable computingtechnologies. Lessons learned and future opportunities are also briefly discussed.

IntroductionDuring exploration in extreme environments, lowered performance can have ultimate consequences such as missionfailure or loss of life. Lack of awareness or knowledge about the environment can lead to disaster. Minor health problemscan become seriously debilitating. Cognition can be impaired due to environmental conditions or health. Groupcommunication and coordination may suffer. Task proficiency may become degraded due to lack of practice. Skillsoutside of previous training may be needed. Finally, psychological needs may go unmet – contact with family or friendsmay be impossible, creative or entertainment outlets may not be available, and privacy may be difficult or impossible.

Many of these problems can be mitigated through timely access to information, including information relating to thestate of the explorer. Wearable computers have the potential to mitigate some of these problems by serving asmultifunctional tools that function as both monitoring devices and information delivery devices. Wearable computingtechnologies can enhance self-sufficiency, autonomy, and human / machine teaming by enhancing local humanperformance and mediating outside interactions.

BackgroundA wearable computer can be roughly characterized as a computing device that is portable while operational, capable ofhands free use, able to sense characteristics of its environment, is “always on,” and is capable of augmenting humancapabilities (Rhodes, 1997).

In a more abstract fashion, a wearable computer can be thought of as a human-centric device that performs informationprocessing for or in cooperation with a user. Using this definition, one might consider as relevant the first mention ofthe eyeglasses in 1268 or the following expression of Robert Cooke in 1665 (Wearables, 2000):

The next care to be taken, in respect of the Senses, is a supplying of their infirmities with Instruments,and as it were, the adding of artificial Organs to the natural . . . and as Glasses have highly promotedour seeing, so ‘tis not improbable, but that there may be found many mechanical inventions to improveour other senses of hearing, smelling, tasting, and touching.

Other important events in the history of wearable computing include (adapted from (Wearables, 2000)):

• Invention of the pocket watch by John Harrison (1762).• Development of the first wrist watch by Louis Cartier (1907).• Proposal of the idea of augmented memory by Vannevar Bush (1945).

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Christopher E. Carr & Dava J. Newman; Department of Aeronautics and Astronautics, Massachusetts Institute of Technology; Emails:[email protected]; [email protected]

• First stereoscopic head-mounted display (HMD) produced (1960).• First wearable computer (built to predict results of a spinning roulette wheel) built by Thorp and Shannon (1966)• First computer-based HMD developed by Sutherland (1966).• S. Mann develops backpack-mounted computer for photography (1981).• Student Electronic Notebook demonstrated by G. Maguire and J. Ioannidis (1990).• T. Starner starts constantly wearing his computer (1993).• Rapid advances in wearables research and technology; commercially produced wearable computers; strong interest

in military and aerospace markets (1994-2000).

Wearables and ExplorationWearable computers can enhance human exploration in extreme environments by serving as multifunctional tools. A wearablecomputer may function as an information capture tool, a health and performance monitor, a cognitive aid, a communicationand coordination tool, a tool for education, training, or retraining, or as a tool to provide psychological support.

A wearable computer can serve as an information capture tool via automated information capture or by directed (user-initiated) information capture. The wearable computer may act as a recorder, binding context to information (such asposition or time information, or other relevant data related to user activity) so the user can focus on the task at hand.The wearable computer may also have the capability to share that information over a network to other users or machines.Directed information capture might be enabled using multiple interfaces such as haptic input devices, gestures, voicecommands, or direct manipulation interfaces (i.e., for visual input, a camera is a direct manipulation interface).Recording of audio, images, video, or text might be appropriate for a large number of applications.

Wearable computers can also serve as biomedical monitors. A wearable computer may non-invasively monitor a seriesof physiological parameters such as heart rate (or a full electrocardiogram), blood oxygen saturation, blood sugar, bloodnitrogen, respiration rate, or walking gait. The wearable computer might contain a physiological model, potentiallytailored to the individual user, and might be able to provide real time physiological feedback or intervention or suggesta remote consultation with medical personnel. Measurements could be made during normal daily activities of anexplorer in an attempt to reduce the number of perceived extraneous medical tests required in some environments (suchas during long-duration space flight). In addition, wearable computers might provide environmental safety assuranceby using wearable sensors to monitor atmospheric gasses such as O2, CO2, CO, NO, or potential airborne toxicchemicals. Temperature or pressure monitoring might also be appropriate in some environments. Biomedicalmonitoring using wearable computers raises important privacy issues that must be considered in conjunction with thetechnical advantages that might be achieved by such monitoring.

Wearable computers might serve as cognitive aids by functioning as information gatherers and presenters, providingusers with procedural checklists or technical references (“interactive electronic technical manuals”), or functioning as“expert systems” for troubleshooting of equipment or other problems. A wearable computer might also serve as a signalprocessing system with data visualization or enhancement capabilities. Past wearable computing systems have beenused as visual information processing platforms with features such as spatial and tonal enhancement (Mann, 1998).These cognitive aids might function as decision aids or planning tools, and may have personalized interfaces tailored toan individual.

Using a wearable computer as a mediation tool might enhance communication and coordination between users ormachines. The wearable computer might function as an attention access regulator, or as an interface to experiments orequipment (thereby reducing the need for experiment-specific or equipment-specific displays except as desired forredundancy). This mediation tool might provide information about other users or machines to the user (such as position,status, conditions, or plans), and could be used to coordinate group activities. Communications could also be stored forlater review or reference, and translation between communications formats (synchronous / asynchronous, or audio / textconversion) could be performed.

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Wearable computers could support continuing education and training, or just-in-time learning. For example, during along-duration space flight, a doctor might need to perform a surgical operation not covered in previous training, or notrecently practiced. Wearable computers could be used to provide access to domain specific databases (i.e., a soldierhiding out behind enemy lines uses his wearable computer to confirm what plants in the area are edible). With the rightinterfaces, wearable computers can provide augmented reality or virtual reality for training and simulation. Retraining orsimulation capabilities are especially important during long-duration space flight: the complexity of space missionsrequires the crew to be proficient in the use of a huge number of complex systems. For example, on-orbit astronauts mayneed to refamiliarize themselves with a particular piece of equipment through simulation due to a long period of timebetween their original training and operation of the equipment during a critical phase of a mission. One of the factorsinvolved in the crash of a Progress supply vehicle into the Mir Space Station in 1997 may have been the significantprocedural changes made prior to the attempted rendezvous and a lack of recent training with the rendezvous systems.

Many of the serious challenges encountered during exploration in extreme environments are psychological in nature(Stuster, 1996). Wearable computers have the capacity to provide psychological support by serving as a creative outlet:explorers might use a wearable computer as a tool for music composition, writing, drawing, imaging, photography, orvideo capture. A wearable computer might also function as a game playing machine or a multimedia display device (forprivate or shared displays of movies or music, for example). This may help users cope with the boredom that is oftenencountered in extreme environments during periods of inactivity. Such a device could also serve as a virtual privatespace, customized to an individual. Explorers might use such a device to communicate with family or friends in privacy,or to store personal documents or keep a personal journal.

A Case Study: Wearable Computing in Simulated Weightlessness

The authors began a project in 1998 to build and test a flexible wearable computer system for astronauts that serves asa biomedical monitoring device and multipurpose tool. The specific aim of project NIMBLE (a Non-InvasiveMicrogravity Biomedical Life-sciences Experiment) was to measure the effects of micro-gravity and hyper-gravityenvironments using pulse-oximetry and electrocardiography, while providing a cognitive aid for the user (the use of thewearable computer as a checklist was compared with the use of a paper checklist).

The wearable computer system was based upon a commercially available wearable computer from XybernautCorporation, the Mobile Assistant IV, and included a wearable central processing unit (CPU), a head-mounted display,

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and a wrist worn keyboard. The wearable computer performed data collection for an electrocardiography system, andfor a serial-port-based pulse-oximeter sensor. A general block diagram of the experimental setup and analysis approachis shown below:

Data Collection and Analysis Block Diagram

The system was built, ground tested, and later flown on the NASA KC-135 aircraft as part of the NASA ReducedGravity Student Flight Opportunities Program in March 1999. Two flights on the KC-135 with four sets of 10 parabolasper flight yielded a total of 80 parabolas for testing of the system in simulated weightlessness. About 20-25 seconds ofsimulated weightlessness was available during each parabola, and while continuous biomedical monitoring was beingperformed, checklist evaluation sessions (each 15 seconds long) were performed. Tight choreography of activitiesduring the experiment was made possible only by experiment management and data collection software that had beenwritten and developed for the wearable computer. Two flight-crew members (acting as subjects) flew on the KC-135per flight, each with a wearable computer system. The author is shown on the next page wearing the wearable computersystem during flight.

Heart rate recordings obtained during repeated parabolas clearly demonstrated the dynamic response of thecardiovascular system to repetitive exposure to simulated weightlessness and 2-g conditions:

Further analysis of the biomedical data illustrated the importance of reducing the effect of outside disturbances (such asmovement artifacts or drug effects on biomedical sensors.

In addition to successfully demonstrating wearable computer-based biomedical monitoring, the system also allowedsubjects to simultaneously perform a series of simple tasks (such as pushing buttons, turning dials, etc.) with guidancefrom either a paper checklist or the wearable computer. Biomedical monitoring and cognitive aiding functions could

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therefore be performed by the system in a simultaneous fashion. The chart below illustrates checklist completion timesfor subjects using the wearable computer checklist or the paper checklist under all experimental conditions includingpre-flight, simulated weightlessness (0-g), 2-g, and post-flight testing.

While the task completion times were lower for the wearable computer than for the paper checklist, the differences intask completion times were not statistically significant. Post-flight results also indicated that a significant learning effectwas at play. Subjects’ subjective ratings suggested that the wearable computer checklist was easier to use in thesimulated weightlessness and 2-g environments.

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Overall, the system demonstrated the need for lower-mass, lower-profile, and lower-power wearable computers. Thecommercially available Xybernaut system was quite bulky, and on one occasion tangled wires resulted in a hard landingon the padded floor of the KC-135 aircraft by two of the subjects at the end of a parabola. In order to provide futureastronauts with wearable computing platforms that do not interfere with their mobility, future wearable systems must besignificantly less encumbering and more body conformal.

Future Wearable Computing TechnologiesWearable computing technologies are undergoing rapid advances. Conductive fabrics, sensor mesh fabrics, and washablewearable computers have been designed or demonstrated (Post, 1997a). Smaller, lighter wearable computers have beendeveloped, such as a 360 gram prototype, developed by IBM (see figure). Micro-Electro-Mechanical-Systems (MEMS)sensors have been developed for noninvasive biomedical monitoring, and wireless sensors are under development. TheMIT Media Laboratory has demonstrated data and power distribution using the body electric field (Post, 1997b). Human-based power generation for wearable computing has been demonstrated using piezoelectric materials embedded in shoes,and other power generation mechanisms for human-powered wearable computing have been proposed (Starner, 1996).See-through micro-displays, or micro-displays embedded in glasses have also been developed.

A Vision For The FutureWearable computers have the potential to evolve into systems about as encumbering as clothing, and ultimately may bepartially or completely human powered. Wearable computers will be used in extreme environments here on Earth andin microgravity. Researchers may use wearable computers to support science activities and operations research at Marsanalog sites such as Devon Island or the McMurdo Dry Valleys in Antarctica. Wearable computers may be used to study

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and support the exploration process, to coordinate research activities or observations, and to support distributedcollaboration during real or simulated extravehicular activities between a field team and “base camp.” Wearablecomputers will help take humans to Mars, and will ultimately be in everyday use, in one form or another, by manypeople on Earth.

Wearable computers have the potential to improve the everyday lives of people around the planet, and those peoplefortunate enough to journey off the planet. In extreme environments, wearable computing technologies have thepotential to make the difference between mission success and failure – because they help empower the strongest link inthe chain: the humans.

AcknowledgmentThis work was supported by the National Science Foundation Graduate Research Fellowship Program.

References(Gutterman, 1999) L. Gutterman, PC-Based Test Systems in Harsh Environments, IEEE, 1999.(Mann, 1998) S. Mann, Humanistic Computing, MIT Media Laboratory, Proceedings of the IEEE, Vol. 86, No. 11, November 1998.(Ockerman, 1997) J. Ockerman, L. Najjar, and J.C. Thompson, Wearable Computers for Performance Support, IEEE, 1997.(Post, 1997a) E.R. Post, and M. Orth, Smart Fabric, or Washable Fabric, IEEE International Symposium on Wearable Computers,

Cambridge, Massachusetts, 1997.(Post, 1997b) E.R. Post, M. Reynolds, M. Gray, J. Paradiso, and N. Gershenfeld, Intrabody buses for data and power, IEEE, 1997.(Rhodes, 1997) B.J. Rhodes, “The wearable remembrance agent: a system for augmented memory,” Proceedings of the First International

Symposium on Wearable Computers, Cambridge, Massachusetts, October 1997, pp. 123-128.(Rogers, 1997) E. Rogers, R. Murphy, and C. Thompson, Outbreak Agent: Intelligent Wearable Technologies for Hazardous Environments,

IEEE, 1997.(Starner, 1996) T. Starner, Human Powered Wearable Computing, IBM Systems Journal, Vol. 35, Nos. 3&4, 1996.(Stuster, 1996) J. Stuster, Bold Endeavors, Naval Institute Press, Annapolis, Maryland, 1996.(Thorp, 1998) E. Thorp, The Invention of the First Wearable Computer, IEEE, 1998.(Wearables, 2000) Wearables, MIT Media Laboratory Wearables Group (http://www.media.mit.edu/wearables/).

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WB-B2B – A Web-Based Tool For International Project Management

Christian Breu; Norbert Meckl; Patricia Shiroma-Brockmann; Michael Bosch[2000]

AbstractFor the development of the first manned mission to Mars, thousands of industrial contractors, universities, and researchinstitutions will need to work closely together. Important project data, such as project progress, performance, deadlines,costs and cash flows, will need to be transferred between contractors and their subcontractors. The technicalimplementation of these interfaces will be quite challenging, because the project participants often use different projectmanagement software. This makes the automatic integration of data much more difficult. As a result, costly and time-consuming manual integration is usually necessary.

In order to alleviate this problem, the European Space Agency (ESA) requires all contractors to use the same software:ECOS (ESA COsting Software). With ECOS, the electronic invitations to tender can be distributed electronically bythe contracting agencies. Subcontractors send their proposal bid data electronically to the next higher contractor, whocan then integrate these data in their proposal bid automatically. Other software packages have extended this philosophyto include completion of all phases of the entire project. The disadvantage of this method is that one particularcontractor could be forced by each of their different customers to use a special software package for projectmanagement.

WB-B2B (Web-Based-Business-to-Business) is a software system, which solves the conflict between internal andexternal integration. This tool integrates all project data over the entire project life cycle across enterprise boundariesand over multiple hardware and software platforms by using the Internet. Both the call for proposals as well as thedevelopment of proposal bids on each contractual level can be conducted over a B2B platform. Furthermore, the e-procurement interface makes it possible to connect to already existing virtual B2B market places. In this paper, WB-B2B and its possible application in an international Mars mission will be presented in detail.

IntroductionThe development and production of interplanetary space flight systems present challenges, which can hardly becompared to other branches. Especially for manned missions, technically perfect system solutions need to be developedin order to assure safe missions. Even for missions carried out by a single country, an organization which guaranteescooperation between main contractors and subcontractors, government agencies, universities and research institutes isnecessary. A project as large and as complex as a manned Mars mission requires a division of labor among highlyqualified specialists, departments, enterprises and scientific institutions. In addition to technicians, experts in the naturalsciences, computer sciences, medicine, business, law, and in their operation and utilization are also necessary.

If the first manned mission to Mars is carried out as an international program, additional management efforts due to thefollowing characteristics are required: Development and finances must be regulated by contracts between theparticipating countries; different languages, cultures and legal systems must be taken into account; therefore, the projectinformation system must guarantee an interdisciplinary integration of different countries, companies, specialists andcontractors (Bosch, 1999).

In this paper, the disadvantages of traditional project information systems during the following phases will be discussed:invitation to tender, preparation of proposal bids, project planning and project execution. Next, a prototype for the Web-Based B2B System developed by the authors will be presented. This system uses new, Internet-based technology tosolve the problems discussed previously.

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Christian Breu and Norbert Meckl; University of Regensburg / Patricia Shiroma-Brockmann; University of Applied Sciences NuernbergMichael Bosch; University of Applied Sciences Albstadt Sigmaringen; Anton-Guenther-Str. 51; D-72488 Sigmaringen; Email: [email protected]

Invitation To Tender And Tender IntegrationOn multinational projects, the external cooperation between project partners is organized according to contracts betweenindustrial prime contractors, main contractors and subcontractors. The signing of contracts between prime contractorsand subcontractors is preceded by a multi-hierarchical proposal phase.

During the invitation to tender phase, the goal is to use a competitive environment in order to either find potentialcontractors who can provide certain systems and services for the lowest possible costs, or to receive the maximum amountof systems and services for a given budget. The geographical return rule is an additional reason for the inclusion ofsubcontractors within the jurisdiction of the European Space Agency (ESA). Most of the time, the space agency for agiven international partner names a prime contractor who is responsible for the completion of a given project. The primecontractor holds a turn key contract and is thus fully responsible for the leadership and management of the entire project,for supervising the subcontractors and for the development, integration and delivery of the system (Korbmacher, 1991).

The invitation to tender and proposal integration phase is conducted as follows. First, the space agency issues aninvitation to tender to all potential prime contractors. Project requirements, cost and schedule plans are also sent alongwith this invitation to tender. While putting together their proposal bids, the potential prime contractors decide whetherthey will outsource portions of the project to subcontractors. If subcontractors are chosen, they also have to makecorresponding decisions.

Each potential subcontractor puts together a proposal bid and submits this bid to their contractor. The contractor thenevaluates these bids and selects the best one. The selected bid must then be integrated into the contractor’s proposalbid. Finally, the contractor’s bid is submitted to their contractor on the next higher hierarchical level. This recursiveprocess continues until the potential prime contractors have submitted their bids to the space agency. The space agencythen selects one of the prime contractors. Figure 1 shows a graphical representation of this process.

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Figure 1. Invitation to Tender and Tender Integration

The external project organization for each of the international partners is specified in the contracts between contractorsand subcontractors. As shown in Figure 2, each subcontractor serves in turn as contractor for their subcontractors.

Figure 2. Multi-hierarchical Relationships Between Contractors and Subcontractors

The process described above originally required a tremendous amount of time and money, because everything was doneon paper. Schedule delays and additional costs were incurred by sending the invitations to tender and the proposal bids bymail. Unjustifiably high costs and error rates were caused by having to manually reenter data from one system into another.

In order to combat these problems, during the 1980’s the European Space Agency (ESA) introduced the ESA CostingSoftware (ECOS). ECOS makes it possible to process the invitations to tender and the integration of the proposal bidsby computer. The goal of this system is to allow contractors to submit proposal bids either on a diskette or via modem.This is especially helpful for space projects where several industrial subcontractors are involved. ESA requires theirindustrial contractors to use ECOS for certain projects (ESA, ECOS User’s Manual, 1992). Worldwide, ECOS was thefirst system of this type.

During the proposal phase, ECOS helps with the development of the Product Tree (PT) and the Work BreakdownStructure (WBS). Under certain conditions, each subcontractor can extend the PT and WBS from their contractor,simply by adding additional nodes. In this manner, stepwise refinement of the project structure is achieved.

The WBS is generated in ECOS together with the Invitation To Tender (ITT). An ITT is an invitation to potential primecontractors to submit a proposal for a given project. Space agencies start the proposal phase by sending ITT’s topotential prime contractors. This process continues recursively down to the lowest level of the project organization.Each subcontractor participating in the proposal can extend the systems structure and the WBS to reflect their

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contribution. When a contractor decides to outsource work packages to a subcontractor, he is responsible for definingITT’s for each of the potential subcontractors. Because each contract can be subdivided into a contracted part and anown part, ECOS also requires the definition of an ITT for the part completed by the contractor himself (ESA, ECOSUser’s Manual, 1992).

Figure 3. Definition of ITT

ITT 1 is defined for Subcontractor 1; ITT 2 is defined for Subcontractor 2. The contractor is solely responsible for theintegration of the entire system; he does not participate in the development of the subsystems. After the ITT’s have beendefined, the contractor uses ECOS to generate ITT files. These ITT files are then sent, either on diskette or via modem,to the responsible subcontractors. WBS nodes within the jurisdiction of one subcontractor can not be worked on by thecontractor. Once the contractor has defined an ITT as ready for Data Entry, then the system structure and the WBS cannot be changed by a subcontractor. The subcontractor is only allowed to enter technical specifications, costs andschedule data for existing nodes. Once a contractor has defined an ITT as ready for ITT-Handling, this implies that itwould be possible to include additional subcontractors. Once the ITT’s have been sent to potential subcontractors, thenthe contractor has completed their handling of the ITT’s. The next process step consists of the integration of the tenderbids from the subcontractors (tender integration) within the contractor’s own proposal bid. The contractor’s bid is then,in turn, integrated into the proposal bid at the next higher level (ESA, ECOS User’s Manual, 1992).

The proposal process can only be conducted as described above if all of the participating enterprises utilize ECOS. Ifa contractor has other customers in addition to ESA, then the contractor would be required to use different proposalsystems for each customer. This could lead to an unmanageable number of different systems for each contractor.

Project ExecutionDuring the project execution phase, many different types of data need to be exchanged between the contractors andsubcontractors shown in Figure 2: schedule data, performance data, technical data and financial data. Furthermore, datafrom each subcontractor has to be aggregated for the contractor on each of the next higher levels, all the way up to theprime contractor. If all contractors for one project are allowed to choose their own project management software, thendifferent data formats and different integration methods lead to incompatible systems. The result is costly manualintegration work at the interface between contractor and subcontractor.

Special project management systems which can integrate multiple enterprises and which have adapted ECOS methodsfor project execution already exist. The ISPMS prototype, which was developed at the University of Regensburg in themiddle of the 1990’s, is an example of such a system. If all project participants are required to use ISPMS, thencompletely automatic integration of project management data for multiple enterprises can be achieved without anyadditional manual data entry. During the project planning phase, the plan data for each subcontractor can be transferredto the contractor on the next hierarchical level. These data can then be integrated into the contractor’s project plan. This

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continues on each higher hierarchical level, until a complete project plan has been developed on the prime contractorlevel. Data for the technical and administrative project control (technical performance control, task performancecontrol) can be aggregated and integrated in the same way, for each of the hierarchical levels. During project execution,data about the actual state of the project progress can be compared with the project plan. Furthermore, the original plancan be revised and adjusted to reflect the current project situation. The implementation of the software necessary forthis concept is relatively simple and inexpensive. All of the programs necessary for the ISPMS project managementsystem run on a standard PC. ISPMS can be installed for each of the project participants (Bosch, 1997).

Problems With Traditional SystemsAs stated previously, the problems associated with data redundancy and the integration of data between enterprises canbe avoided. This can be achieved if all project participants use the same standard, unified project management systemfor both the proposal phase as well as the project execution phase. On the other hand, though, each contractor isconfronted with a problem: each of their customers could theoretically require them to use a different projectmanagement system for each project. This could result in an unacceptable number of different project managementsystems (PMS) on the level of a certain contractor. Figure 4 illustrates this problem graphically.

Figure 4. Customer Software Requirements from the Perspective of a specific Contractor

The challenge is to develop a standard information system that can be used for multiple enterprises, without limiting thesoftware independence of a single contractor.

Web-Based B2B ConceptWB-B2B is an Internet-based project management platform that runs on a Web-server. It is based on a centralizeddatabase with a Web interface, which means that data input and output is performed with a Web browser over theInternet. Each user sees his own special views of the database, generated by dynamic, individually generated forms.User authorization is conducted by a unique login password.

The proposal phase is conducted in the following manner. First, on each hierarchical level of the project, a contractorenters all of the necessary information into the central database. Potential subcontractors are invited to submit theirproposals. This invitation to tender can be transferred over several different electronic media and does not need tocontain the project details. The detailed information can be obtained by logging into the specified address on theInternet. Potential subcontractors can log into the system and are identified by a login password specified by thecontractor. They then can see the detailed information about the invitation to tender and can submit their proposal bidsover the Internet. Once a proposal has been received, then the appropriate contractor is automatically notified either viaE-mail or via cellular telephone using the Short Messaging System (SMS). The contractor can immediately view theproposal bid over the Internet with the WB-B2B system. In addition, WB-B2B performs an analysis and suggests apreliminary selection of the proposal bids.

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Contractors can generate additional project nodes on lower hierarchical levels for multiple subcontractors. The result isa project structure, where each subcontractor is only allowed to view data for their respective subproject. The contractorretains control over both their own data as well as that for the hierarchical level directly beneath them. Once a contractorhas all of the project documents (e.g., technical specifications, schedules and planned costs) in digital form, then thesedata can also be stored in the database. These data can then be viewed at any time by the contracting agency. After acontract has been awarded, data and user rights that are no longer needed can be deleted.

During the project execution phase, each participating contractor is assigned a client certificate. Client certificates serveas an additional guarantee of authenticity when used together with a login password. WB-B2B also offers acommunication platform. Messages can be posted to project nodes. Electronic documents can be discussed andsuggestions for improvements can be made.

Comparison of data during the project execution phase occurs on the contractors’ respective internal informationsystems, using their preferred database and project management software. The necessary data transfer can be conductedusing either the Internet-based forms interface already presented or using other agreed upon universal interfaces, suchas ASCII files or SQL (Structured Query Language). The results of the data comparison can then be uploaded to theInternet (according to the “push” principle). Alternatively, if the enterprise is willing to allow the WB-B2B systemaccess, can be directly accessed by the WB-B2B system (“pull” principle).

Changes in planned schedules, costs or products which may occur at any point in the project structure during the projectexecution phase are sent to the next higher level contractor, either via E-mail or via SMS. At the same time, these changesare immediately recorded in the database and automatically included in the aggregated data on the next higher level.

Technical ImplementationThe logic of the application software is embedded in a Java program, which runs on the centralized Web server. Thisprogram handles the interface between the database and the Web application. It is responsible for verification of users,database access, data processing, the application logic and the generation of Web content.

The system is organized according to the “thin client” principle. This means that the server is responsible for performingall of the program processing. On the client side, all that is necessary are relatively inexpensive PC’s, Macintoshes orUNIX computers with Internet connections and relatively recent browser software (e.g., Internet Explorer, NetscapeCommunicator, version 3 or higher). As a result, the enterprises usually will not have to buy any additional hardwareor software.

Requests from client computers are handled by Java Servelets and Java Beans (Sun Microsystems), which translate theserequests into database queries. The resulting data are then sent to Java Server Pages (JSP). The JSP convert these datainto HTML (Hypertext Markup Language) pages, which can be viewed with the browser software. These HTML pagesare then sent to the client computer. By using the programming language Java, the Web server is independent from anyplatform. This means that the same software can run on a number of different operating systems, for example, WindowsNT, LINUX and Solaris.

Access to the centralized database is done with the standard database interface, SQL. The advantage of using SQL isthat for each project the best-suited database management system can be selected. For example, Oracle could be usedfor larger projects and MySQL could be used for smaller projects.

Javascript is used on the client side only for the navigation of web sites, error messages or for input validation checks.Input validation checks ensure that the user is informed of input errors before the data is even sent to the server.

As an alternative to simply displaying the data in a browser, WB-B2B also offers additional data transfer modes. XML(eXtended Markup Language) is becoming increasingly important as a meta-data definition language. XML is a

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universal, platform-independent data format. WB-B2B offers the option of creating and sending project data in XMLformat. WB-B2B’s WAP service, used to send especially time-critical project data to a cellular phone, is based on avariant of XML, called WML (Wireless Markup Language). In the near future, the transfer of voice-based Web contentbased on Motorola and IBM’s VoiceXML standard is also planned.

Security IssuesWB-B2B fulfills the current security standards for e-business applications. Once a user has logged into the system, thesession is automatically closed if the user hasn’t sent any requests for 10 minutes. After each session, the user’s personaldata are stored in order to generate the specific Web content he is authorized to view. During each session, encoded, atemporary “cookie” is stored, which is then deleted when the session is closed. Hostile, external accesses to the databaseare prevented by a firewall. Thus, it is not possible for unauthorized persons to read, change or delete data.

A “Man in the Middle Attack” is when an unauthorized person attempts to listen in on or to falsify data transfers. Inorder to prevent this from happening, a secure Internet connection will be established using SSL (Secure Sockets Layer)encryption. SSL technology takes a message and runs it through a set of steps that “scrambles” the message. This isdone so that the message cannot be read while it is being transferred. This “scrambling” is called encryption. Whenthe message is received by the intended recipient, SSL unscrambles the message, checks that it came from the correctsender (authentication) and then verifies that it has not been tampered with. SSL uses digital certificates (or justcertificates) to bundle important information together to identify a server or a user. This identification comes in the formof things like the organization name, the organization that issued the certificate, the organization’s email address,country, and of course their public key (the part that “scrambles” a message) (www.ssl.com, 2000).

Bibliography1. Bosch, Michael, Commercialization of Management Know-How Generated by the ISS-Program, in: International Space Station: The Next

Space Marketplace (Space Studies Series Vol. 4), Kluwer Academic Publishers, Dordrecht, 1999.2. Bosch, Michael, Management internationaler Raumfahrtprojekte, Gabler Verlag, Deutscher Universitätsverlag, Wiesbaden, 1997.3. European Space Agency, ECOS User’s Manual, DRAFT VERSION, PSS-06-101, Issue 2, Cost Analysis Division, ESTEC, ESA, Noordwijk,

1992.4. Korbmacher, Eva-Maria, Organisationsstrukturelle Problemfelder im überbetrieblichen Projektmanagement, Steuer- und Wirtschaftsverlag,

Hamburg, 1991.5. Secure Sockets Layer, Homepage, www.ssl.com, 2000.

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Wet Mars: Plentiful, Readily-Available Martian Water and its Implications

Roderick Hyde, Muriel Ishikawa, John Nuckolls, John Whitehead & Lowell Wood[1999]

AbstractWater and its major constituent, oxygen, in large specific quantities are essential for maintenance of human life.Providing them in adequate quantities is widely believed to be a major challenge for human exploration and settlementof Mars. The Martian regolith isn’t known to bear either water or hydrogen, the ice-rich Martian polar regions arethermally inhospitable, and the measured water content of Mars’ thin atmosphere represents a layer of liquid water ofaverage thickness only ~1% that available on the Moon, or ~0.001 cm. Crucially, however, the atmospheric Martianwater inventory is advected meteorologically to every place on Mars, so that the few cubic kilometers of liquid water-equivalent in the atmosphere are available anywhere, merely for the effort of condensing it.

Well-engineered apparatus deployed essentially anywhere on Mars can condense water from the atmosphere in dailyquantities not much smaller than its own mass, rejecting into space from radiators deployed over the local terrain thewater’s heat-of-condensation and the heat from non-ideality of the equipment’s operation. Thus, an optimized,photovoltaic-powered water-condensing system of ~0.3 tons mass could strip 40 tons of water each year from ~104

times this mass of thin, dry Martian air.

Given a 490 sec Isp of H2-O2 propulsion systems exhausting into the 6 millibar Mars surface atmosphere and the 5.0km/s Martian gravity well, ~40 tons of water, two-thirds converted into 5:1 O2/H2 cryogenic fuel, could supportexploration and loft a crew-of-four and their 8-ton ascent vehicle into Earth-return trajectory. The remaining H2O andexcess O2 would suffice for half-open-cycle life support for a year’s exploration-intensive stay on Mars.

A Mars Expedition thus needs to land only explorers, dehydrated food, habitation gear and unfueled exploration / Earth-return equipment – and a water / oxygen / fuel plant exploiting Martian atmospheric water. All of the oxygen, waterand propellants necessary for life-support, extensive exploration and Earth-return can be provided readily by the hostplanet. Crewed exploration of Mars launched from LEO with only 2 Shuttle-loads of equipment and consumables – acommercial total cost-equivalent of ~$650 M – thereby becomes feasible.

The most challenging current problem with respect to human expeditions to Mars is escape from Earth’s deep, 11.2 km/sgravity well, and is largely an economic issue. Living on Mars, exploring it extensively and returning to Earth, eachhitherto major technical issues, are actually much less difficult, thanks in no small part to the effective “wetness” ofMars. Similar considerations apply to other water-rich locations in the Solar system, e.g., Europa.

Introduction and SummaryWater is the sine qua non of human life. Not only is it essential per se for use in preventing eventually-fatal dehydrationof our tissues, but its major constituent, oxygen, is essential in molecular form as the ultimate electron-sink in thechemical reactions which power all human metabolic processes. We die without molecular oxygen gas for respirationin a matter of minutes, without liquid water for tissue-rehydration in a handful of days. To stay alive then, we mustimmerse ourselves in environments that aren’t completely devoid of water, just as our distant ancestors requiredenormously water-rich ones.

Off-Earth human exploration and settlement appears especially challenging, then, for liquid water is known to be presentin very few locations of near-term interest for exploration of the inner Solar system – actually, precisely none. Thegeneral mind-set has been that Mars is exemplary of such water-starved, innately inhospitable locales, for the verymodest quantities of water which exist on its surface – by terrestrial standards, at least – seem to be tightly locked-upin polar caps of forbiddingly low temperature. Even the vacuum-enshrouded Moon, from our current, relatively poorly-

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Corresponding author. Also Visiting Fellow, Hoover Institution, Stanford University, Stanford CA 94305-6010.All authors are affiliated with the University of California, Lawrence Livermore National Laboratory, Livermore, CA 94551-0808

informed perspective, might seem more attractive to water-addicted life forms such as our own; for its generally fine-powdery surface is known (from Apollo studies) to have several ppm of solar wind hydrogen implanted in it, which canbe released by moderate-temperature roasting of this “soil.” The corresponding amount of water-equivalent hydrogenin the top 10-20 meters of continually meteorically-churned lunar regolith is a liquid sheet of about 0.1 cm thickness, or1000 metric tons of water per square kilometer of mare surface – everywhere! The dusty, wind-swept Martian surfaceseems desert-like in comparison.

The purpose of this paper is to invite general attention to the facts that Mars is actually reasonably water-rich; that theentire surface of Mars is truly covered with a very low-density, albeit deep, ocean of water; and that human explorationand settlement of Mars are therefore much less technically challenging – and far less economically demanding – thanhas been generally believed. This general point applies in a comparably compelling manner to other water-richlocations in the Solar system, e.g., the outer Galilean moons of Jupiter.

In particular, as specialists have long understood, the thin (~6 millibar surface-pressure) Martian atmosphere has thesame specific water content as is found in the Earth’s air over Antarctica – about 1 milliTorr vapor pressure, in theMartian case. Also, the pertinent transport properties of the Martian atmosphere are particularly conducive tocondensation of this atmospheric moisture with modest specific quantities of equipment. Deployment and operation ofremarkably small amounts of optimized equipment may readily extract enough liquid water to not only provide the feed-streams of oxygen and water to life-support systems for human explorers or settlers, but can also provide the few-foldgreater quantities of liquid hydrogen and liquid oxygen needed to support vigorous rocket- and ground-vehicle-supported exploration of Mars, as well as supply the far-larger quantities of cryogenic propellants required for rocket-powered return-to-Earth from the Martian surface.

Martian explorers and settlers thus need bring to Mars little more than themselves, life-support and habitationequipment, dehydrated food (sufficient until greenhouse operation provides adequate foodstuffs), a Water Plant (withinternal power-supply) and exploration and Earth-return vehicles. Water extracted from the Martian atmosphere – andproducts readily derived from it – will fill in the rest of the traditional expedition’s mass budget – and this mass budgetfraction characteristically is the dominant one, as Table 1 and Figure 3 indicate. Exploration and settlement of Marsthereby may be several-fold easier, in terms of required mass leaving the Earth in trans-Mars trajectory, than has beenestimated hitherto – and thus may be made to commence significantly sooner. Specifically, as little as 2 Shuttle-loads(or commercial space-launch-equivalents) of equipment and supplies positioned in LEO may suffice to launch a full-fledged manned mission to Mars with a crew of 4.

In the following sections, we first review salient properties of the Martian atmosphere, including aspects of itsmeteorological repertoire. We then consider the form-and-function of equipment mass-optimized to extract water fromit, note the quantities of water of interest to support the full spectrum of activities of early exploration teams, and suggestthe steps to be taken toward the reasonably near-term implementation and demonstration of these prospects. Weconclude by noting the rather striking implications of these results for initial Mars exploration mission-architectures.

Pertinent Properties of the Martian AtmosphereOur present knowledge of the pertinent features of the Martian atmosphere is derived from the Viking Lander 1 and 2data sets, supplemented by the Pathfinder results of 1997. The Viking data set is of primary interest, as it representsessentially all that we know of a quantitative nature about Martian atmospheric seasons, and because it sampledatmospheric properties at two quite different locations on Mars. At that, it’s quite imperfect, as surface-level water vaporconcentrations were measured only indirectly, and only two sites on Mars – a planet whose meteorology is apparentlynot much less rich than that of the Earth – were studied only over a single full year’s variations, i.e., over an interval of650 sols.

The primary data of present interest are summarized in Figure 1, which, at the “bottom line’’ (represented by the “NewHouston” plot, which is the best-estimate of the globally-averaged value-vs.-time of the Martian atmospheric water

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content) indicates that the global annual average of water content of the Martian atmosphere is about 2x10-6 kg/m3. Thiscorresponds to a bit more than 1 milliTorr vapor pressure. The right vertical axis of this Figure indicates the saturationtemperature for the corresponding water vapor pressures / gas densities on the left vertical axis. As may be readilyappreciated, the saturation temperature for the global annual-averaged water vapor pressure is about -74ºC, or 199ºK,while an order-of-magnitude lower vapor pressure is seen at -88ºC, or 185ºK, and another order-of-magnitude reductionis seen at -100ºC, or 173ºK. In somewhat more familiar terms, the average relative humidity of the Martian wintertimeatmosphere is about 5-10% – not much less than mid-continental wintertime terrestrial conditions.

Stripping water out of the ‘’average’’ Martian atmosphere thus consists of cooling it to a temperature of no more thanabout 185ºK, providing a convenient surface onto which this now-supersaturated Martian “air” can deposit and/or growice crystals, and maintaining this condition sufficiently long (in the particular cooling geometry employed) foressentially all water molecules in the parcel of chilled air to ‘’see’’ the ice-covered surface via diffusive-and-convectivetransport. This whole process really isn’t very complicated – splotchy hoar frosts on the nearby Martian surface wereimaged regularly during local wintertime shortly after dawn at the Viking Lander sites, i.e., the Martian surface cooled-by-radiation sufficiently most every winter night to condense visible quantities of water from the overlying atmosphere.

Mass-Optimized Water Extraction from the Martian AtmosphereThe issue of present interest is the design of equipment of minimum mass with which a unit quantity of water can beextracted from the Martian atmosphere per unit of time.

As we will also mention quantitatively below – but which is intuitively obvious to those who have considered thesematters in any detail – the present and near-term specific (i.e., per-kg) cost of soft-landing equipment on the Martiansurface is so great that it exceeds the specific cost on the Earth’s surface of virtually every type of human artifact.Simply stated, the per-kg transportation cost from Earth-surface to Mars-surface is so huge that it exceeds the purchase-cost here on Earth of a kilogram of almost everything. It is therefore ‘’good engineering practice’’ in the Mars-missionarchitecture and design processes to drive the mass of any equipment that needs to go to Mars to as low a value as everpossible; no matter how expensive it may then be to fabricate here on Earth. The total cost to create and then transportit to the Martian surface will thereby be minimized. This is the approach that we take toward the optimized design ofequipment for extracting water from the Martian atmosphere.

Our basic design approach is to use counter-current airflow through the water-extracting apparatus, and cool-as-requiredthe coldest spot (T = 180ºK) in the system radiatively. As noted above, water starts condensing from the most moistMartian air at ~200ºK, and 95+% (global- and time-averaged) of the Martian atmospheric water is stripped out at 180ºK.This water-condenser’s incoming and exhaust airflows are cross-coupled thermally with heat-pipes terminating on eachside on super-high surface-to-volume metal-to-gas finned / spiked surfaces. Photovoltaically energized electric motor-driven fans make up condenser-internal aero-drag losses (with ~1.5 kWe of H2/O2 fuel cell-derived power beingemployed during nighttime and milder dust storms). See Figure 2.

The core technical issue in overall system design is trading off condenser drag-loss vs. condenser mass vs. condenserair-blower electrical power (i.e., photovoltaic array or PVA, power-conditioning and fuel-cell masses) vs. condenserirreversible delta-T (the temperature differential between the exhausted air relative to the incoming air arising from finiteair flow-speeds and imperfect heat-exchange), in order to minimize total system mass (including that of the system’sradiator, which sizes and masses nearly linearly in proportion to delta-T – exactly linearly, after the “base” 2.5x108

J/day, or ~2.5 kW – of heat-of-condensation of 100 kg of water/day, or ~1 gm/sec, is subtracted off the bottom of thesystem’s thermal radiation budget). The only major constraint on the radiator is that its working-surface be shaded, ifit’s going to be operated in daytime, as well as nighttime; it may thus be split into AM and PM sections (if it’s deployedin east-west symmetry; splitting is less necessary if deployed in north-south symmetry at a higher-latitude location ineither Northern or Southern Hemisphere). A minor constraint on the radiator’s design is that it’s operating in 6 mbar“air,” so that it needs some “standard” thermal decoupling from the local atmosphere, e.g., a transparent film-boundedlayer or two of trapped still air, which involves some (modest) associated mass-expenditure.

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Our estimate is that the ~109 gm/day of Mars-air – processed through the ~102 m2 condenser system inlet-aperture at 10m/sec mean speed – will require of the order of 109 J/day (or ~10 kW, CW) of heat stripped from it, net. This correspondsto a flow-stream irreversible delta-T of 1 J/gm-equivalent, or 44 J/mole (of CO2), or ~10 cal/mole, or a ~1.5 K delta-T,split into two roughly equal portions, in the metal-to-air interfaces on each side of the counter-current flow (with theinterposed heat-piping being taken to be a thermal superconductor, a quite good approximation). This is ~5% of the totaltemperature change through which the processed air typically (i.e., in the diurnal-average) will be cycled, so that themean-reversibility of the condenser system is taken to be 95%. (We expect that this inlet-air flow-speed will suffice forcentrifugal separation of all but the smallest dust particles from the inlet air-stream, given the low density of the airflow.Electrostatic precipitation will then serve to ‘’polish’’ the inlet flow with respect to very small dust particles, so thatminimal solids-removal processing (e.g., by a regenerable, multi-stage filter and ion-exchanger) of the extracted waterwill be required prior to its storage or electrolysis. We therefore expect that this system may be made to work effectivelyin all Martian dust storms of sufficiently low optical density that PVA-derived electrical power will be available.)

If the Martian air-mass exits the 100 m2 aperture condenser with the reference entry-speed of 10 m/sec, this representsonly 850 W of kinetic energy, a modest fraction of the total power budget of the system, as will be seen below, so thatuse of pressure-recovery features probably isn’t indicated. A simple electrically powered blower system provides thenecessary ventilation of the condenser. An electrical-watt-to-flow-watt efficiency of ~0.71 is realistic for powered,optimized airfoils operating in the high Reynolds number conditions characteristic of the Martian surface atmosphere.Electrical power input to the condenser’s air-moving system thus is ~1.2 kWe, assuming use of a 95% efficient fan-motor.

The system’s radiator, working at 175ºK at an emissivity of 0.85 (i.e., with a radiator system-internal mean delta-T of 5K), sheds (into 2π steradians) about 50 W/m2, so that 250 m2 of open-sky-equivalent radiating surface is required toshed 12.5 kW. The radiator’s area thus is comparable to the sum of the entry and exhaust port-areas of the condenser.(The Martian atmosphere is radiatively reasonably thin in the thermal IR – the current Martian “atmosphericgreenhouse” delta-T is only ~7ºK, compared to ~35ºK for Terra – so the radiator performs almost like it’s radiatingdirectly into space, except that only one side of it is available to shed heat, and the ambient air-&-soil must be kept outof effective thermal contact with the radiator’s cold surface). As noted above, the radiator’s operating surface also mustbe shaded from direct or indirect illumination by either the Sun or the Martian surface. For example, it will be northfacing in northerly latitudes, with suitably thermally decoupled baffles-&-shades positioned to keep it ‘looking’ onlyinto non-Sun-bearing space; the Martian equatorial inclination to its orbital plane of 24° (very similar to Terra’s 23.5°)is usefully large in this respect.

If it’s deemed too tedious to shield the radiator from the Sun-&-surface, the condenser may be operated only when theSun is below the local horizon, and then may heatpipe-couple to a simple radiator lying on the local surface, lookinginto the entire 2ð of the dark sky. In this case, the entire [condenser + radiator + fuel cell] subsystem must be oversizedby two-fold, relative to the operating-all-the-time baseline system, and the photovoltaic array (PVA) simply ‘pumps up’the store of cryogenic H2 and O2 during daytime, for nocturnal use by a ~3 kWe fuel-cell (which also provides ~1.5 kWeto the Base during nighttime intervals). This variant is considered likely to be off the mass-optimum, however; it’s ofinterest if total system simplicity – and (perceived) technical risk – is at a premium.

Periodically – e.g., diurnally – the system will (hermetically) close its entry-and-exit hatches and electrically heat its‘’cold-spot’’ to ~275ºK, so as to liquefy the condensed H2O and gravity-drain it into a sump for pump-transport toelectrolysis-&-cryogen storage, to water storage, etc. (The molten-H2O vapor pressure at 2-3ºC will add only ~6 mbarto the condenser-internal pressure, so that a high-strength shell around the condenser and its hatches is quite unnecessaryto contain the internal gases during the system’s ‘’defrost cycle,” during which interval the dust-scavenging surfaces atthe condenser inlet are also mechanically brushed-&-air-blown clean.) The system then radiatively re-cools to workingtemperatures (in order to scavenge internal liquid water and water-vapor), its hatches re-open and atmospheric water-condensing resumes; the daily defrost-&-regeneration cycle has been completed.

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The actual condenser system likely will be implemented with many identical small modules working in parallel, forreasons of economy in Earth-side prototyping and testing, of simplicity of packaging-for-transit, of ease-of-erection andof system-level reliability-in-operation – although this is likely to be somewhat off-mass optimum. Thus, the condenserper se, the radiator and the PVA functions may well be fully-integrated in each module, so that there will be preciselyno single-point failure-sites in the total system – and so that the system’s capacity can be readily ‘’cut-to-length’’ to meetvarying mission requirements.

Insolation at Mars diurnally-averages about 150 W/m2, or about 15 W/m2 electrical converted with a-Si – or 30 W/m2

converted with high-efficiency, thinned Si – photovoltaic arrays (PVAs). Electrolyzing the (time-averaged) 1 gm/sec ofwater condensed from the Martian atmosphere will require ~15 kW electrical power (time-averaged), or the output of500-1000 m2 of such PVA. The best-current a-Si offers about 1 W/gm at 1 AU AM0, and the comparable value forhigh-efficiency 4-mil Si is ~0.5 W/gm, so that a 15 kW average-power (i.e., 50 kWe initial peak-power) requiremententails ~115 kg of a-Si PVA, or ~230 kg of PVA implemented with thin-crystalline Si, at Mars AM1; a-Si PVA usage istherefore preferred. An option that we consider interesting but haven’t examined in detail features double-use of one-and-the-same large-area deployed surface: as a PVA during daytime and as a radiator-surface at night. If this is done,~500 m2 of effective surface area is required if we condense-and-radiate only at night, which is comparable to the 500-1000 m2 of PVA needed during daytime. If we were to employ a 1000 m2 area, the 2.5X larger radiator surface areawould permit us to operate with a condenser-internal irreversible delta-T which is 2.5X greater, i.e., ~4 K, realizing acorresponding savings in condenser system mass. However, such double-use doesn’t come free; we would have toprovide adequate thermal decoupling of both top and bottom surfaces of the entire radiator-PVA area during nighttime.Thus, unless suitable (atmosphere + soil) insulation of quite modest areal density – <0.05 gm/cm2 – is available, wemight be better off with employing a crystalline-Si PVA and working with the smaller 1.5 K delta-T in the condenser’sair-flow – if we were to pursue this double-use option at all. All these are instances of second-level design issues thatmay be resolved only by comparison of the details of several alternate point-designs, which we have not yet done.

These then are the essential considerations upon which our baseline-design Water Plant mass-estimate of 300 kg (0.3ton) is based. We allocate 115 kg to the PVA, 85 kg to the condenser per se, 50 kg additional to the radiator (-function),10 kg each to system fluidics (fans, piping, meters, valves and pumps) and to a 45 kWe electrolytic cell, 5 kg each topower conditioning, 3 kWe fuel-cell, cryogen liquefaction, and control system, and 10 kg to a flex-wall-implemented,bladder-type water storage module of 0.5 ton capacity. The cryogens, LH2 and LO2, are stored in the same multi-layered, flex-walled bladder-tanks as are employed for primary propellant-storage for the mission propulsion-plant,which have cylindrical symmetry with multi-coaxial-walls with intra-positioned lofted-fiber insulation interleaved withstandard aluminized-plastic multi-layer insulation (MLI), and operate with ullage pressurization only modestly (delta-P~0.3 bars) above ambient pressure. Roughly 70% of this total tankage is not required for the return-to-Earth mission,and thus is left at the Mars Base. See Table 1.

Obviously, we contemplate the pervasive use of the highest strength-to-weight structural materials (e.g., polyaramidfabrics and carbon fiber-composites) and highly mass-economized (e.g., thin-walled) fins, heat-pipes, etc., all employedin optimal designs, in which mass of carefully-selected properties is employed only in amounts actually required fortransport performance or to bear structural loads. We exploit the facts that Martian winds, though of very high peakspeed (~200 km/hour), have only the peak momentum flux density of a brisk Terran breeze, and that there is no Martianrain. At that, our baseline design for all expedition hardware, specifically including the Water Plant, requires the use ofnothing which isn’t commercially sourced – COTS, or commercial off-the-shelf – at the present time. (Nonetheless, wearen’t inclined to argue extensively with those who might choose to design in a less mass-economized manner, and thusto realize a Water Plant with even 2-3 times the mass of our baseline one; the mission-architectural gains realized froma Water Plant of 40 tons-of-H2O/year output capacity are so great that it doesn’t matter greatly whether the Plant’s massis 0.3 ton or 1 ton – so long as it’s quite small compared to 40 tons.)

In concluding this section, we feel obliged to note briefly a lower-likelihood but high-payoff alternative to the approachthat we’ve just outlined. It proposes to exploit the meteorological prospect of reliably-appearing nocturnal fogs on the

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Martian surface, which naturally raises the corresponding technical prospect of erecting large-area, Cottrell-typeelectrostatic precipitators through which the ambient 2-4 m/sec Martian nocturnal breeze would blow the ice / water-droplet-laden Martian atmosphere. The fog would be condensed on the precipitator plates, and the whole precipitatorassembly would button itself up in a gas-tight manner at local dawn; later in the day, it would electrically heat theprecipitator plates to melt the deposited ice-film and transport the resulting liquid-water into a sump. It seems entirelypossible that such a system, with an aperture of ~1000 m2 – 10 X that of our baseline design-value of 100 m2, one factor-of-3 due to the average wind speed being lower than our forced-convection speed and the other due to only 33% duty-cycle, i.e., during the coldest third of the local diurnal cycle – might be quite mass-competitive overall with the baselinesystem just outlined.

If such a system were implemented in a very highly mass-economized, Venetian-blind-like format, it might be feasibleto deploy it by simply unrolling its base across the local landscape, and then erecting it from this base, all perpendicularto the prevailing diurnal breeze direction. Although the electrical power required to operate such a system would be farsmaller than that for the baseline system, a good-sized PVA would still be required in order to convert the large majorityof the electrostatically-stripped Martian atmospheric water to cryo-propellants / fuels and to O2 for the life-supportsystem of the Mars Base. Thus, if nocturnal fogs appear reliably at the expedition’s landing-site, then God graciouslycondenses the water from Martian atmospheric water vapor most every night, and harvesting it from the air by thefigurative waving of electrostatic wands is all that Man need do for his mundane purposes.

Early Expedition Water Budgets and Sizing of Water-Supply EquipmentWe employ basic results from our previous work on the Space Exploration Initiative – i.e., the Great ExplorationProgram proposal – for reference mass-budget numbers for a first manned expedition to Mars. See Figure 3.

These indicate the above-assumed requirement for of the order of 0.1 ton – 100 kg – of water per day, or 1 gm/second,in the time-average, over the duration of the 400-day stay of the expedition crew on the Martian surface, or 40 tons ofwater total. This rate of water-production will suffice for all life-support system needs, all energy requirements forvigorous, long-distance surface Rover- and rocket-performed exploration of the Martian surface – see Figure 4 – andfor all fueling requirements for the ascent stage of the crew’s return-to-Earth vehicle. It represents over 90% of the totalmass which leaves LEO in a conventional Mars exploration mission whose mission-architecture specifies powereddescent of Earth-derived life-support water and oxygen and Earth-return propellants down to the Martian surface – and70% of the total leaving-LEO mass of a more advanced mission-architecture which aerobrake-lands the expedition ontothe Martian surface. See the three basic mission architecture comparisons in Table 1.

The first-level breakdown of the baseline mission mass-budget is as follows: each of the crew-of-four needs about 1.2kg/day of (~0.8 kg respiration consumption + ~0.4 kg leakage make-up) oxygen for 725 days after Mars-touchdown(400 days on Mars and 325 days of Mars-to-Earth return journey in a Hohlmann minimum-energy transit-trajectory) and0.5 kg day of water (for system + pressure-suits leakage make-up, assuming nearly-full water-recycling, includingpartial metabolic water recovery, but with no carbon or nitrogen recycling). The ascent-stage propulsion-plant is takento be RL-10-based, and exhausts a 5:1 (by mass) O2/H2 propellant-mix with a near-vacuum Isp of 490 seconds(expansion ratio of 200:1); it’ll require about 21 tons of this propellant mix to inject an 8-ton return-to-Earth moduleinto a trans-Earth trajectory from the Martian surface. Martian surface exploration is assumed to require another 5 tonsof this propellant-mix to fuel the 0.5 ton (dry-mass + Rover + crew-of-two) Hop-About for ~5 rocket-liftoff / ballisticflight / aerobrake-landing forays to sites roughly equally-spaced all over the Martian surface. These requirementsaggregate to a total post-Mars touchdown mission demand of 24.5 tons of O2, 4.2 tons of H2 and 1.4 tons of H2O perse. This is equivalent to about 39 tons of water, with 10.3 tons of O2 to spare (e.g., for use in Base, pressure suit andRover crew-module leakage make-up, at a mean rate of ~25 kg/day). It’s therefore appropriate to scale the Water Plantto produce 40 tons of water during the 400 day stay-duration, i.e., to average a daily production of 100 kg, or ~1gm/second – all as foreseen above.

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Implications for Manned Mars ExplorationThe present work represents another step down the path charted by Zubrin – with his proposal for a landed methane-generating plant carrying its own liquefied hydrogen feedstock – of innovatively exploiting indigenous Martianresources to drive down the mission-mass cost – and thus the total mission dollar cost – of mounting even the firsthuman expeditions to Mars. Ours is a more ambitious, ‘’philosopher’s stone’’ gambit, which aims at generatingessentially all the consumables ever needed thereafter by the as-landed expedition from readily available localfeedstreams – Martian air and ambient sunlight – with a single Water Plant consisting of a handful of readily-availableor – fabricated components: water-condenser, radiator, water-electrolytic cell, H2/O2 liquefaction unit, cryogen andwater storage-tanks and a photovoltaic array. (We emphasize use of PVA power sources over alternate, e.g., nuclear,ones purely for their current “commercial off-the-shelf”’ availability characteristics.)

The beauty of the present gambit is that it substitutes equipment having about 1% of the mass of the materials generatedfor the far greater mass of the materials themselves. This attractiveness is accentuated by the fact that the thereby-substituted-for mass comprises about 70% of the total leaving-LEO mass-budget of a large set of innovative, aerobrake-intensive architectures for the Mars exploration mission – and 90% of the leaving-LEO mass of conventional initialexploration architectures involving powered descent to the Martian surface. The immediate implication of this is that thelifting-to-LEO challenge for mounting even the first Mars Expedition – one which benefits not-at-all from legacies fromprevious expeditions – can be reduced from a few dozen Shuttle-equivalent payloads to 2 such cargoes, i.e., <50 tons totalmission-mass, staged within a single year. A set of comparable mission mass-budgets for the three basic types of mission-architecture – conventional powered descent to the Martian surface, conventional aerobraked descent and aerobrakeddescent with Water Plant – is shown in Table 1. Figure 2 graphically depicts these basic differences, in a toe-to-toecomparison of two aerobrake-descent Mars manned mission architectures, one with and the other without a Water Plant.

The incremental cost of the lifts-to-LEO required to mount an initial manned expedition to Mars is reduced by WaterPlant usage to ~$100 M, at NASA’s quoted marginal cost of a Shuttle launch of ~$50 M – or a cost of ~$1.1 B, at OMB’sestimated full average operational cost of $550 M for a Shuttle-flight. (Lifting 41 tons of payload into LEO viacommercial space-launch services would entail a present-day cost of ~$450 M, at a cost of $5,000/pound.) The cost ofthe 10 tons of mission hardware, estimated-in-bulk using the usual rule-of-thumb of $10/gm, would be roughly $100 M.RDT&E costs should be (at most) comparable to the purchase-cost of the mission hardware, due to the basic COTScharacter of the materials and equipment chosen, so that total attributable mission costs should aggregate to $300 M -$1.3 B, depending on whose Shuttle-mission cost estimates you prefer to believe – and assuming that 2 Shuttle launchesare employed. Alternatively, the cost of preparing and executing the baseline mission in a purely commercial modewould be ~$650 M – $450 M for the space-launch services procured to lift-to-LEO $100 M of hardware andconsumables, after ground-side RDT&E of $100 M.

The realistic prospect of a Mars Expedition realized at a cost of significantly less than a single year’s Stationconstruction budget of ~$2.5 B is surely one that most reasonable political leaders couldn’t long resist – even in an erawhen the two major political parties effectively differ on civil-space policy only by how much the NASA budget shouldbe cut each year. Moreover, and quite importantly, sponsorship of the first human expedition to Mars thereby is broughtwell within the means of a single exceptionally wealthy individual – this in an era when no one yet lives forever, andmeans of “taking it with you” have yet to be perfected.

Full, innovative exploitation of Martian water thus might be a make-or-break issue for manned Mars exploration thisside of the indefinite future.

Expedited Exploration of the Mid-Solar System: The Jovian and Saturnian SystemsAggressive exploitation of indigenous water resources for realization of life-support and cryogenic propulsive liquidsmay be the key to relatively near-term manned exploration of the Solar system, particularly its “middle” portions, e.g.,out to the Jovian and Saturnian ice-bearing moons. The basic point, of course, is that leaving-LEO mass-budgets foreffectively one-way missions – ones which fully exploit water at their destination-point for life support there, and for

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return-to-Earth propellants – are exponentially smaller than for round-trip ones. Now it is currently unfashionable tosend even volunteers on one-way, i.e., settlement-committed, Government-sponsored space missions, in the manner inwhich the East Coast of the United States was initially settled. Thus, it is necessary at present to consider missionarchitectures that return expedition crews to Earth after comparatively brief stays at their outbound destinations. Thecorresponding Gordian knot may be slashed by equipping expeditions to places such as Ganymede and Europa (and ice-bearing asteroids, and icy Saturian moons, and . . .) with equipment quite similar to the Mars Water Plant which wediscussed above, so that they can re-equip themselves for the return segment of the trip – as well as support their localliving and exploration activities – entirely with products derived from local water at their destinations.

It might appear difficult to photovoltaically energize the equivalent of a Mars Water Plant for a location as distant fromthe Sun as Europa, let alone Titan, simply because the intensity of sunlight is 1-4% of that on Earth at the Saturnian andJovian orbits, respectively, and use of photovoltaic arrays for generation of the required electric power thus wouldappear to be impractical. Actually, this isn’t the case, since direct band-gap semiconductors, e.g., GaAs, are more thantwo orders-of-magnitude more mass-efficient than indirect band-gap ones, such as Si, in photovoltaic conversion, i.e.,= 1 micron thicknesses of GaAs are optically thick to most of the solar spectrum whereas >100 microns is required forequivalent solar-spectrum photo-opacity of Si. Very thin sheets of direct band-gap semiconductor, strengthenedappropriately with an underside polyaramid layer, thus may be expected to provide practical, =1 W/gm specificphotoelectric electric power production as far out as Saturn’s orbit, i.e., in 14 W/m2 sunlight.

A manned mission to Europa is challenged by the nominal 6.3 km/sec trans-Europan insertion delta-V from LEO, whichhas added to it the 6.8 km/s of delta-V required to brake to a soft-landing on the near-vacuum surface of Europa uponentering the Jovian system on a Hohmann transfer trajectory. Even the use of RL-10-based propulsion systems, withtheir restartability and their 4.9 km/s exhaust speeds, seemingly implies mass-ratios of 14.5 for such one-way missions.Actually, a Minovitch (gravity-assisted) Earth-Venus-Jupiter trajectory can reduce the outbound insertion delta-V to 4.4km/s without a significant increase in outbound trip-time and a Jovian-system capture-burn at Io’s depth in the Joviangravity-well, followed by more Minovitch maneuvering among the Galilean moons before a powered touchdown onEuropa can trim the total circum-Jove maneuvering delta-V to 5.1 km/s. The total outbound mission delta-V can bethereby reduced to no more than 9.5 km/s. This, in turn, implies a Rocket Equation multiplier of 6.95 on the leaving-LEO mission-payload mass of ~25 tons (corresponding to a total mission-time of about 7 years, including a year on theEuropan surface), so that the reference Europan expedition’s total leaving-LEO mass is only 173 tons. The numbers fora crew-of-four expedition to Callisto or Ganymede are essentially the same. (Of course, the same expedition might careto average down its outbound-and-return “travel overheads,” and touchdown successively on more than one icy Galileanmoon, “while in the neighborhood,” refueling at each stop.)

The corresponding leaving-LEO delta-V on a Minovitch trajectory to Titan is only 4.7 km/s (!), reasonably assuminguse of aerobraking for a Titan touchdown (although use of highly mass-economized photovoltaic arrays on the Titaniansurface, where wind momentum flux densities might be quite large, cannot be assured until confirming meteorologicaldata, e.g., from the Huygens probe of Cassini, is in-hand). Soft-landing on a vacuum-shrouded, ice-bearing Saturnianmoon naturally would be significantly more expensive in delta-V, unless the first stop in the Saturnian system were madeat Titan, thereby sinking the interplanetary delta-V. In this case, refueling could be done first at Titan, and then the tankscould be “topped off” as indicated at successive stops on other icy-albeit-vacuum-shrouded Saturnian moons prior toEarth-return from the final one of them. The corresponding Rocket Equation multiplier for the Titan expedition is(only!) 2.6 on a characteristic Saturnian mission-payload mass of ~40 tons, so that the leaving-LEO mass for a mannedexpedition to the surface of Titan is (only) 104 tons! The total mission time would be about 14 years; assuming 1.5 yearswere spent on the surface of Titan (as well as skipping among the icy Saturnian moons). In both the Europa and Titanexpedition cases, the total impulse required for lift-off of the surface and insertion into a trans-Earth trajectory isn’tlarger than the total outbound impulse, so that propellant tankage reuse is entirely feasible: the expedition’s transit-vehicle touches down at the icy destination with dry cryopropellant (and water, and oxygen) tanks and lifts off with (inthe case of cryopropellants, partly-) full ones reloaded with local water products. These Jovian and Saturnian systemexploration data are summarized in Table 2, along with those of the baseline case for Mars.

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These relatively very modest leaving-LEO masses for round-trip manned expeditions to Solar system destinationshitherto considered to be unattainably distant relative to contemporary human technology should motivate seriousthought about mounting such expeditions during the next few minimum-energy “launch windows.” That most all of theleaving-LEO mass in all of these cases is comprised of water products – LH2 and LO2 – and thus of material which maybe Earth-orbited in convenient-sized parcels with high-acceleration, potentially low-cost means, should be especiallythought provoking.

Moving Out From HereWhat’s a reasonable path to follow along the lines just sketched, leading from the present to a first crew return from theRed Planet – or to launching of an manned expedition to the Jovian or Saturnian systems?

It might be reasonable to first design, then to prototype in sub-scale, and then to build in full-scale such a Water Plantfor Earth-side evaluation. Such evaluation presumably would culminate in an environmental chamber that duplicatesthe key features of the Martian surface, atmosphere and sky – and likely would involve a Water Plant implemented insomething like 1% of full scale, i.e., a 1-meter scale-size, producing 1 liter/day of water. Once the basic design hadthereby been qualified and a full-scale one had been deployed satisfactorily in Earth-surface simulation from an as-landed package, it would be appropriate to send the full-scale system to Mars for real field trials. Even the first suchtrial could lay the Martian logistics foundation for a follow-on manned expedition in the next launch window 25 monthsthereafter, if it were adequately successful.

It’s readily feasible to send a full-scale Water Plant of the type sketched above to the Martian surface on a single Atlas-Centaur-class launch inserting an aerobraked descent package into trans-Mars orbit, to deploy it and put it into operationrobotically once it’s landed, and then to operate it until its water and cryogenic propellant tanks all are full. A mannedexpedition, perhaps carrying a back-up Water Plant as well as a Mars Greenhouse, could thereafter leave for Mars in afar smaller – and corresponding less expensive – total mission-package than any currently contemplated.

A program of this type seemingly would fit aptly within a NASA Discovery programmatic time-and-dollar envelope –if it were planned and executed in a thoroughly competent and reasonably innovative manner (e.g., involvingcollaborations between major technical universities and aerospace primes). As such, it would constitute a notably low-cost, short execution-time technology-demonstrator and mission-enabler of remarkably large proportions for the firstmanned expedition to Mars.

Eventually, sustained-and-concatenated exercising of human ingenuity will reduce the cost of a first human expeditionto Mars – and to the icy Jovian and Saturnian Moons – to levels such that even non-governmental resources will sufficereadily to sponsor it. We offer the Martian Water Plant sketched in the foregoing as a stone for use in raising this greatedifice of technology-and-intellect, moreover in our time.

AcknowledgmentsWe thank our many colleagues who have discussed with us over the past third-century various aspects of the mannedexploration and settlement of Mars; we regret not being able to acknowledge them individually. No claim is made fororiginality, either of the basic concepts or the specific technological approaches, discussed in the foregoing, any numberof which may have been anticipated by others unknown to us.

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Tables

Table 1. Comparable Mass Budgets For Three Manned Mars Missions

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Table 2. Mission Parameters For Manned Expeditions “Watering” At The Destinations

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Figures

Figure 1. Water content of the Martian surface-level atmosphere versus time in Martian days (Sols) measuredindirectly by the Viking Lander 1 (VL1) and Viking Lander 2 (VL2). The VL1 data-set is significant more consistentwith other measurements of Martian atmospheric water content, and thus is used as the basis for the calculatedseasonal variation of the inferred globally-averaged atmospheric water content, which is labeled ‘New Houston.’

The globally- and seasonally-averaged single-value is labeled ‘Global Average.’ [After Grover and Bruckner, “WaterVapor Extraction from the Martian Atmosphere by Adsorption in Molecular Sieves,” AIAA Paper 98-3302 (1998).]The vertical right axis indicates the temperature at which the water vapor content on the left vertical axis is the

saturation vapor pressure, i.e., below which temperature water vapor will condense from the air.

Figure 2. A diagrammatic representation of the major components of the Water Plant.

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Figure 3. The time-evolution of the mass budgets of two manned expeditions to Mars consisting of a crew-of-four, whichstays on Mars the 400-day fraction of the synodic period corresponding to minimum-energy trajectories from Earth-to-Mars

and then from Mars-to-Earth. [After Hyde, Ishikawa & Wood, “The GREAT EXPLORATION Plan For The Human SpaceExploration Initiative,” UCLLNL PHYS-BRIEF 90-402 (1990).] The “No Martian Water Usage” mission-architecture is a ‘neo-

classical’ one which aerobrakes the Mars landing-package but brings all mission-required consumables from the Earth,and is the second of the three cases of Table I. The “Martian Water Exploitation” mission-architecture fully exploits Martianatmospheric water via a Water Plant of the type discussed in the text, and thus is the third, “baseline” case of Table I, andthereby realizes = 3-fold savings in the leaving-LEO mass-budget, relative to the mission involving no Martian water exp-

loitation. The “wet Mars” mission-architecture also readily extends to include a flex-walled Mars Greenhouse of 2 ton/500 m2-scale, the principal item in whose in-use mass-budget is Martian water, in =10 kg/m2 - illuminated specific

quantities; manned Mars expeditions of indefinitely great duration and self-sufficient Martian settlements are thereby enabled.

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Figure 4. An artist’s conception of the two primary types of Mars surface-exploration vehicles. A RL-10-based rocketpropulsion unit – dubbed a ‘Hop-About’– is used for launching into a ballistic trajectory – aerobraked at its terminus– a pair of expedition crew-members enclosed in a flex-walled cabin and a Mars Rover (a technological descendent

of the Apollo Lunar Rover) from the expedition’s Mars Base to any other site on the Red Planet. At any such secondaryexploration site, the H2/O2 fuel-cell-powered Rover is roll-on / roll-off-deployed from its stowage-point on the Hop-Aboutto carry the crew-pair and their light equipment around for local exploration, sample-gathering, etc.; the return-to-Base

flight has the same characteristics as did the outbound one. [After Hyde, Ishikawa & Wood, “The GREAT EXPLORATIONPlan For The Human Space Exploration Initiative,” UCLLNL PHYS-BRIEF 90-402 (1990).] All of the consumables of theexploration transportation system – propulsive mass, H2/O2 fuel-cell feedstreams and all life-support fluids – are derivedfrom Martian atmospheric water via the Water Plant discussed in the text, so that such intensive all-planet exploration,

even on the first manned Mars mission, is cost-free with respect to all consumables.

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Documents

2001Mars Society Convention Part 5