Space elevator REPORT

SPACE ELEVATOR.

1. INTRODUCTION1.1. What is space elevator?

A Space Elevator? Even though the space elevator has made several appearances in

science fiction, few people are familiar with the concept. In the most basic description

the space elevator is a cable with one end attached to the Earth and the other end roughly

60,000 miles out in space (see figure). Standing on the Earth at the base of this

“beanstalk” it would look unusual but simple, a cable attached to the ground and going

straight up out of sight. Now even the youngest of you reading this manuscript will know

that a rope cannot simply hang in mid-air, it will fall. This is true in all of our everyday

situations; however, a 60,000-mile long cable sticking up into space is not an everyday

occurrence. This particular cable will hang in space, stationary and tight. The difference

between why a 10-ft piece of rope will fall and a 60,000-mile long cable will not has to

do with the fact that the Earth is spinning. The cable for the space elevator is long

enough that the spinning of the Earth will sling it outward, keeping it tight. The 10 ft.

length of rope is too short to really feel this effect. To illustrate what I mean, let me give

an example. If you take a string with a ball on the end and quickly swing it around your

head the string sticks straight out and the ball doesn’t fall. Now imagine that string is

60,000 miles long and your hand holding the string is the Earth. The two situations, the

ball swinging around your head and the space elevator swinging around the Earth, are

really quite similar. Okay, great, so we now have a cable pointing straight up into space,

so what. The so what part is that it is possible to climb this cable from Earth to space,

quickly, easily, and inexpensively. Travel to space and the other planets will become

simple if not routine. That all sounds straightforward doesn’t it? The 60,000 mile part

may give some of you pause but trust me man has built much more massive and more

complicated structures than what we will be discussing. This one is just in a particularly

unique shape and location. With that said I hope you will also trust me and believe that

building and using a space elevator is not nearly as simple as I have explained so far. I

have left out a few details, thus the rest of this manuscript. I should also state right at the

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offset that this manuscript is an extension of a paper I put together that will be published

1. Space Elevator

Any time now in Acta Astronautica[Edwards, 2000]. The concept is the same but this

study has modified many of the details found in the Acta Astronautica paper The concept

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of a space elevator first came from an inventive Russian at the dawn of the space age but

the appearances of the space elevator I enjoy most came in several science fiction books.

However, I would consider this method as too expensive and too difficult to be a viable

option outside of science fiction. The capture and movement of an asteroid, though not

impossible, would be extremely challenging. In addition, the operations that would be

required at very high Earth orbit (mining and cable fabrication) are also beyond what I

would consider economically feasible at this time. I may be wrong on both of these

but…well, allow me to continue. Outside of science fiction there was some work done on

the space elevator during the first decades of the space age . But even in the past few

years the space elevator concept has often been discarded out-of-hand as inconceivable or

at least inconceivable for the next century. The reason for the general pessimism was that

no material in existence was strong enough to build the cable. We have a serious canyon

and the string is longer but the concept is the same. First, a satellite is sent up and it

deploys a small “string” back down to Earth. To this string we attach a climber which

ascends it to orbit. While the climber is ascending the “string” it is attaching a second

string alongside the first to make it stronger. This process is repeated with progressively

larger climbers until the “string” has been thickened to a cable, our space elevator. That’s

a pretty simple breakdown of what we are considering, allow me to add a few more

details. In considering the deployment of a space elevator we can break the problem into

three largely independent stages: 1) Deploy a minimal cable, 2) Increase this minimal

cable to a useful capability, and 3) Utilize the cable for accessing space. The initial

“string” we deploy from orbit is actually a ribbon about 1 micron (0.00004 inches) thick,

tapering from 5 cm (2 inches) at the Earth to 11.5 cm (4.5 inches) wide near the middle

and has a total length of 55,000 miles (91,000 km). This ribbon cable and a couple large

upper stage rockets will be loaded on to a handful of shuttles (7) and placed in low-Earth

orbit. Once assembled in orbit the upper stage rockets will be used to take the cable up to

geosynchronous orbitB&D where it will be deployed. As the spacecraft deploys the cable

downward the spacecraft will be moved outward to a higher orbit to keep it stationary

above a point on Earth (a bit of physics we will explain later).

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2. NEED OF SPACE ELEVATOR

2.1. Why would we want to build a space elevator?

Our society has changed dramatically in the last few decades from the first transistor to

the internet, DVD’s and supercomputer laptops, from propeller airplanes to men on the

moon, from hybrid plants to mapping human DNA. Often great advances in our society

take a single, seemingly small step as a catalyst to start a cascade of progress. And just as

often the cascade of progress is barely imagined when that first small step is taken. The

space elevator could be a catalytic step in our history. We can speculate on many of the

things that will result from construction of a space elevator but the reality of it will

probably be much more. At the moment we can at best speculate on the near-term returns

of a space elevator. To make a good estimate of the returns we can expect we need to

know where we are now, how the situation will change if we have an operational space

elevator and what new possibilities this change will cultivate. First, where we are now:

• Getting to space is very expensive: millions for the launch of a small payload to low

Earth orbit, $400 million in launch costs to get a satellite to geosynchronous orbit and

possibly trillions for a manned Mars exploration program.

• Operating in space is risky. There are few situations where repair of broken hardware is

possible and believe me launch shocks do break hardware.

• Because of the limited, expensive access to space and the risk involved in space

operations the satellites placed in space are also expensive and complex

• It is difficult to bring things back down from space. The only real exception to this is

the space shuttle.

• Neither the government nor the public accepts failure well in the space program.

That’s the current situation. The next thing we need to know is how the situation will

change if we have an operational space elevator. The space elevator will be able to:

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• Place heavy and fragile payloads in any Earth orbit (with a circularizing rocket) or send

them to other planets.

• Deliver payloads with minimal vibration.

• Bring heavy and fragile payloads down from space.

• Deliver payloads to space at a small fraction of current costs.

• Send a payload into space or receive a payload from space every few days.

• Be used to quickly produce additional cables or increase its own capacity.

• Survive problems and failures and be repaired.

Having an operating space elevator would dramatically change our ‘reality’ picture of

space operations as we described above. With this new set of parameters for space

operations and the same economic reality we live in, we could reasonably expect the

following in roughly chronological order:

• Inexpensive delivery of satellites to space at 50% to possibly 99% reduction in cost

depending on the satellite and orbit. This would allow for more companies and countries

to access space and benefit from that access.

• Recovery and repair of malfunctioning spacecraft’s. Telecommunications companies

could fix minor problems on large satellites instead of replacing the entire spacecraft.

• Large-scale commercial manufacturing in microgravity space. Higher quality materials

and crystals could be manufactured allowing for improvements in everything from

medicine to computer chips.

• Inexpensive global satellite systems. Global telephone and television systems would

become much easier and less expensive to set-up. Local calls could be to anyplace but

maybe Mars (at least initially).

• Sensitive global monitoring of the Earth and its environment with much larger and more

powerful satellites. Extensive observing systems could be implemented to truly

understand what we are doing to our environment.

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.3. SPACE ELEVATOR DEVELOPMENT

3.1. Major Elements are

3.1.1. Ribbon Tether-

A space elevator tether must be made of a material that can withstand both its

environment and operational stresses. A feasibility condition is identified which

establishes goals for the tether material. Materials currently being tested in the laboratory

have surpassed that level and promise a tether that can withstand the environmental and

operational stresses necessary

Will be made of 22,000 mile long carbon nanotube strands because it is currently

the only option which has the proper strength and is light enough

Will need to be wider at geosynchronous altitude where it will experience the

most stress and taper down as it approaches earth

It is a light, flexible, ultra strong metal that robots can grip with their climbing

treads.

It act as a guide rail for the climber

It is a long ribbon of carbon nanotubes that would be wound into a spool that

would be launched into the orbit.

When the spacecraft carrying the spool reaches a certain altitude, perhaps Low

Earth Orbit, it would begin unspooling, lowering the ribbon back to Earth.

At the same time, the spool would continue moving to a higher altitude. When the

ribbon is lowered into Earth's atmosphere, it would be caught and then lowered

and anchored to a mobile platform in the ocean.

The cable must be made of a material with a large tensile strength/density ratio

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2 Carbon Nanotube Structure

3.1.2. The Anchor (End Station Infrastructure of base)-

Anchor station is a mobile, oceangoing platform identical to ones used in oil drilling

anchor is located in eastern equatorial pacific, weather and mobility are primary factors

a) The space anchor will consist of the spent launch vehicle

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b) The Earth anchor will consist of a mobile sea platform 1500 miles from the

Galapagos islands

c) Anchor station is a mobile, ocean-going platform identical to ones used in oil

drilling

d) Anchor is located in eastern equatorial pacific

e) Weather and mobility are primary factors

3. Anchor

3.1.3. Spacecraft and Climber-

Climbers built with current satellite technology

Drive system built with DC electric motors

Photovoltaic array (GaAs or Si) receives power from Earth

7-ton climbers carry 13-ton payloads

Climbers ascend at 200 km/hr.

8 day trip from Earth to geosynchronous altitude

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It will be powered by lasers and solar power

It is estimated that the climb will take about 5 days

Initial ~200 climbers used to build Nano-ribbon

4. Basic Diagrams Climber

Later used as launch vehicles for payloads from 20,000- 1,000,000 kg, at

velocities up to 200km/hr.

Climbers powered by electron laser & photovoltaic cells, with power

requirements of 1.4-120MW

Climbers built with current satellite technology

Drive system built with DC electric motors

Photovoltaic array (GaAs or Si) receives power from Earth

7-ton climbers carry 13-ton payloads

Climbers ascend at 200 km/hr.

8 day trip from Earth to geosynchronous altitude

Initial 200 climbers used to build ribbon

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5. Space Craft and Climber

3.1.4. Power System-

Power is sent to deployment spacecraft and climbers by laser

Solid-state disk laser produces kWs of power and being developed for MWatts

Various methods proposed to get the energy to the climber are:

Transfer the energy to the climber through wireless energy transfer while it is

climbing.

Transfer the energy to the climber through some material structure

Store the energy in the climber before it starts – requires an extremely

high specific energy such as nuclear energy.

Solar power – power compared to the weight of panels limits the speed of climb.

Wireless energy system involves:

The lifter will be powered by a free-electron laser system located on or near the

anchor station

It requires physical installations at the transmitting and receiving points, and

nothing in between.

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6. Power System

3.1.5. Counter Weight (End Station Infrastructure of Apex Anchor)

• Captured asteroid, Space station above geostationary orbit Capture an asteroid

and bring into Earth orbit

• Mine the asteroid for carbon and extrude 10m diameter cable

• Asteroid becomes counterweight

7. Counter Weight


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4. CABLE DESIGN AND PRODUCTION

4.1. For cable design we use carbon nanotube (CNTs)

In 1991 the first carbon nanotubes were made .These structures

have promise of being the strongest material yet discovered. This strength combined

with the low density of the material makes it critically important when considering

the design of a space elevator. The tensile strength of carbon nanotubes has been

theorized and simulated to be 130 GPaB&D compared to steel at <5 GPa and Kevlar

at 3.6 GPa. The density of the carbon nanotubes (1300 kg/m3) is also lower than

either steel (7900 kg/m3) or Kevlar (1440 kg/m3). The critical importance of these

properties is seen in that the taper ratio of the cable is extremely dependent on the

strength to weight ratio of the material used. A taper in the cable is required to

provide the necessary support strength

4.1.1. What is a Carbon Nanotube?

Can be thought of as a sheet of graphite (a hexagonal lattice of

carbon) rolled into a cylinder.

4.1.2. Why Carbon Nanotubes (CNTs)?

Young's modulus is over 1 Tera Pascal and Strength 100x that of

steel at 1/6 the weight (estimated tensile strength is 200 Giga Pascal) .There are some

properties of carbon nanotubes which proves that why carbon nanotube is used to build

Ribbon tether


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Properties of single wall nanotubes:-

1. Tensile strength is 45 billion Pascal

2. Resilience can be bend at large angle and re-straightened without damage

3. Temperature stability of carbon nanotube is stable upto 2800 degree in

vacuum,750 degrees in air

Properties of metal wire:-

1. Tensile strength is high strength steel alloys break at 2 billion

2. Resilience of metal wire and carbon fibers fracture at grain boundaries

3. Temperature stability of metal wire in microchips melt at 600 to 1000 degrees

Celsius


SPACE ELEVATOR.

5. HISTORY

1960: Artsutanov, a Russian scientist first suggests the concept in a journal

1966-1975: In 1966, Isaacs, Vine, Bradner and Bachus, reinvented the concept, naming it

a "Sky-Hook," and published their analysis in the journal Science calculating specifics of

what would be required

1979: Author Clarke, in Fountains of Paradise describes the concept

1999: NASA holds first workshop on space elevators after the discovery of carbon

nanotubes.

2001: Bradley Edwards receives NAIC funding for Phase I space elevator mock-up

2005: Lift Port Group announced that it will be building a carbon nanotube

manufacturing plant in Millville, New Jersey,

2011: Google was revealed to be working on plans for a space elevator at its

secretive Google X Lab.

2006: Lift Port Group announced that they had tested a mile of "space-elevator tether"

made of carbon-fiber composite strings and fiberglass tape measuring 5 cm (2 in) wide

and 1 mm (approx. 13 sheets of paper) thick, lifted with balloons

2012: Obayashi Corporation announced that by 2050 it could build a space elevator using

carbon nanotube technology

• It originated with the famous Russian scientist Konstantin Tsiolkovsky (known

for pioneering rocketry ideas) who thought of a ”Celestial Castle” in

geosynchronous Earth orbit attached to a tower on the ground.

• Later a Leningrad engineer by the name of Yuri Artsutanov wrote some of the

first modern ideas about space elevators in 1960 in the Soviet newspaper Pravda.

But this paper was the o fical newspaper of the communist party and thus was offfi

course not read by anyone, so the idea did not gain wider recognition.


SPACE ELEVATOR.

• The popularization of the idea started, though, with the 1975 paper by Pearson,

who not only did the basic strength calculation but also considered several

complications and how it might be built [Pearson, Acta Astronautica 2 (1975)

785-799]. Inspired by this in 1978 Arthur C. Clarke popularized it to a wider

audience in his 1978 science fiction novel, “Fountains of Paradise”.

• If realized, it would allow for putting up a passenger with baggage to space for

something like 200 USD - so it really would revolutionize space travel

• During the 3rd annual Space Elevator Conference in Washington, D.C. George

Whiteside’s (Whiteside’s, 2004) stated:

• “Until you build an infrastructure, you are not serious.”

8. Space Station


SPACE ELEVATOR.

6. CHALLENGES

The major challenges faced for bringing this concept in reality are:-

Atmospheric issues

Lightening, clouds, winds. Historic data maps shows lightening occurs a land masses ,les

s on mountains and least along equator,

further experimental cables don't attract lightening ,winds aren't a factor since it is capabl

e of withstanding wind spend of 71m/hr

and hurricanes not a problem since they form and travel outside the equatorial region.

Impact or Collision

Big issues requiring more study .Debris is monitored using radar. Stud between Debris an

d meteors indicate space debris to be

more hazardous .It must be noted number of impacts on ribbon, not as important as degra

dation cost due to impact.

Health issues

Fiber health focuses on three things, dose, dimension and durability .The bigger ones can'

t be integrated and smaller ones appear to dissolve quickly

• Will require a strong material such as carbon nanotubes which we don’t currently

possess the ability to form into a long enough tether

• Will the public be convinced it is a good idea

• Continuation of tether technology development to gain experience in the

deployment and control of such long structures in space.

• The introduction of lightweight, composite structural materials to the general

construction industry for the development of taller towers and buildings

• The development of high-speed, electromagnetic [maglev] propulsion for mass-

Transportation systems, launch systems, launch assist systems and high-velocity

launch rails. These are, basically, higher speed versions of the trams now used at

airports to carry passengers between terminals.


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“The development of transportation, utility and facility infrastructures to support

9. Environmental Effect


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7. ADVANTAGES AND DISADVANTAGES

7.1. ADVANTAGES:-

1. Low operations costs -US$250/kg to LEO, GEO, Moon, Mars, Venus or the asteroid

belts

2. No payload envelope restrictions

3. No launch vibrations

4. Safe access to space -no explosive propellants or dangerous launch or re-entry forces

5.Easily expandable to large systems or multiple systems

6. Easily implemented at many solar system locations

7.2. DISADVANTAGES:-

1. The entire structure is massive.

2. High cost and require much time for construction.

3. Still there is challenge to build long nanotube because That the single tubes are

relatively short

4. Small mistake can be harmful to the human during developing space elevator

5. it will required man power and it should require more skill to work space orbit or

survive in space orbit


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8. FEATURE SCOPE:- Solar power satellites - economical, clean power for use on Earth

Solar System Exploration - colonization and full development of the moon, Mars

and Earth orbit

Telecommunications - enables extremely high performance systems

As of 2004, carbon nanotubes are more expensive than gold. Future supply

increase will lower this price

Technology to “spin” Van der Waal bonded Nano-yarn has begun.

Edwards completed Phase II planning in 2004, with funding from NASA’s

institute for advanced concepts

However, many properties of nanotubes still remain to be tested, frictional,

collisional, etc.

Third Space Elevator Conference is held to discuss advances on the concept

Fully operational elevator could be built within 15 years.

10. Solar Power satellite


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9. CONCLUSION

The space elevator is a revolutionary Earth-to-space transportation system that will

enable space exploration. Development of the space elevator requires an investment in

materials and engineering but is achievable in the near future with a reasonable

investment and development plan. The future of space travel. Would set us on the path

towards expanding our space exploration to places might never reach relying solely on

rockets. Philip Ragan, co-author of the book "Leaving the Planet by Space Elevator",

states that "The first country to deploy a space elevator will have a 95 percent cost

advantage and could potentially control all space activities." The space elevator has

tremendous potential for improving access to Earth orbit, space and the other planets.

This will help to build strong science which will increase technology growth in all

nations. Due to lack of viable material and lack of support space elevator is still in

working .Aim is to create space elevator as a “free” system


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REFERENCES

1. Artsutanov, Y. “Into the Cosmos by Electric Rocket”, Komsomolskaya Pravda, 31 July 1960. (The contents are described in English by Lvov in Science, 158, 946-947, 1967.)

2. Artsutanov, Y. “Into the Cosmos without Rockets”, Znanije-Sila 7, 25, 1969.3. Pearson, J. “The Orbital Tower: A Spacecraft Launcher Using the Earth's

Rotational Energy”, Acta Astronautica 2, 785-799, 1975. 4. Edwards, B. C.; Westling, E. A. “The Space Elevator: A Revolutionary Earth-

to-Space Transportation System”, ISBN 0972604502, published by the authors, January 2003s

5. Mason, L. S. “A Solar Dynamic Power Option for Space Solar Power”, Technical Memorandum NASA/TM— 1999-209380 SAE 99–01–2601, 1999

6. Wyrsch, N. & 8 co-authors (2006) “Ultra-Light Amorphous Silicon Cell for Space Applications," Presented at 4th World Conference and Exhibition on Photovoltaic Solar Energy Conversion, March 2006, Waikoloa, Hawaii [


Engineering

Space elevator REPORT