11.5.1 SOLAR PARTICLE EVENTS - NASA · By presenting a single benchmark definition of natural environment ... Branch with the concurrence of the Office of the ESMD Chief Engineer

Lunar Natural Environment for Use by the Constellation Programby

Dale C. FergusonNASA Marshall Space Flight Center

The Lunar Environments used by the Constellation Program are embodied in twodocuments, the NEDD (Natural Environments Definition for Design) and the DSNE(Design Specification for Natural Environments). Recently, the lunar environments forthe NEDD have been defined and incorporated in the document, as the result ofcontributions from experts in all areas of lunar environments. The purpose of the NEDDis to provide a uniform description of the natural environment to serve as a basicframework for both the crewed and robotic missions of the Exploration Systems MissionDirectorate (ESMD). It is intended to support engineering and analysis, requirementsdevelopment, and verification involved in the development of exploration concepts andarchitectures, flight hardware, and new technologies. (It does not support the operationalphases of the Program since models and data with different properties are needed forthose applications.) By presenting a single benchmark definition of natural environmentparameters it provides an easily accessible and uniform baseline for competitive studies,independent analyses, and concept studies. This document is a requirement in the sensethat its use is directed by the Program, but it does not contain any requirement “shall”language. It provides a single description of each environment that requirements may bewritten against, thereby enabling clear definition of contract scope and control. Byproviding a complete and single source for environment data, the document also reducessystem development cost by providing a ready source of required technical data andminimizing the environment related efforts required of the contractor community. Sincethe definitions specified herein are, for the most part, definitions developed and used onprior programs, they are well understood by NASA and significant portions of thecontractor community. Thus, use of this book enables a better understanding of Programtechnical risk than would be possible without a baselined definition document.

The scope of the NEDD lunar sections is described below:

Natural environment, as the term is used here, is intended to include allenvironmental factors, which are independent, i.e., outside the influence, of theProgram. Orbital debris and some other man-made environments are includedbecause they are beyond Program control. All induced environments,contamination, and aeroheating, for example, are excluded because they aredependent on system design. Likewise, “environmental impact,” the effects of theProgram on the environment, is not within this scope. This document is providedin four main sections, which between them, are intended to include all naturalenvironments needed to support aerospace vehicle design and developmentactivities. The material is divided as follows:

a. Terrestrial Environments (Sections 2 through 4)b. Near-Earth Space Environments (Sections 6 through 8)c. Cis-Lunar and Lunar Environments (Sections 10 through 13)d. Mars and Mars Transit Environments (Sections 16 through 21)

https://ntrs.nasa.gov/search.jsp?R=20090017787 2020-05-20T13:38:09+00:00Z

Cis-Lunar and Lunar Environments focus on the lunar orbital and surfaceenvironments.

The NEDD is a handbook and source document for the environment models and dataneeded to support the Program throughout the development phase. It is not a science text.The intent is to provide a useful tool to the Program and the engineering community.When environment information is needed that has not been provided in this document theNatural Environments Branch, Marshall Space Flight Center (MSFC), Alabama, shouldbe notified. They will work via approved Program channels to provide the informationand update this document as appropriate. Clarification and interpretation of theinformation contained herein is also the responsibility of the Natural EnvironmentsBranch with the concurrence of the Office of the ESMD Chief Engineer. The applicationof the models and data provided herein, and documentation of the applications, is theresponsibility of the user. All Constellation-owned software, including models,simulations, and datasets, use CxP 70065, Constellation Program Computing SystemRequirements Document, and CxP 70075, Constellation Program Modeling andSimulation Support Plan (SRR Version) for the development, maintenance, andconfiguration control. Environmental monitoring, forecasting technologies, and models tosupport the operational phase of the Program must be developed as part of the programarchitecture. This document supports the design and development phases only.

Table of Contents for NEDD Lunar Sections:

10.0 CIS-LUNAR AND LUNAR ENVIRONMENTS10.1 INTRODUCTION10.2 ACRONYMS AND ABBREVIATIONS10.3 REFERENCE DOCUMENTS11.0 CIS-LUNAR SPACE (10 TO 60 Re)11.1 RESERVED (NEUTRAL GAS OR PARTICULATES)

11.1.1 Lunar Exosphere (Lunar Atmosphere)11.2 THERMAL ENVIRONMENT11.3 SOLAR WIND (INTERPLANETARY FIELDS)11.4 PLASMA ENVIRONMENTS

11.4.1 Solar Wind11.4.2 Magnetosheath and Magnetotail11.4.3 Extreme Electron Flux Environment for Internal (Bulk) ChargingEvaluations

11.5 IONIZING RADIATION11.5.1 SOLAR PARTICLE EVENTS11.5.2 Galactic Cosmic Radiation11.5.3 Total Ionizing Dose11.5.4 Single Event Effects

11.6 METEOROID ENVIRONMENT12.0 LUNAR SPACE ENVIRONMENT12.1 THERMAL ENVIRONMENT

12.1.1 Solar Constant

12.1.2 Albedo12.1.3 Lunar Long-Wave Radiance

12.2 PLASMA12.2.1 Lunar Plasma (Solar Wind, Magnetosheath, and Magnetotail)Environments12.2.2 Lunar Wake Plasma12.2.3 Plasma Wake Characteristics12.2.4 Plasma Interactions and Effects

12.3 IONIZING RADIATION12.3.1 Solar Particle Events (SPEs)12.3.2 Galactic Cosmic Radiation (GCR)12.3.3 Total Ionizing Dose (TID)12.3.4 Single Event Effects (SEE)

12.4 METEOROID ENVIRONMENT12.5 LUNAR GRAVITY

12.5.1 Lunar Gravity Design Model13.0 LUNAR SURFACE ENVIRONMENTS13.1 PRINCIPAL SURFACE FEATURES; LUNAR HIGHLANDS13.2 PRINCIPAL SURFACE FEATURES; MARIA13.3 REGOLITH COMPOSITION AND CHARACTERISTICS13.4 SURFACE PHYSICAL CHARACTERISTICS13.5 LUNAR DUST13.6 THERMAL ENVIRONMENT13.7 IONIZING RADIATION

13.7.1 Solar Particle Events (SPEs)13.7.2 Galactic Cosmic Radiation (GCR)13.7.3 Lunar Neutron Environment13.7.4 Total Ionizing Dose (TID)13.7.5 Single Event Effects (SEEs)

13.8 METEOROID ENVIRONMENT13.8.1 Flux13.8.2 Lunar Shielding13.8.3 Density13.8.4 Speed13.8.5 Meteor Showers13.8.6 Lunar Secondaries

Overall Lunar NEDD Editor – Dale Ferguson, MSFCNEDD Book Manager – Leigh Smith, MSFCLunar NEDD Writing Team Leads:

Plasma Interactions, Vehicle ChargingDale Ferguson, MSFC

Radiation Environment, Secondary RadiationJoe Minow, MSFC

ContaminationJoey Norwood, MSFC

Lunar Regolith Mechanical PropertiesPaul Greenberg, GRC

Lunar Regolith Electrical Properties, Dust ChargingJason Vaughn, MSFC

Lunar Regolith Chemical and Magnetic PropertiesJim Gaier, GRC

MeteoroidsBill Cooke, MSFC

In this paper, we give examples of some of the lunar sections of the NEDD, showing thetype of content that is present, with particular emphasis on the lunar dust, plasma andcharging environments.

American Institute of Aeronautics and Astronautics

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Lunar Natural Environment for Use by the Constellation Program

Dale C. Ferguson1 NASA Marshall Space Flight Center, Huntsville, AL, 35812

The Lunar Environments used by the Constellation Program are embodied in two documents, the NEDD (Natural Environments Definition for Design) and the DSNE (Design Specification for Natural Environments). Recently, the lunar environments for the NEDD have been defined and incorporated in the document, as the result of contributions from experts in all areas of lunar environments. The purpose of the NEDD is to provide a uniform description of the natural environment to serve as a basic framework for both the crewed and robotic missions of the Exploration Systems Mission Directorate (ESMD). It is intended to support engineering and analysis, requirements development, and verification involved in the development of exploration concepts and architectures, flight hardware, and new technologies. (It does not support the operational phases of the Program since models and data with different properties are needed for those applications.) By presenting a single benchmark definition of natural environment parameters it provides an easily accessible and uniform baseline for competitive studies, independent analyses, and concept studies.

Nomenclature ALSEP = Apollo Lunar Surface Experiment Package CxP = Constellation Program DSNE = Design Specification for Natural Environments ESD = electrostatic discharge ESMD = Exploration Systems Mission Directorate eV = electron volts LEAM = Lunar Ejecta and Meteorite experiment NASA = National Aeronautics and Space Administration NEDD = Natural Environments Definition for Design Introduction nm = nanometers Re = Earth radii SIG = Systems Integration Group S/m = Sieverts per meter SRR = Systems Requirements Review UV = Ultraviolet

HE Lunar Environments used by the Constellation Program are embodied in two documents, the NEDD (Natural Environments Definition for Design) and the DSNE (Design Specification for Natural Environments).

Recently, the lunar environments for the NEDD have been defined and incorporated in the document, as the result of contributions from experts in all areas of lunar environments. The purpose of the NEDD is to provide a uniform description of the natural environment to serve as a basic framework for both the crewed and robotic missions of the Exploration Systems Mission Directorate (ESMD). It is intended to support engineering and analysis, requirements development, and verification involved in the development of exploration concepts and architectures, flight hardware, and new technologies. (It does not support the operational phases of the Program since models and data with different properties are needed for those applications.) By presenting a single benchmark definition of natural environment parameters it provides an easily accessible and uniform baseline for competitive studies, independent analyses, and concept studies. This document is a requirement in the sense that its use is directed by the Program, but it does not contain any requirement “shall” language. It provides a single description of each environment that requirements may be written against, thereby enabling clear definition of contract scope and control. By providing a complete and single source for environment data, the document also reduces system development cost by providing a ready source of required technical data and minimizing the environment related efforts required of the contractor 1 CxP Test and Verification Lead, Environments and Constraints SIG, MSFC EM50, AIAA Senior Member.

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community. Since the definitions specified therein are, for the most part, definitions developed and used on prior programs, they are well understood by NASA and significant portions of the contractor community. Thus, use of the NEDD enables a better understanding of Program technical risk than would be possible without a baselined definition document.

I. Scope The scope of the NEDD lunar sections is described below: Natural environment, as the term is used here, is intended to include all environmental factors, which are independent, i.e., outside the influence, of the Program. Orbital debris and some other man-made environments are included because they are beyond Program control. All induced environments, contamination, and aeroheating, for example, are excluded because they are dependent on system design. Likewise, “environmental impact,” the effects of the Program on the environment, is not within this scope. This document is provided in four main sections, which between them, are intended to include all natural environments needed to support aerospace vehicle design and development activities. The material is divided as follows: a. Terrestrial Environments (Sections 2 through 4) b. Near-Earth Space Environments (Sections 6 through 8) c. Cis-Lunar and Lunar Environments (Sections 10 through 13) d. Mars and Mars Transit Environments (Sections 16 through 21) Cis-Lunar and Lunar Environments focus on the lunar orbital and surface environments. The NEDD is a handbook and source document for the environment models and data needed to support the

Program throughout the development phase. It is not a science text. The intent is to provide a useful tool to the Program and the engineering community. When environment information is needed that has not been provided in the NEDD, the Natural Environments Branch, Marshall Space Flight Center (MSFC), Alabama, should be notified. They will work via approved Program channels to provide the information and update this document as appropriate. Clarification and interpretation of the information contained therein is also the responsibility of the Natural Environments Branch with the concurrence of the Office of the ESMD Chief Engineer. The application of the models and data provided therein, and documentation of the applications, is the responsibility of the user. All Constellation-owned software, including models, simulations, and datasets, use CxP 70065, Constellation Program Computing System Requirements Document, and CxP 70075, Constellation Program Modeling and Simulation Support Plan (SRR Version) for the development, maintenance, and configuration control. Environmental monitoring, forecasting technologies, and models to support the operational phase of the Program must be developed as part of the program architecture. The NEDD document supports the design and development phases only.

II. Table of Contents

In order to describe the types of environments covered in the NEDD, the Table of Contents for the NEDD Lunar Sections follows:

10.0 CIS-LUNAR AND LUNAR ENVIRONMENTS

10.1 INTRODUCTION 10.2 ACRONYMS AND ABBREVIATIONS 10.3 REFERENCES

11.0 CIS-LUNAR SPACE (10 TO 60 Re) 11.1 LUNAR EXOSPHERE (LUNAR ATMOSPHERE) 11.2 THERMAL ENVIRONMENT 11.3 SOLAR WIND (INTERPLANETARY FIELDS) 11.4 PLASMA ENVIRONMENTS

11.4.1 Solar Wind 11.4.2 Magnetosheath and Magnetotail

11.5 IONIZING RADIATION ENVIRONMENT 11.5.1 Solar Particle Events


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11.5.2 Galactic Cosmic Radiation 11.5.3 Total Ionizing Dose 11.5.4 Single Event Effects

11.6 METEOROID ENVIRONMENT 12.0 LUNAR SPACE ENVIRONMENT

12.1 THERMAL ENVIRONMENT 12.1.1 Solar Constant 12.1.2 Lunar Long-Wave Radiance

12.2 PLASMA ENVIRONMENTS 12.2.1 Lunar Plasma (Solar Wind, Magnetosheath, and Magnetotail) Environments 12.2.2 Lunar Wake Plasma 12.2.3 WIND Observations of the Distant Wake 12.2.4 Plasma Interactions and Effects 12.2.5 Plasma Wake Interactions and Spacecraft Effects 12.2.6 Magnetosphere Plasma Interactions and Spacecraft Effects

12.3 IONIZING RADIATION ENVIRONMENT 12.3.1 Solar Particle Events 12.3.2 Galactic Cosmic Radiation 12.3.3 Total Ionizing Dose 12.3.4 Single Event Effects

12.4 METEOROID ENVIRONMENT 12.5 LUNAR GRAVITY

12.5.1 Lunar Gravity Design Model 12.6 LUNAR ECLIPSE

13.0 LUNAR SURFACE ENVIRONMENTS 13.1 PRINCIPAL SURFACE FEATURES; LUNAR HIGHLANDS

13.1.1 Crater Size Distributions 13.1.2 Rock Size Distributions 13.1.3 Slope Distributions

13.2 PRINCIPAL SURFACE FEATURES; MARIA 13.2.1 Crater Size Distributions 13.2.2 Rock Size Distributions 13.2.3 Slope Distributions

13.3 REGOLITH COMPOSITION AND CHARACTERISTICS 13.3.1 Mechanical Properties 13.3.2 Lunar Regolith: Chemical and Magnetic Properties 13.3.3 Lunar Regolith Electrical Properties 13.3.4 Contamination 13.3.5 Lunar Volcanism 13.3.6 The Lunar Interior and Moonquakes

13.4 LUNAR POLES 13.4.1 Solar Illumination Conditions 13.4.2 Volatile Traps

13.5 LUNAR DUST 13.6 THERMAL ENVIRONMENT

13.6.1 Surface Temperature 13.6.2 Subsurface Temperature

13.7 IONIZING RADIATION ENVIRONMENT 13.7.1 Solar Particle Events 13.7.2 Galactic Cosmic Radiation 13.7.3 Lunar Neutron Environment 13.7.4 Total Ionizing Dose 13.7.5 Single Event Effects

13.8 METEOROID ENVIRONMENT 13.8.1 Flux 13.8.2 Lunar Shielding


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13.8.3 Density 13.8.4 Speed 13.8.5 Meteor Showers

13.8.6 Lunar Secondaries

III. Lunar NEDD Editors Writing of the Lunar NEDD Sections was assigned to teams of authors, each team being led by a topical editor.

The editors are listed here:

Overall Lunar NEDD Editor – Dale Ferguson, MSFC

NEDD Book Manager – Leigh Smith, MSFC

Lunar NEDD Writing Team Leads:

Plasma Interactions, Vehicle Charging - Dale Ferguson, MSFC

Radiation Environment, Secondary Radiation - Joe Minow, MSFC

Contamination - Joey Norwood, MSFC

Lunar Regolith Mechanical Properties - Paul Greenberg, GRC

Lunar Regolith Electrical Properties, Dust Charging - Jason Vaughn, MSFC

Lunar Regolith Chemical and Magnetic Properties - Jim Gaier, GRC

Meteoroids - Bill Cooke, MSFC

IV. Examples of Lunar NEDD Sections Below are some Lunar NEDD sections, lifted verbatim from the 09/24/08 version of the NEDD. References are

given in the NEDD reference sections.

Lunar Regolith Electrical Properties

Introduction

Theoretical considerations and observational evidence acquired from Apollo, as well as subsequent lunar missions, indicates that the lunar surface and dust grains are electrostatically charged by the incident solar UV radiation and the solar wind plasma.172,173 On the lunar dayside of the Moon, the dust is believed to be charged positively by photoelectric emissions with the incident solar UV radiation, and predominantly negatively by the incident solar wind electrons on the nightside. There is considerable evidence to indicate that the charged fine lunar dust grains, smaller than a few microns in size, are levitated and transported to high altitudes and transported over long distances across the lunar terminator.174, 175, 176, 177 The lunar dust, with its toxic nature and high adhesive characteristics, constitutes a major source of hazard for humans and the mechanical systems in human and robotic exploration of the Moon.

Although the basic principles and the underlying sources of the observed lunar dust phenomena are recognized, the extent and the details of the lunar dust charging, levitation, and transportation process remain poorly understood. The current theoretical models do not satisfactorily explain the observed lunar dust phenomena. A more definitive


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knowledge of the lunar dust phenomena with acquisition of the basic data is needed for engineering solutions and development of mitigating strategies.

Lunar Dust Charging Processes

The charging of the lunar regolith is a complex process and can be accomplished by many different means. The lunar regolith is typically a non-conductive material suggesting that it can be charged readily by many different means. Electrostatic charging of the lunar regolith and dust can be done by photoelectric emissions produced by UV radiation at wavelengths near 200 nm on the dayside, leading to positively charged grains, with substantial electrostatic charging taking place when the dust is bombarded by soft X-rays with a wavelength <100 nm. Electron or ion collisions on the nightside of the lunar surface produce negatively charged dust grains due to low-energy electrons (<100 eV) impact, and positively charged dust grains due to high-energy electron impact. These different charge states are typically driven by variations in the secondary electron yield of the dust grains.

Triboelectric charging is the other charging process that must be considered. Triboelectric charging of dust grains by contact charging is a process in which electrons are transferred from a solid material with high work function to one with a lower work function, and occurs during landing of a lunar vehicle or movement of an astronaut over the regolith. Triboelectric charging can be exacerbated by trying to remove the dust through brushing, dusting, or blowing. Triboelectric charges can build up rapidly because there is no atmosphere to discharge through, and the regolith is electrically insulating (i.e., there is no common "ground" for electrical equipment). The dust forms unique morphologies, is loosely packed, and is electrically and thermally insulating. The experience of the Apollo astronauts was that the dust is very adherent and abrasive, and hindered the effectiveness of even those very short missions. Mitigation of the effects of charge and dust must be a priority for any mission planned for a long stay on the lunar surface. The source of the problem is twofold: induced charging through triboelectric effects and interactions with naturally occurring background charge.

Effects on Landed Operations: Roving, Power Systems, and Dust

The surface potential and its fluctuations in solar storms can affect landed systems in three ways: roving and charge dissipation, Constellation Program (CxP) Power System, and lunar dust.

a. Roving and charge dissipation: As astronauts rove, they will accumulate triboelectric charge (frictional or contact electricity) with the regolith. In sunlit regions, the photoelectric and ambient plasma currents can dissipate astronaut charge on time scales of < 0.01 seconds. However, in unlit regions where solar wind flow is obstructed (by a large mountain or inside a crater such as Shackleton or Shoemaker), there are little natural environmental currents to remediate any tribocharge build-up. Within the cold craters, the conductivity of the regolith can become as low as 10-14 S/m, rendering them insulators (unable to deliver the needed currents). Recent studies indicate that the dissipation time in unlit craters could be as large as 10-100 seconds. Hence, a rover (continuous charging) or astronaut (charging with each step with a cadence of a second) will charge faster than can be dissipated. As a consequence, roving systems in unlit regions can become Electrostatic Discharge (ESD) hazards.

b. CxP Power System: Any polar base will spend some fraction of time in darkness and away from the photoelectric sheath. As a consequence, the region is susceptible to solar-storm-induced variations in surface potential. Given the poor conductivity of the lunar regolith (making it a poor electrical "ground"), a potential difference can develop between the surface and objects located on the unlit surface during storms. To date, there are no direct measurements of this effect and modeling is just beginning to address this issue. In essence, an object in the unlit region is sitting on an insulator. Consequently, it is recommended that there are clear ground paths for all landed system components to reduce the effect of differential charging, especially during solar storms when the ground and landed components will develop potential differences relative to each other.

Any system venturing into a polar crater should also be aware that the surface in the unlit region is strongly negative relative to any voltage referenced at the crater rim (in daylight). Thus, the use of a tether for power


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will have a ground reference to the sunlit region where the power source is located, but the surface surrounding the exploration system could be many hundreds of volts negative relative to the system ground (referenced to a topside location). Some consideration should be given to mitigating this ESD risk.

c. Lunar dust: At terminator/polar regions, where electric fields are expected to be large (see Figure 13.3.3.4.1-2), the dust environment becomes active. The Lunar Ejecta and Meteorite (LEAM) experiment, an Apollo 17 ALSEP package, detected incidence of highly energetic lifted dust grains with speeds >100 m/s at both terminator crossings Berg et al.145 The dust was detected in all directions but was primarily moving in nightside directions. The activity peaked at the terminators but extended well into the nightside. Figure 13.3.3.4.4-1 shows the incidence of naturally-lifted grains as detected by LEAM with detection of these energized grains at one every couple of minutes. Since LEAM was relativity insensitive to low-energy dust, it is anticipated that there is a progressively larger flux of natural dust at progressively lower speeds (a distribution of dust that increases with density at decreasing velocities) and that LEAM is detecting only the most energetic lofted grains at the "tail" of the distribution. However, landed instrumentation is required to confirm this possibility. The naturally-lifted lunar dust is an indicator of locations where near-surface electric fields may become large.

V. Conclusions The Constellation Program Natural Environments Definition for Design has been supplemented with Sections on

Lunar Environments. These sections of this document will serve as the basis for writing the lunar sections of the Design Specification for Natural Environments (DSNE), an official specification document for the Constellation Program. Along with the DSNE, the NEDD will allow confident and reliable design of Constellation Program missions to the moon.

VII. Acknowledgments This paper could not have been written without the contributions to the NEDD of all the lunar writers, including

Kai Hwang, Bill Farrell, Linda Parker, Joe Minow, Albert Whittlesey, Jim Howard, Marge Bruce, Joey Norwood, Jonathan Campbell, Keith Albyn, Paul Greenberg, Ram Ramachandran, Barbara Cohen, Doug Rickman, Jeff Plescia, Jason Vaughn, Todd Schneider, Mian Abbas, Carlos Calle, Barry Hillard, Jim Gaier, Bob Richmond, John Lindsey, Steve Wilson, Sara Majetic, Bill Cooke, and Ron Suggs. Our very special thanks to the Constellation Program Chief Lunar Scientist, Wendell Mendell.

Lunar Natural Environment for Lunar Natural Environment for Use by the ConstellationUse by the Constellation

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What is the purpose of the NEDD?

♦♦The Natural Environments Definition for Design:The Natural Environments Definition for Design:The purpose of this document is to provide a uniform description ofThe purpose of this document is to provide a uniform description ofThe purpose of this document is to provide a uniform description of The purpose of this document is to provide a uniform description of

the natural environment to serve as a basic framework for both the the natural environment to serve as a basic framework for both the crewed and robotic missions of the Exploration Systems Mission crewed and robotic missions of the Exploration Systems Mission Directorate (ESMD)Directorate (ESMD) It is intended to support engineering andIt is intended to support engineering andDirectorate (ESMD).Directorate (ESMD). It is intended to support engineering and It is intended to support engineering and analysis, requirements development, and verification involved in the analysis, requirements development, and verification involved in the development of exploration concepts and architectures, flight development of exploration concepts and architectures, flight hardware and new technologies (It does not support the operationalhardware and new technologies (It does not support the operationalhardware, and new technologies. (It does not support the operational hardware, and new technologies. (It does not support the operational phases of the Program since models and data with different phases of the Program since models and data with different properties are needed for those applications.) By presenting a single properties are needed for those applications.) By presenting a single benchmark definition of natural environment parameters it providesbenchmark definition of natural environment parameters it providesbenchmark definition of natural environment parameters it provides benchmark definition of natural environment parameters it provides an easily accessible and uniform baseline for competitive studies, an easily accessible and uniform baseline for competitive studies, independent analyses, and concept studies. independent analyses, and concept studies.

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What is the purpose of the NEDD?

Th N l E i D fi i i f D iTh N l E i D fi i i f D i♦♦The Natural Environments Definition for Design:The Natural Environments Definition for Design:This document is a requirement in the sense that its use is directed by This document is a requirement in the sense that its use is directed by

the Program, but the Program, but it does not containit does not contain any requirement “any requirement “shallshall” ” gg y qy qlanguage. It provides a single description of each environment that language. It provides a single description of each environment that requirements may be written against, thereby enabling clear requirements may be written against, thereby enabling clear definition of contract scope and control. By providing a complete and definition of contract scope and control. By providing a complete and single source for environment data, the document also reduces single source for environment data, the document also reduces system development cost by providing a ready source of required system development cost by providing a ready source of required technical data and minimizing the environment related efforts technical data and minimizing the environment related efforts required of the contractor community. Since the definitions specified required of the contractor community. Since the definitions specified herein are, for the most part, definitions developed and used on prior herein are, for the most part, definitions developed and used on prior programs, they are well understood by NASA and significant portions programs, they are well understood by NASA and significant portions of the contractor community. Thus, use of this book enables a better of the contractor community. Thus, use of this book enables a better understanding of Program technical risk than would be possible understanding of Program technical risk than would be possible without a baselined definition document.without a baselined definition document.

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What is the scope of the NEDD Lunar Sections?

♦♦Scope of the Natural Environments Definition for Scope of the Natural Environments Definition for Design:Design:

Natural environment, as the term is used here, is intended to include all Natural environment, as the term is used here, is intended to include all environmental factors, which are independent, i.e., outside the environmental factors, which are independent, i.e., outside the influence, of the Program. Orbital debris and some other maninfluence, of the Program. Orbital debris and some other man--made made environments are included because they are beyond Program control. environments are included because they are beyond Program control. All All induced environmentsinduced environments, contamination, and aeroheating, for , contamination, and aeroheating, for

ll l d dl d d b th d d t t d ib th d d t t d iexample, example, are excludedare excluded because they are dependent on system design. because they are dependent on system design. Likewise, “environmental impact,” the effects of the Program on the Likewise, “environmental impact,” the effects of the Program on the environment, is not within this scope. This document is provided in environment, is not within this scope. This document is provided in four main sections, which between them, are intended to include all four main sections, which between them, are intended to include all natural environments needed to support aerospace vehicle designnatural environments needed to support aerospace vehicle designnatural environments needed to support aerospace vehicle design natural environments needed to support aerospace vehicle design and development activities. The material is divided as follows:and development activities. The material is divided as follows:

a. Terrestrial Environments (Sections 2 through 4)a. Terrestrial Environments (Sections 2 through 4)b. Nearb. Near--Earth Space Environments (Sections 6 through 8)Earth Space Environments (Sections 6 through 8)c. Cisc. Cis--Lunar and Lunar Environments (Sections 10 through 13)Lunar and Lunar Environments (Sections 10 through 13)d. Mars and Mars Transit Environments (Sections 16 through 21)d. Mars and Mars Transit Environments (Sections 16 through 21)

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CisCis--Lunar and Lunar Environments focus on the lunar orbital and Lunar and Lunar Environments focus on the lunar orbital and surface environments.surface environments.

What is the scope of the NEDD Lunar Sections? (cont.)

This document is a handbook and source document for the This document is a handbook and source document for the environment models and data needed to support the Program environment models and data needed to support the Program pp gpp gthroughout the throughout the development development phase. It is not a science text. The phase. It is not a science text. The intent is to provide a useful tool to the Program and the engineering intent is to provide a useful tool to the Program and the engineering community. community. When environment information is needed that has not When environment information is needed that has not been provided in this document the Natural Environments Branch, been provided in this document the Natural Environments Branch, Marshall Space Flight Center (MSFC), Alabama, should be notified.Marshall Space Flight Center (MSFC), Alabama, should be notified.They will work via approved Program channels to provide the They will work via approved Program channels to provide the i f ti d d t thi d t i t Cl ifi tii f ti d d t thi d t i t Cl ifi tiinformation and update this document as appropriate. Clarification information and update this document as appropriate. Clarification and interpretation of the information contained herein is also the and interpretation of the information contained herein is also the responsibility of the Natural Environments Branch with the responsibility of the Natural Environments Branch with the concurrence of the Office of the ESMD Chief Engineerconcurrence of the Office of the ESMD Chief Engineerconcurrence of the Office of the ESMD Chief Engineer. concurrence of the Office of the ESMD Chief Engineer.

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Table of Contents for NEDD Lunar Sections

♦♦10.010.0 CISCIS--LUNAR AND LUNAR ENVIRONMENTSLUNAR AND LUNAR ENVIRONMENTS•• 10.1 INTRODUCTION10.1 INTRODUCTION•• 10.210.2 ACRONYMS AND ABBREVIATIONSACRONYMS AND ABBREVIATIONS•• 10.310.3 REFERENCESREFERENCES

♦♦11.011.0 CISCIS--LUNAR SPACE (10 TO 60 Re)LUNAR SPACE (10 TO 60 Re)11 111 1 LUNAR EXOSPHERE (LUNAR ATMOSPHERE)LUNAR EXOSPHERE (LUNAR ATMOSPHERE)•• 11.111.1 LUNAR EXOSPHERE (LUNAR ATMOSPHERE)LUNAR EXOSPHERE (LUNAR ATMOSPHERE)

•• 11.211.2 THERMAL ENVIRONMENTTHERMAL ENVIRONMENT•• 11.311.3 SOLAR WIND (INTERPLANETARY FIELDS)SOLAR WIND (INTERPLANETARY FIELDS)•• 11.411.4 PLASMA ENVIRONMENTSPLASMA ENVIRONMENTS

−− 11.4.111.4.1 Solar WindSolar Wind−− 11.4.211.4.2 Magnetosheath and MagnetotailMagnetosheath and Magnetotail

•• 11.511.5 IONIZING RADIATION ENVIRONMENTIONIZING RADIATION ENVIRONMENT−− 11.5.111.5.1 Solar Particle EventsSolar Particle Events11.5.111.5.1 Solar Particle EventsSolar Particle Events−− 11.5.211.5.2 Galactic Cosmic RadiationGalactic Cosmic Radiation−− 11.5.311.5.3 Total Ionizing DoseTotal Ionizing Dose−− 11.5.411.5.4 Single Event EffectsSingle Event Effects

•• 11.611.6 METEOROID ENVIRONMENTMETEOROID ENVIRONMENT

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11.611.6 METEOROID ENVIRONMENTMETEOROID ENVIRONMENT

Table of Contents for NEDD Lunar Sections (cont.)

♦♦12.012.0 LUNAR SPACE ENVIRONMENTLUNAR SPACE ENVIRONMENT•• 12.1 THERMAL ENVIRONMENT12.1 THERMAL ENVIRONMENT

−− 12.1.112.1.1 Solar ConstantSolar Constant−− 12.1.212.1.2 Lunar LongLunar Long--Wave RadianceWave Radiance

•• 12.212.2 PLASMA ENVIRONMENTSPLASMA ENVIRONMENTS−− 12.2.112.2.1 Lunar Plasma (Solar Wind, Magnetosheath, and Lunar Plasma (Solar Wind, Magnetosheath, and ( , g ,( , g ,

Magnetotail) EnvironmentsMagnetotail) Environments−− 12.2.212.2.2 Lunar Wake PlasmaLunar Wake Plasma−− 12.2.312.2.3 WIND Observations of the Distant WakeWIND Observations of the Distant Wake−− 12.2.412.2.4 Plasma Interactions and EffectsPlasma Interactions and Effects−− 12.2.512.2.5 Plasma Wake Interactions and Spacecraft EffectsPlasma Wake Interactions and Spacecraft Effects−− 12.2.612.2.6 Magnetosphere Plasma Interactions and Spacecraft Magnetosphere Plasma Interactions and Spacecraft

EffectsEffects•• 12.3 IONIZING RADIATION ENVIRONMENT12.3 IONIZING RADIATION ENVIRONMENT

−− 12.3.112.3.1 Solar Particle EventsSolar Particle Events−− 12.3.212.3.2 Galactic Cosmic RadiationGalactic Cosmic Radiation−− 12.3.312.3.3 Total Ionizing DoseTotal Ionizing Dose−− 12.3.412.3.4 Single Event EffectsSingle Event Effects

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•• 12.412.4 METEOROID ENVIRONMENTMETEOROID ENVIRONMENT

Table of Contents for NEDD Lunar Sections (cont.) •• 12 5 LUNAR GRAVITY12 5 LUNAR GRAVITY•• 12.5 LUNAR GRAVITY12.5 LUNAR GRAVITY

−− 12.5.112.5.1 Lunar Gravity Design ModelLunar Gravity Design Model•• 12.6 LUNAR ECLIPSE12.6 LUNAR ECLIPSE

♦♦13 0 LUNAR SURFACE ENVIRONMENTS13 0 LUNAR SURFACE ENVIRONMENTS♦♦13.0 LUNAR SURFACE ENVIRONMENTS13.0 LUNAR SURFACE ENVIRONMENTS•• 13.1 PRINCIPAL SURFACE FEATURES; LUNAR HIGHLANDS13.1 PRINCIPAL SURFACE FEATURES; LUNAR HIGHLANDS

−− 13.1.113.1.1 Crater Size DistributionsCrater Size Distributions−− 13.1.213.1.2 Rock Size DistributionsRock Size Distributions33 oc S e s bu o soc S e s bu o s−− 13.1.313.1.3 Slope DistributionsSlope Distributions

•• 13.2 PRINCIPAL SURFACE FEATURES; MARIA13.2 PRINCIPAL SURFACE FEATURES; MARIA−− 13.2.113.2.1 Crater Size DistributionsCrater Size Distributions−− 13.2.213.2.2 Rock Size DistributionsRock Size Distributions−− 13.2.313.2.3 Slope DistributionsSlope Distributions

•• 13.3 REGOLITH COMPOSITION AND CHARACTERISTICS13.3 REGOLITH COMPOSITION AND CHARACTERISTICS−− 13.3.113.3.1 Mechanical PropertiesMechanical Properties−− 13.3.213.3.2 Lunar Regolith: Chemical and Magnetic PropertiesLunar Regolith: Chemical and Magnetic Properties−− 13.3.313.3.3 Lunar Regolith Electrical PropertiesLunar Regolith Electrical Properties13 3 413 3 4 ContaminationContamination

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−− 13.3.413.3.4 ContaminationContamination−− 13.3.513.3.5 Lunar VolcanismLunar Volcanism−− 13.3.613.3.6 The Lunar Interior and MoonquakesThe Lunar Interior and Moonquakes

Table of Contents for NEDD Lunar Sections (cont.)

•• 13 4 LUNAR POLES13 4 LUNAR POLES13.4 LUNAR POLES13.4 LUNAR POLES−− 13.4.113.4.1 Solar Illumination ConditionsSolar Illumination Conditions−− 13.4.213.4.2 Volatile TrapsVolatile Traps

•• 13.5 LUNAR DUST13.5 LUNAR DUST•• 13.6 THERMAL ENVIRONMENT13.6 THERMAL ENVIRONMENT

−− 13.6.113.6.1 Surface TemperatureSurface Temperature−− 13.6.213.6.2 Subsurface TemperatureSubsurface Temperature

•• 13 713 7 IONIZING RADIATION ENVIRONMENTIONIZING RADIATION ENVIRONMENT•• 13.713.7 IONIZING RADIATION ENVIRONMENTIONIZING RADIATION ENVIRONMENT−− 13.7.113.7.1 Solar Particle EventsSolar Particle Events−− 13.7.213.7.2 Galactic Cosmic RadiationGalactic Cosmic Radiation−− 13.7.313.7.3 Lunar Neutron EnvironmentLunar Neutron Environment−− 13.7.413.7.4 Total Ionizing DoseTotal Ionizing Dose−− 13.7.513.7.5 Single Event EffectsSingle Event Effects

•• 13.8 METEOROID ENVIRONMENT13.8 METEOROID ENVIRONMENT−− 13.8.113.8.1 FluxFlux13.8.113.8.1 FluxFlux−− 13.8.213.8.2 Lunar ShieldingLunar Shielding−− 13.8.313.8.3 DensityDensity−− 13.8.413.8.4 SpeedSpeed13 8 513 8 5 Meteor Sho ersMeteor Sho ers

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−− 13.8.513.8.5 Meteor ShowersMeteor Showers−− 13.8.613.8.6 Lunar SecondariesLunar Secondaries

Examples of NEDD Lunar Sections

♦♦13.3.3.2 Lunar Dust Charging Processes13.3.3.2 Lunar Dust Charging Processes♦♦The charging of the lunar regolith is a complex process and can beThe charging of the lunar regolith is a complex process and can be♦♦The charging of the lunar regolith is a complex process and can be The charging of the lunar regolith is a complex process and can be

accomplished by many different means. The lunar regolith is a accomplished by many different means. The lunar regolith is a typically a nontypically a non--conductive material suggesting that it can be charged conductive material suggesting that it can be charged readily by many different means. readily by many different means.

♦♦Electrostatic charging of the lunar regolith and dust can be done by Electrostatic charging of the lunar regolith and dust can be done by photoelectric emissions produced by UV radiation at wavelengths photoelectric emissions produced by UV radiation at wavelengths near 200 nm on the day side, leading to positively charged grains. near 200 nm on the day side, leading to positively charged grains. With substantial electrostatic changing taking place when the dust isWith substantial electrostatic changing taking place when the dust isWith substantial electrostatic changing taking place when the dust is With substantial electrostatic changing taking place when the dust is bombarded by soft xbombarded by soft x--rays with a wavelength < 100 nm. Electron or ion rays with a wavelength < 100 nm. Electron or ion collisions on the night side of the lunar surface produce negatively collisions on the night side of the lunar surface produce negatively charged dust grains due to low energy electrons (< 100 eV) impact, charged dust grains due to low energy electrons (< 100 eV) impact, and positively charged dust grains due to high energy electron and positively charged dust grains due to high energy electron impact. impact. These different charge states are typically driven by variations These different charge states are typically driven by variations in the secondary electron yield of the dust grains.in the secondary electron yield of the dust grains.

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♦♦The other charging process that must be considered is that of The other charging process that must be considered is that of triboelectric chargingtriboelectric charging. Triboelectric charging of dust grains by contact . Triboelectric charging of dust grains by contact charging process in which electrons are transferred from a solid charging process in which electrons are transferred from a solid material with high work function to one with a lower work function will material with high work function to one with a lower work function will occur during landing of a lunar vehicle or movement of an astronaut occur during landing of a lunar vehicle or movement of an astronaut over the regolith. Triboelectric charging can be exacerbated by trying over the regolith. Triboelectric charging can be exacerbated by trying to remove the dust through brushing dusting or blowing Triboelectricto remove the dust through brushing dusting or blowing Triboelectricto remove the dust through brushing, dusting or blowing. Triboelectric to remove the dust through brushing, dusting or blowing. Triboelectric charges can build up rapidly because there is no atmosphere to charges can build up rapidly because there is no atmosphere to discharge through, and the regolith is electrically insulating (i.e., there discharge through, and the regolith is electrically insulating (i.e., there is no common “ground” for electrical equipment). The dust forms is no common “ground” for electrical equipment). The dust forms

i h l i i l l k d d i l t i ll di h l i i l l k d d i l t i ll dunique morphologies, is loosely packed, and is electrically and unique morphologies, is loosely packed, and is electrically and thermally insulating. The experience of the Apollo astronauts was that thermally insulating. The experience of the Apollo astronauts was that the dust is very adherent and abrasive, and hindered the effectiveness the dust is very adherent and abrasive, and hindered the effectiveness of even those very short missions. of even those very short missions. Mitigation of the effects of charge Mitigation of the effects of charge yy g gg gand dust must be a priority for any mission planned for a long stay on and dust must be a priority for any mission planned for a long stay on the lunar surfacethe lunar surface. The source of the problem is twofold: induced . The source of the problem is twofold: induced charging through triboelectric effects and interactions with naturallycharging through triboelectric effects and interactions with naturally--occurring background chargeoccurring background charge

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occurring background charge.occurring background charge.


♦♦13.3.3.4.1 A description of the surface and near surface 13.3.3.4.1 A description of the surface and near surface electrical environmentelectrical environment

Figure 13 3 3 4 1Figure 13 3 3 4 1--1 shows the near1 shows the near--surface electrical environmentsurface electrical environmentFigure 13.3.3.4.1Figure 13.3.3.4.1 1 shows the near1 shows the near surface electrical environment, surface electrical environment, characterized by three major regions: a) Dayside region … b) Nightside characterized by three major regions: a) Dayside region … b) Nightside region...c) Terminator/polar region.region...c) Terminator/polar region.

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♦♦13.3.3.4.4 Effects on Landed Operations: Roving, Power 13.3.3.4.4 Effects on Landed Operations: Roving, Power Systems, and DustSystems, and Dust

♦♦The surface potential and its fluctuations in solar storms can The surface potential and its fluctuations in solar storms can ff t l d d t i thff t l d d t i thaffect landed systems in three ways:affect landed systems in three ways:

1) Roving and charge dissipation 1) Roving and charge dissipation –– As astronauts rove, they will As astronauts rove, they will accumulate triboelectric charge (frictional or contact electricity) accumulate triboelectric charge (frictional or contact electricity) with the regolith. In sunlit regions, the photoelectric and with the regolith. In sunlit regions, the photoelectric and g g , pg g , pambient plasma currents can dissipate astronaut charge on time ambient plasma currents can dissipate astronaut charge on time scales of < 0.01 seconds. However, in unlit regions where solar scales of < 0.01 seconds. However, in unlit regions where solar wind flow is obstructed (by a large mountain or inside a crater wind flow is obstructed (by a large mountain or inside a crater like Shackleton or Shoemaker), there are little natural like Shackleton or Shoemaker), there are little natural ),),environmental currents to remediate any tribocharge buildenvironmental currents to remediate any tribocharge build--up. up. Within the cold craters, the conductivity of the regolith can Within the cold craters, the conductivity of the regolith can become as low as 10become as low as 10--1414 S/m, rendering them insulators (unable S/m, rendering them insulators (unable to deliver the needed currents). Recent studies indicate that the to deliver the needed currents). Recent studies indicate that the ))dissipation time in unlit craters could be as large as 10dissipation time in unlit craters could be as large as 10--100 100 secondsseconds. Hence, a rover (continuous charging) or astronaut . Hence, a rover (continuous charging) or astronaut (charging with each step with a cadence of a second) will charge (charging with each step with a cadence of a second) will charge faster than can be dissipated. As a consequence, roving faster than can be dissipated. As a consequence, roving

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p q , gp q , gsystems in unlit regions can become ESD hazards.systems in unlit regions can become ESD hazards.


2) CxP Power System 2) CxP Power System –– Any polar base will spend some fraction Any polar base will spend some fraction f ff f

♦♦13.3.3.4.4 Effects on Landed Operations: Roving, Power Systems, 13.3.3.4.4 Effects on Landed Operations: Roving, Power Systems, and Dust (cont.)and Dust (cont.)

of time in darkness and away from the photoelectric sheath. As of time in darkness and away from the photoelectric sheath. As a consequence, the region is susceptible to a consequence, the region is susceptible to solarsolar--stormstorm--induced induced variations in surface potentialvariations in surface potential. Given the poor conductivity of . Given the poor conductivity of the lunar regolith (making it a poor electrical “ground”), a the lunar regolith (making it a poor electrical “ground”), a

i l diff d l b h f di l diff d l b h f dpotential difference can develop between the surface and potential difference can develop between the surface and objects located on the unlit surface during storms. To date, objects located on the unlit surface during storms. To date, there are not direct measurements of this effect and modeling is there are not direct measurements of this effect and modeling is just beginning to address this issue. In essence, an object in the just beginning to address this issue. In essence, an object in the

lit i i itti i l tlit i i itti i l tunlit region is sitting on an insulator.unlit region is sitting on an insulator.Consequently, it is recommended that there are clear ground Consequently, it is recommended that there are clear ground

paths for all landed system components to reduce the effect of paths for all landed system components to reduce the effect of differential charging, especially during solar storms when the differential charging, especially during solar storms when the g g, p y gg g, p y gground and landed components will develop potential ground and landed components will develop potential differences relative to each otherdifferences relative to each other..

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♦♦13.3.3.4.4 Effects on Landed Operations: Roving, Power Systems, 13.3.3.4.4 Effects on Landed Operations: Roving, Power Systems, and Dust (cont.)and Dust (cont.)

Any system venturing into a polar crater should also be aware that Any system venturing into a polar crater should also be aware that the surface in the the surface in the unlit region is strongly negativeunlit region is strongly negative relative to any relative to any voltage referenced at the crater rim (in daylight). Thus, the use of a voltage referenced at the crater rim (in daylight). Thus, the use of a tether for power will have a ground references to the sunlit region tether for power will have a ground references to the sunlit region p g gp g gwhere the power source is located, but the surface surrounding the where the power source is located, but the surface surrounding the exploration system could be many exploration system could be many hundreds of volts negativehundreds of volts negativerelative to the system ground (referenced to a topside location). relative to the system ground (referenced to a topside location). Some consideration should be given to mitigating this Some consideration should be given to mitigating this ESD riskESD risk..g g gg g g

3) Lunar dust 3) Lunar dust –– At terminator/polar regions where electric fields are At terminator/polar regions where electric fields are expected to be large (see Figure 13.3.3.4.1expected to be large (see Figure 13.3.3.4.1--2), the dust environment 2), the dust environment becomes active. The Lunar Ejecta and Meteorite (LEAM) becomes active. The Lunar Ejecta and Meteorite (LEAM) experiment an Apollo 17 ALSEP package detected incidence ofexperiment an Apollo 17 ALSEP package detected incidence ofexperiment, an Apollo 17 ALSEP package, detected incidence of experiment, an Apollo 17 ALSEP package, detected incidence of highly energetic lifted dust grains with speeds > 100 m/s at both highly energetic lifted dust grains with speeds > 100 m/s at both terminator crossings [Berg et al., 1973]. The dust was detected in terminator crossings [Berg et al., 1973]. The dust was detected in all directions but primarily moving in nightside directions. The all directions but primarily moving in nightside directions. The activity peaked at the terminators, but extended well into theactivity peaked at the terminators, but extended well into the

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activity peaked at the terminators, but extended well into the activity peaked at the terminators, but extended well into the nightside. nightside.


♦♦13.3.3.4.4 Effects on Landed Operations: Roving, Power 13.3.3.4.4 Effects on Landed Operations: Roving, Power Systems, and Dust (cont.)Systems, and Dust (cont.)

Figure 13 3 3 4 4Figure 13 3 3 4 4 2 shows the incidence of naturally2 shows the incidence of naturally liftedliftedFigure 13.3.3.4.4Figure 13.3.3.4.4--2 shows the incidence of naturally2 shows the incidence of naturally--lifted lifted grains as detected by LEAM with detection of these energized grains as detected by LEAM with detection of these energized grains at one aver couple minutes. Since LEAM was relativity grains at one aver couple minutes. Since LEAM was relativity insensitive to low energy dust, it is anticipated that there is a insensitive to low energy dust, it is anticipated that there is a progressively larger flux of natural dust at progressivelyprogressively larger flux of natural dust at progressivelyprogressively larger flux of natural dust at progressively progressively larger flux of natural dust at progressively lower speeds (a distribution of dust that increases with lower speeds (a distribution of dust that increases with density at decreasing velocities) and that density at decreasing velocities) and that LEAM is detecting LEAM is detecting only the most energetic lofted grains at the “tail” of the only the most energetic lofted grains at the “tail” of the distributiondistribution However landed instrumentation is required toHowever landed instrumentation is required todistributiondistribution. However, landed instrumentation is required to . However, landed instrumentation is required to confirm this possibility. The naturallyconfirm this possibility. The naturally--lifted lunar dust is an lifted lunar dust is an indicator of locations where near surface electric fields may indicator of locations where near surface electric fields may become large. Figure 13.3.3.4.1become large. Figure 13.3.3.4.1--2 indicates that driving E 2 indicates that driving E fields may indeed peak where LEAM dust is most active atfields may indeed peak where LEAM dust is most active atfields may indeed peak where LEAM dust is most active at fields may indeed peak where LEAM dust is most active at the terminator. Such an electrical environment would also the terminator. Such an electrical environment would also have an impact on any anthropogenicallyhave an impact on any anthropogenically--lofted dust since lofted dust since there is an there is an induced potentialinduced potential on both the roving astronaut on both the roving astronaut and the dust that may furtherand the dust that may further increase their electrostaticincrease their electrostatic

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and the dust that may further and the dust that may further increase their electrostatic increase their electrostatic attractionattraction..


FIGURE 13.3.3.4.4-2: ACCELERATED DUST IMPACTS DETECTED BY APOLLO 17 LEAM SURFACE

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PACKAGE

Conclusions

The Constellation Program Natural Environments DefinitionThe Constellation Program Natural Environments Definition for Design has been supplemented with Sections on Lunar Environments. These sections of this document will serve

th b i f iti th l ti f th D ias the basis for writing the lunar sections of the Design Specification for Natural Environments (DSNE), an official specification document for the Constellation Program. Along with the DSNE, the NEDD will allow confident and reliable design of Constellation Program missions to the moon.

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Acknowledgments

This paper could not have been written without the contributions to the NEDD of all the lunar writers, including Kai Hwang, Bill Farrell, Linda Parker, Joe Minow, Albert Whittlesey, Jim Howard, Marge Bruce, Joey Norwood, Jonathan Campbell, Keith Albyn, Paul G b R R h d B b C h DGreenberg, Ram Ramachandran, Barbara Cohen, Doug Rickman, Jeff Plescia, Jason Vaughn, Todd Schneider, Mian Abbas, Carlos Calle, Barry Hillard, Jim Gaier, Bob Richmond John Lindsey Steve Wilson Sara Majetic BillRichmond, John Lindsey, Steve Wilson, Sara Majetic, Bill Cooke, and Ron Suggs. Our very special thanks to the Constellation Program Chief Lunar Scientist, Wendell Mendell.

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Mendell.

Documents

11.5.1 SOLAR PARTICLE EVENTS - NASA · By presenting a single benchmark definition of natural environment ... Branch with the concurrence of the Office of the ESMD Chief Engineer