NASAA Special Publication 6107

Human Exploration of Mars:

The Reference Mission of the NASA Mars Exploration Study Team

Stephen J. Hoffman, Editor David I. Kaplan, Editor

Lyndon B. Johnson Space Center Houston, Texas

July 1997

Foreword

Mars has long beckoned to humankind interest in this fellow traveler of the solar from its travels high in the night sky. The system, adding impetus for exploration. ancients assumed this rust-red wanderer was Over the past several years studies the god of war and christened it with the have been conducted on various approaches name we still use today. to exploring Earth’s sister planet Mars. Much Early explorers armed with newly has been learned, and each study brings us invented telescopes discovered that this closer to realizing the goal of sending humans planet exhibited seasonal changes in color, to conduct science on the Red Planet and was subjected to dust storms that encircled explore its mysteries. The approach described the globe, and may have even had channels in this publication represents a culmination of that crisscrossed its surface. these efforts but should not be considered the final solution. It is our intent that this Recent explorers, using robotic document serve as a reference from which we surrogates to extend their reach, have can continuously compare and contrast other discovered that Mars is even more complex new innovative approaches to achieve our and fascinating—a planet peppered with long-term goal. A key element of future craters, cut by canyons deep enough to improvements to this document will be the swallow the Earth’s Grand Canyon, and incorporation of an integrated robotic/human shouldering the largest known volcano in the exploration strategy currently under solar system. They found intriguing evidence development. that water played an important role on Mars with channels that bear a striking We will continue to develop alternative resemblance to stream beds and clouds of approaches, technologies, precursor missions, crystalline ice that still traverse its red sky. and flight demonstrations that collectively But they also found that Mars was cold and move us forward. Inputs have been, and will dry, and believed to be devoid of life. always be, encouraged from all sources— NASA centers, industry, research Now present day explorers have organizations, entrepreneurs, government announced that pieces of Mars have arrived agencies, international partners, and the on Earth as meteorites, and that these bits of public at large—which will improve our the red planet contain evidence pointing to understanding and current planning. We the possible existence of life early in Mars plan to use the results of these assessments to history. This has resulted in renewed public shape our investments in technology, and to

III look for high leverage, innovative, break- must search for alternatives to substantially through approaches to the most cost effective reduce the cost of exploration, while exploration. These data will also help us increasing the inherent value to humankind. understand the required infrastructure, as This Reference Mission provides a viable well as provide important insights into how starting point for NASA’s continuing efforts we can use the International Space Station to to develop the technologies and systems, as validate key assumptions and technologies. well as the international partnerships, needed for the grand adventure of sending humans to To achieve our goal, we must explore another planet in our solar system— fundamentally change the way in which we one that may have once, and may yet again, explore with both humans and robots. We harbor life.

IV Acknowledgments

Sending people to Mars has been a will be added to and improved upon by long-held dream of humankind, and many others in the future. This report has benefited have approached the task of turning the from the contributions and advice of many dream into reality. This document is another individuals from the government and private chapter in the ongoing process of melding sectors. The individuals listed on the new and existing technologies, practical following page assisted in preparing the operations, fiscal reality, and common sense concepts described in this report and in into a feasible and viable human mission to compiling the words, images, and data used Mars. However, this is not the last chapter in for that description. the process, but marks a snapshot in time that

Stephen J. Hoffman

David I. Kaplan

V Contributing Authors Los Alamos National Laboratory: Dr. Paul Keaton Ames Research Center: Roger Arno Marshall Space Flight Center: Dr. Geoff Briggs William Huber Dr. Yvonne Clearwater General Contributors Dr. Marc Cohen Andy Gonzales Ames Research Center: Betsy Dunsky Johnson Space Center: Paul Espinosa Dr. Michael Duke Vladimir Garin David Kaplan Lynn Harper Catherine Larson Butler Hine David Weaver Larry Lemke Laurie Weaver Doug O’Handley Lewis Research Center: Nelson Schlater Robert Cataldo Michael Sims Dr. Stanley Borowski Boeing: SAIC: Brent Sherwood Dr. Stephen Hoffman Lewis Research Center: Paul Phillips Dr. Stanley Borowski Study Team Members Rockwell International: Ames Research Center: Robert Raasch Dr. Geoff Briggs (co-lead) Lisa Rockoff Johnson Space Center: Reviewers and Commenters Jeri Brown Johnson Space Center: Nancy Ann Budden Nancy Ann Budden Beth Caplan John Connolly John Connolly Dr. Michael Duke (co-lead) Other Support and Contributions Dallas Evans Dr. Steve Hawley Ames Research Center: Kent Joosten Dr. Chris McKay David Kaplan Jeff Moore Darrell Kendrick Dr. Carol Stoker Barbara Pearson Anthony Gross Barney Roberts Editorial and Graphics Support Ed Svrcek David Weaver J. Frassanito and Associates: J. Frassanito Lewis Research Center: Dr. Stanley Borowski SAIC: Robert Cataldo R. Patrick Rawlings

VI There is a set of supplemental technical reports which provide greater depth into many of the design features of the Mars Reference Mission than is given in section 3 of this document. Had those papers been included as appendices, the size of this document would have greatly expanded. Consequently, we decided to make those supplemental materials available through the world wide web. We intend to post new materials as to the web as they are produced and hope to maintain a site with the latest information which describes key technologies and design features of a human mission to Mars.

The site for the Mars Reference Mission is

http://www_sn.jsc.nasa.gov/marsref/contents.html

VII VIII Contents

Section Page

Acronyms ...... xv

1. OVERVIEW AND EXECUTIVE SUMMARY ...... 1-1 1.1 INTRODUCTION ...... 1-3 1.2 BACKGROUND...... 1-5 1.3 REFERENCE MISSION EXECUTIVE SUMMARY ...... 1-6 1.3.1 Objectives ...... 1-6 1.3.2 Groundrules and Assumptions ...... 1-7 1.3.3 Mission and Systems ...... 1-8 1.3.3.1 Mission Design ...... 1-8 1.3.3.2 In Situ Resource Production ...... 1-16 1.3.3.3 Flight Crew ...... 1-16 1.3.3.4 Robotic Precursors ...... 1-17 1.3.3.5 Launch Systems ...... 1-18 1.3.3.6 Interplanetary Transportation Systems ...... 1-18 1.3.3.7 Surface Systems ...... 1-22 1.3.3.8 Operations ...... 1-24 1.3.3.9 Mission and Systems Summary ...... 1-27 1.4 TESTING PRINCIPAL ASSUMPTIONS AND CHOICES ...... 1-28 1.4.1 Robust Surface Infrastructure ...... 1-28 1.4.2 Split Mission Strategy ...... 1-28 1.4.3 Nuclear Thermal Propulsion ...... 1-30 1.4.4 In Situ Resource Utilization ...... 1-30 1.4.5 Common Habitat Design ...... 1-31 1.4.6 Nuclear Surface Power ...... 1-31 1.4.7 Abort to the Surface ...... 1-32 1.4.8 Design for the Most Difficult Opportunity ...... 1-33 1.5 CONCLUSIONS AND RECOMMENDATIONS ...... 1-33 1.5.1 Mission and Systems ...... 1-33 1.5.2 Technology Development ...... 1-34 1.5.3 Environmental Protection ...... 1-37 1.5.4 Program Cost ...... 1-38 1.5.5 International Participation ...... 1-39 1.5.6 Program Management and Organization...... 1-41 1.6 REFERENCES ...... 1-44

IX Section Page 2. SCIENCE AND EXPLORATION RATIONALE ...... 2-1 2.1 INTRODUCTION ...... 2-3 2.2 THE “WHY MARS” WORKSHOP ...... 2-3 2.3 SCIENCE RATIONALE ...... 2-6 2.4 EXPLORATION RATIONALE...... 2-13 2.4.1 Inhabiting Another Planet...... 2-13 2.4.2 International Cooperation ...... 2-15 2.4.3 Technological Advancement...... 2-16 2.4.4 Inspiration ...... 2-18 2.4.5 Investment ...... 2-19 2.5 WHY NOT MARS? ...... 2-19 2.5.1 Human Performance...... 2-19 2.5.2 System Reliability and Lifetime ...... 2-21 2.5.3 Political Viability and Social Concerns ...... 2-22 2.6 SUMMARY ...... 2-23 2.7 REFERENCES ...... 2-23 3. MISSION AND SYSTEM OVERVIEW...... 3-1 3.1 INTRODUCTION ...... 3-3 3.1.1 Mission Objectives ...... 3-3 3.1.2 Surface Mission Implementation Requirements...... 3-4 3.1.2.1 Conduct Human Missions to Mars ...... 3-4 3.1.2.2 Conduct Applied Science Research ...... 3-5 3.1.2.3 Conduct Basic Science Research ...... 3-6 3.1.2.4 Surface Operations Philosophy...... 3-7 3.1.3 Groundrules and Assumptions ...... 3-11 3.2 RISKS AND RISK MITIGATION STRATEGY ...... 3-12 3.2.1 Risks to Human Life ...... 3-13 3.2.2 Risks to Mission Success ...... 3-14 3.2.3 Risks to Program Success ...... 3-14 3.2.4 Risk Mitigation Strategy ...... 3-14 3.3 FLIGHT CREW ...... 3-16 3.3.1 Crew Composition ...... 3-16 3.3.2 Crew Systems Requirements ...... 3-20 3.4 MISSION OPERATIONS ...... 3-21 3.4.1 Training Guidelines...... 3-22 3.4.2 Science and Exploration ...... 3-24 3.4.3 System Operations and Maintenance...... 3-24 3.4.4 Programmatic Activities ...... 3-25 3.4.5 Activity Planning ...... 3-26 3.4.5.1 Pre-Launch Phase ...... 3-27 3.4.5.2 Earth Launch Phase ...... 3-28 3.4.5.3 Trans-Mars Phase ...... 3-29 3.4.5.4 Mars Landing Phase ...... 3-30 3.4.5.5 Mars Surface Phase ...... 3-31 3.4.5.6 Mars Launch Phase ...... 3-33 3.4.5.7 Trans Earth Phase ...... 3-34 3.4.5.8 Earth Entry and Landing ...... 3-35 3.4.5.9 Post Landing ...... 3-35

X Section Page

3.5 MISSION DESIGN ...... 3-36 3.5.1 Trajectory Options ...... 3-36 3.5.2 Trajectory Selection Factors ...... 3-37 3.5.2.1 Satisfying Reference Mission Goals and Objectives ...... 3-38 3.5.2.2 Satisfying Reference Mission Risk Strategy ...... 3-38 3.5.2.3 Satisfying Reference Mission Program Flexibility ...... 3-41 3.5.3 Mission Design Strategy ...... 3-42 3.5.3.1 Trajectory Type ...... 3-42 3.5.3.2 Split Mission Strategy ...... 3-42 3.5.3.3 Aerocapture ...... 3-43 3.5.3.4 Surface Rendezvous...... 3-43 3.5.3.5 Use of Indigenous Resources ...... 3-44 3.5.3.6 Mars Orbit Rendezvous and Direct Entry at Earth ...... 3-44 3.5.4 Mission Sequence ...... 3-44 3.5.4.1 First Mission: 2007 Opportunity ...... 3-45 3.5.4.2 Second Mission: First Flight Crew, 2009 Opportunity...... 3-46 3.5.4.3 Third Mission: Second Flight Crew, 2011 Opportunity ...... 3-54 3.5.4.4 Fourth Mission: Third Flight Crew, 2014 Opportunity ...... 3-55 3.5.4.5 Mission Summary ...... 3-59 3.6 SYSTEMS ...... 3-60 3.6.1 Operational Design Considerations ...... 3-61 3.6.2 Launch Vehicles ...... 3-62 3.6.3 Interplanetary Transportation ...... 3-72 3.6.3.1 Trans-Mars Injection Stage...... 3-72 3.6.3.2 Biconic Aeroshell ...... 3-73 3.6.3.3 Transit/Surface Habitat ...... 3-77 3.6.3.4 Mars Surface Lander...... 3-79 3.6.3.5 Mars Ascent Vehicle...... 3-82 3.6.3.6 Earth-Return Vehicle...... 3-86 3.6.3.7 Interplanetary Transportation Power Systems ...... 3-90 3.6.4 Surface Systems ...... 3-95 3.6.4.1 Surface Habitat/Laboratory ...... 3-95 3.6.4.2 Life Support System ...... 3-97 3.6.4.3 In-Situ Resource Utilization...... 3-101 3.6.4.4 Surface Mobility ...... 3-105 3.6.4.5 Extra Vehicular Activity Systems ...... 3-110 3.6.4.6 Surface Power Systems ...... 3-111 3.7 PRECURSORS ...... 3-116 3.7.1 Current Robotic Program Plans ...... 3-116 3.7.2 Mars Sample Return With ISRU ...... 3-116 3.7.3 Human Exploration Precursor Needs ...... 3-117 3.7.4 Autonomous Deployment of Surface and Orbital Elements ...... 3-117 3.8 GROUND SUPPORT AND FACILITIES OPERATIONS ...... 3-118 3.8.1 Systems Operations...... 3-120 3.8.2 Science Operations ...... 3-121

XI Section Page

3.9 PROGRAMMATIC ISSUES ...... 3-122 3.9.1 Cost Analysis ...... 3-122 3.9.1.1 Organizational Culture and Cost ...... 3-123 3.9.1.2 The Cost Model ...... 3-124 3.9.2 Management and Organizational Structure ...... 3-132 3.9.3 Technology Development ...... 3-136 3.10 REFERENCES ...... 3-144

TABLES

Table Page

1-1 Pricipal Discriminators of Short- and Long-Stay Mission Scenarios...... 1-29 1-2 Key Elements of Lower-Cost Programs ...... 1-42

2-1 Mars Exploration Consultant Team...... 2-4 2-2 Mars Study Team ...... 2-5

3-1 Capabilities and Demonstrations for Surface Mission Activities ...... 3-5 3-2 Surface Mission Skills ...... 3-18 3-3 General Launch Manifest: 2007 Launch Opportunity ...... 3-47 3-4 General Launch Manifest: 2009 Launch Opportunity ...... 3-49 3-5 Surface Science Payload for First Flight Crew ...... 3-52 3-6 General Launch Manifest: 2011 Launch Opportunity ...... 3-55 3-7 Surface Science Payload for Second Flight Crew ...... 3-57 3-8 General Launch Manifest: 2014 Launch Opportunity ...... 3-59 3-9 Surface Science Payload for Third Flight Crew ...... 3-60 3-10 Launch Vehicle Concepts for the Mars Reference Mission ...... 3-63 3-11 Mass Estimates for TMI Stage Alternatives ...... 3-75 3-12 Mass and Size Estimates for Biconic Aeroshell Family ...... 3-77 3-13 Mars Transit/Surface Habitation Element ...... 3-82 3-14 Earth Return Habitation Element Mass Breakdown ...... 3-92 3-15 Estimated Power Profile for Outbound and Return Transits ...... 3-93 3-16 30kWe Power System With Fuel Cells and Solar Arrays ...... 3-96 3-17 5kWe Power System With Fuel Cells and Solar Arrays ...... 3-96 3-18 Mars Surface Laboratory/Habitat Element Mass Breakdown ...... 3-98 3-19 LSS Mass, Volume, Power Comparison...... 3-100 3-20 Mass and Power Estimates for the First ISRU Plant ...... 3-105 3-21 Mass and Power Estimates for the Second ISRU Plant ...... 3-106 3-22 Characteristics for Fixed Surface Power System Options ...... 3-113 3-23 Rover Power System Characteristics...... 3-115 3-24 Program Environment Effects on Program Management Style ...... 3-126 3-25 A Comparison of Development Culture Parameters for Commercial Aircraft and NASA Manned Programs...... 3-127 3-26 Key Elements of Lower-Cost Programs ...... 3-134 3-27 Dual Use Technologies: Propulsion ...... 3-139 3-28 Dual Use Technologies: Communications/Information Systems...... 3-139

XII Table Page

3-29 Dual Use Technologies: In Situ Resource Utilization...... 3-140 3-30 Dual Use Technologies: Surface Mobility - Suits ...... 3-141 3-31 Dual Use Technologies: Surface Mobility - Vehicles ...... 3-141 3-32 Dual Use Technologies: Human Support ...... 3-142 3-33 Dual Use Technologies: Power...... 3-142 3-34 Dual Use Technologies: Structures and Materials ...... 3-143 3-35 Dual Use Technologies: Science and Science Equipment...... 3-143 3-36 Dual Use Technologies: Operations and Maintenance ...... 3-144

FIGURES

Figure Page

1-1 Typical fast-transit trajectory ...... 1-9 1-2 Mars Reference Mission Sequence...... 1-10 1-3 General sequence of events associated with first mission to Mars ...... 1-11 1-4 Possible time line for first Mars surface mission ...... 1-15 1-5 Reference Mars cargo and piloted vehicles ...... 1-20 1-6 Distribution of Reference Mission costs ...... 1-39 1-7 Relationship between program cost and program culture ...... 1-41

2-1 Orbital image taken by Mariner 4 (1965) ...... 2-7 2-2 Olympus Mons v (Mariner 9 image), the largest volcano in the solar system...... 2-8 2-3 Across the middle is Valles Marineris, a huge canyon as long as the United States...... 2-9 2-4 Dense tributary networks indicative of past presence of liquid water on Mars ...... 2-11

3-1 A regional map illustrating potential locations for a Mars outpost ...... 3-8 3-2 Typical short-stay mission profile...... 3-37 3-3 Typical long-stay mission profile ...... 3-37 3-4 Fast-Transit mission profile ...... 3-38 3-5 Round-trip mission duration comparisons ...... 3-39 3-6 Microgravity comparisons for various mission classes ...... 3-41 3-7 Mars reference mission sequence ...... 3-45 3-8 Mars surface outpost after deployment of payloads from first two cargo landers ...... 3-48 3-9 Mars surface outpost at the end of first flight crew’s stay ...... 3-51 3-10 Possible surface mission time line ...... 3-53 3-11 Mars surface outpost at the end of second flight crew’s stay ...... 3-56 3-12 Mars surface outpost at the end of third flight crew’s stay ...... 3-58 3-13 Mars Energia-derived HLLV with eight Zenit-type boosters...... 3-64 3-14 STS External Tank-derived HLLV with seven LOX/RP boosters ...... 3-65 3-15 STS External Tank-derived HLLV with four strap-on boosters, each having two F-1 engines ...... 3-67 3-16 Saturn V-derived Mars HLLV with F-1A/J-2S propulsion ...... 3-68 3-17 Saturn V-based Mars HLLV concepts ...... 3-69 3-18 Energia launch vehicle adapted to Mars mission profile ...... 3-70

XIII Figure Page

3-19 Mars mission launch vehicle with two external tank boosters and kick stage ...... 3-71 3-20 Reference Mars cargo and piloted vehicles ...... 3-73 3-21 Biconic aeroshell dimensions for Mars lander and surface habitat modules ...... 3-76 3-22 Transit habitat attached to International Space Station ...... 3-78 3-23 The crew exercise facility component of the countermeasures system designed to inhibit crew degradation from exposure to reduced gravity environments ...... 3-80 3-24 EVA suit storage locations are critical in a robust crew safety system ...... 3-80 3-25 Conceptual Mars habitation module-wardroom design ...... 3-81 3-26 Habitat and surface laboratory joined on Mars surface ...... 3-83 3-27 Mars surface lander descending on parachutes ...... 3-84 3-28 Mars surface lander just prior to landing illustrating landing legs and surface mobility system ...... 3-85 3-29 Mars surface lander and biconic aeroshell ...... 3-87 3-30 Crew ascent capsule just after launch from Mars surface ...... 3-87 3-31 Methane/LOX ascent stage configuration2 ...... 3-88 3-32 ECCV returning to Earth on a steerable parafoil...... 3-91 3-33 Solar array power source for interplanetary spacecraft ...... 3-94 3-34 Nominal power profile for the transit/surface habitat ...... 3-95 3-35 Hybrid LSS process distribution ...... 3-100 3-36 Schematic of the first ISRU plant ...... 3-104 3-37 Concepts for the unpressurized and automated surface rovers ...... 3-108 3-38 Concept for the large pressurized surface rover ...... 3-109 3-39 Conceptual airlock and EVA suit maintenance facility ...... 3-111 3-40 Mars surface power profile ...... 3-112 3-41 The relative cost of programs using different management approaches ...... 3-125 3-42 A comparison of the relative costs for Reference Mission elements ...... 3-129

XIV Acronyms

AMCM Advanced Missions Cost Model MTV Mars transfer vehicle

COSPAR Committee on Space Research NASA National Aeronautics and CPAF cost plus award fee Space Administration ND NERVA derived CPFF cost plus fixed fee NDR NERVA derivative reactor DIPS Dynamic Isotope Power System NERVA nuclear engine for rocket vehicle application ECCV Earth crew capture vehicle NTR nuclear thermal rocket ERV Earth return vehicle PI principal investigator ETO Earth-to-orbit PVA photovoltaic array EVA extravehicular activity

RFC regenerative fuel cell GCR galactic cosmic radiation RTG radioisotope thermoelectric generator HMF health maintenance facility SPE solar proton event HLLV heavy-lift launch vehicle SSME Space Shuttle Main Engine IAA International Academy of STS Space Transportation System Astronautics TEI trans-Earth injection IMLEO intial mass to low Earth orbit TCS Thermal Contract System ISRU in-situ resource utilization TMI trans-Mars injection LEO low Earth orbit TROVs telerobotic rovers LMO low Mars orbit LOX liquid oxygen LSS life support system

MAV Mars-ascent vehicle MGS Mars Global Surveyor MOI Mars Orbit Insertion

XV 1. Overview

1-1 1-2 1.1 Introduction Reference Mission, choices have been made. In this report, the rationale for each choice is The human exploration of Mars will be a documented; however, unanticipated complex undertaking. It is an enterprise that technology advances or political decisions will confirm the potential for humans to leave might change the choices in the future. our home planet and make our way outward into the cosmos. Though just a small step on a One principal use of the Reference cosmic scale, it will be a significant one for Mission is to lay the basis for comparing humans, because it will require leaving Earth different approaches and criteria in order to with very limited return capability. The select better ones. Even though the Reference commitment to launch is a commitment to Mission appears to have better technical several years away from Earth, and there is a feasibility, less risk, and lower cost than very narrow window within which return is previous approaches, improvement is still possible. This is the most radical difference needed in these areas to make the first piloted between Mars exploration and previous lunar Mars mission a feasible undertaking for the explorations. spacefaring nations of Earth. The Reference Mission is not implementable in its present Personnel representing several NASA form. It involves assumptions and field centers have formulated a “Reference projections, and it cannot be accomplished Mission” addressing human exploration of without further research, development, and Mars. This report summarizes their work and technology demonstrations. It is also not describes a plan for the first human missions developed in the detail necessary for to Mars, using approaches that are technically implementation, which would require a feasible, have reasonable risks, and have systematic development of requirements relatively low costs. The architecture for the through the system engineering process. With Mars Reference Mission builds on previous this in mind, the Reference Mission may be work, principally on the work of the used to: Synthesis Group (1991) and Zubrin’s (1991) concepts for the use of propellants derived •Derive technology research and from the martian atmosphere. In defining the development plans.

1-3 •Define and prioritize requirements for •The architectural level involves precursor robotic missions. assembly of all elements into an integrated whole. The principal features •Define and prioritize flight experiments to be addressed in a new architecture for precursor human missions, such as that will improve on the Reference those involving the Space Shuttle, Mir, or Mission appear to be simplification the International Space Station. (particularly the number of separate •Understand requirements for human elements that must be developed) and exploration of Mars in the context of integration with other programs. other space missions and research and Simplification by reduction of system development programs, as they are elements can lower life-cycle costs and defined. diminish both programmatic and •Open discussion with international technical risk. For example, the partners in a manner that allows development of higher performance identification of potential interests of the space propulsion systems can lead to participants in specialized aspects of the simplification, particularly if one vehicle missions. can be used for transit to and from Mars. Integration opportunities to link the •Provide educational materials at all Mars program with other development levels that can be used to explain various programs could reduce total cost aspects of human interplanetary through sharing of developmental costs. exploration. The Reference Mission did not assume •Describe to the public, media, and integration with a lunar exploration political system the feasible, long-term program. The development of a major visions for space exploration. Earth-orbiting operations center in another program could lead to major •Establish an end-to-end mission baseline changes in the Reference Mission against which other proposals can be architectural approach. compared. •At the mission level, it may be possible However, the primary purpose of the to reduce the number of separate Reference Mission is to stimulate further launches from Earth. Reducing the total thought and development of alternative number of launches required to approaches which can improve effectiveness, implement the Reference Mission reduce risks, and reduce cost. Improvements objectives could potentially reduce can be made at several levels; for example, in program and technical risk as well as the architectural, mission, and system levels. cost. Focusing and streamlining mission

1-4 objectives and improving technology programmatic and technical requirements that will lower mass and power that would be placed on existing and planned requirements can improve the mission Agency programs. level. In August 1992, the first workshop of the •At the system level, the performance of Mars Study Team held at the Lunar and individual systems and subsystems can Planetary Institute in Houston, Texas, be improved through research and addressed the “whys” of Mars exploration to development programs. The provide the top-level requirements from programmatic and technical risks can be which the Mars exploration program could be reduced by demonstrations of ground, built (Duke and Budden 1992). The workshop Earth-orbit, or planet surface (including attendees identified the major elements of a the Moon) technology. Criteria for potential rationale for a Mars exploration improved systems are principally program as: technical—reduced mass, reduced •Human Evolution – Mars is the most power, increased reliability. accessible planet beyond the Earth-Moon The current section of this report system where sustained human presence provides a brief overview of the origins of the is believed to be possible. The technical study and the Reference Mission design, objectives of Mars exploration should be specifically discussing key issues, findings, to understand what would be required and recommendations. Section 2 of this report to sustain a permanent human presence addresses what can be learned by beyond Earth. undertaking the Reference Mission and •Comparative Planetology – The scientific describes the scientific and technical objectives of Mars exploration should be objectives of Mars exploration. Section 3 to understand the planet and its history, provides a detailed discussion of the mission and therefore to better understand Earth. life cycle, the systems needed to carry it out, and the management challenges and •International Cooperation – The political opportunities that are inherent in a program environment at the end of the Cold War to explore Mars with humans. may be conducive to a concerted international effort that is appropriate to, 1.2 Background and may be required for, a sustained Mars program. The Mars Exploration Study Project was undertaken to establish a vision for the •Technology Advancement – The human human exploration of Mars that would serve exploration of Mars currently lies at the as a mechanism for understanding the ragged edge of achievability. The

1-5 necessary technical capabilities are either •Basic science research to gain new just available or on the horizon. knowledge about the solar system’s Commitment to the program will both origin and history. effectively exploit previous investments The human missions to Mars, which are and contribute to advances in required to accomplish the exploration and technology. research activities, also contain requirements •Inspiration – The goals of Mars for safe transportation, maintenance on the exploration are grand; they will motivate surface of Mars, and return of a healthy crew our youth, benefit technical education to Earth. The surface exploration mission goals, and excite the people and nations envisions approximately equal priority for of the world. applied science research (that is, learning about the environment, resources, and The study team of personnel from NASA operational constraints that would allow field centers used these inputs to construct humans eventually to inhabit the planet) and the Reference Mission, and then translated the basic science research (that is, exploring the inputs into a set of goals and objectives. planet for insights into the nature of planets, Ground rules and assumptions were agreed the nature of Mars’ atmosphere and its upon and reflect the lessons learned from evolution, and the possible past existence of previous study efforts. From this work, a life). These more detailed objectives form the mission and a set of systems were developed. basis for defining the required elements and 1.3 Reference Mission Summary operations for the Reference Mission. In addition, past mission studies have 1.3.1 Objectives yielded results that have characterized piloted Reflecting the conclusions of the August Mars missions as being inherently difficult 1992 workshop, three objectives were adopted and exorbitantly expensive. To confront these for the analysis of a Mars exploration commonly accepted beliefs that are program and the first piloted missions in that unfortunately tied to Mars missions, this program. They are to conduct: study added objectives to:

•Human missions to Mars and verify a •Challenge the notion that the human way that people can ultimately inhabit exploration of Mars is a 30-year program Mars. that will cost hundreds of billions of dollars. Although the nations of the •Applied science research to use Mars world could afford such expenditures in resources to augment life-sustaining comparison to, for example, military systems. budgets, the smaller the total cost, the

1-6 more likely it is that the program will be •Define a robust planetary surface implemented. exploration capacity capable of safely and productively supporting crews on •Challenge the traditional technical the surface of Mars for 500 to 600 days obstacles associated with sending each mission. humans to Mars. •Define a capability to be able to live off •Identify relevant technology the land. development and investment opportunities that benefit both Mars •Rely on advances in automation to exploration and Earth-bound endeavors. perform a significant amount of the routine activities throughout the From these basic objectives, a Reference mission. Mission was crafted by drawing on lessons learned from many past studies and by •Ensure that management techniques are adding new insights to various aspects of the available and can be designed into a mission. This approach substantially program implementation that can improved the yield from piloted missions substantially reduce costs. while also reducing risk and cost. •Use the Earth-Mars launch opportunities occurring from 2007 through 2014. A 1.3.2 Ground Rules and Assumptions 2009 launch represents the most difficult Translating these objectives into specific opportunity in the 15-year Earth-Mars missions and systems for the Reference cycle. By designing the space Mission required adopting a number of transportation systems for this ground rules and assumptions. These were to: opportunity, particularly those systems •Balance technical, programmatic, associated with human flights, they can mission, and safety risks. be flown in any opportunity with either faster transit times for the crew or •Provide an operationally simple mission increased payload delivery capacity. approach emphasizing the judicious use of common systems. •Examine three human missions to Mars. The initial investment to send a human •Provide a flexible implementation crew to Mars is sufficient to warrant strategy. more than one or two missions. Each •Limit the length of time that the crew is mission will return to the site of the continuously exposed to the initial mission thus permitting an interplanetary space environment. evolutionary establishment of capabilities on the Mars surface.

1-7 Although it is arguable that scientific significantly challenge the management and data return could be enhanced by a operations systems to support the crew in the strategy where each human mission new situations. went to a different surface site, the goal of understanding how humans can 1.3.3.1 Mission Design inhabit Mars seems more logically The crew will travel to and from Mars on directed toward a single outpost relatively fast transits (4 to 6 months) and will approach. spend long periods of time (18 to 20 months; 600 days nominal) on the surface, rather than 1.3.3 Mission and Systems alternative approaches which require longer Previous studies of human exploration of times in space and reduce time on the surface. Mars have tended to focus on spacecraft and Figure 1-1 illustrates a typical trajectory. flight, rather than on what the crew would do Designed to the worst-case mission on the surface. The Reference Mission takes opportunity (2007-2009) of the next two the point of view that surface exploration is decades, the transit legs are less than 180 days the key to the mission, both for science and in both directions. For easier Mars mission for evaluation of the potential for settlement. opportunities (for example, 2016-2018), the As a consequence, the Reference Mission transit legs are on the order of 130 days. architecture allows for a robust surface Shorter transit times reduce the time spent by capability with significant performance the crew in zero g to the length of typical margins: Crews will explore in the vicinity of tours of duty for the International Space the outpost out to a few hundred kilometers, Station. (Thus, the Mars Study Team chose will be able to study materials in situ and in a not to use artificial gravity spacecraft designs surface laboratory, and will be allowed to for the Reference Mission.) In addition, update and modify the exploration plan to relatively fast transits will reduce the take advantage of their discoveries. exposure to galactic cosmic radiation and the probability of encountering solar particle In addition, key technologies will be events. Reducing the exposure to zero g and developed and demonstrated to test radiation events helps reduce the risk to the settlement issues, potentially imposing a crew. substantial workload on the Mars exploration crew. To improve the effectiveness of surface The strategy chosen for the Reference operations, supporting systems must be Mission, generally known as a “split mission” highly reliable, highly autonomous, and strategy, breaks mission elements into pieces highly responsive to the needs of the crew. that can be launched directly from Earth with Some needs may not be anticipated during launch vehicles of the Saturn V or Energia crew preparation and training, which will class, without rendezvous or assembly in low

1-8 Earth orbit (LEO). The strategy has these MISSION TIMES pieces rendezvous on the surface of Mars, OUTBOUND 150 days Earth Launch STAY 619 days which will require both accurate landing and 2/1/2014 RETURN 110 days Depart Mars mobility of major elements on the surface to 3/11/2016 TOTAL MISSION 879 days allow them to be connected or to be moved into close proximity. Another attribute of the γ split mission strategy is that it allows cargo to Nominal be sent to Mars without a crew during the Departure Earth Return 3/11/2016 6/29/2016 same launch opportunity or even one or more opportunities prior to crew departure. This Arrive Mars allows cargo to be transferred on low energy, 7/1/2014 longer transit time trajectories and the crew to be sent on a required higher energy, shorter Figure 1-1 Typical fast-transit transit time trajectory. Breaking the mission trajectory. into two launch windows allows much of the infrastructure to be emplaced and checked sequence gradually builds up assets on the out before committing a crew to the mission, martian surface so that at the end of the third and also allows for a robust capability, with crew’s tour of duty, the basic infrastructure duplicate launches on subsequent missions could be in place to support a permanent providing either backup for the earlier presence on Mars. launches or growth of initial capability. The six launches used to support the Figure 1-2 illustrates the mission activities of the first crew will be discussed in sequence analyzed for the Reference Mission. more detail here to illustrate what will In this sequence, three vehicles will be typically occur for all three crews. (Note: For launched from Earth to Mars in each of four the nominal mission, launches 1 through 4 are launch opportunities which, for reasons required to support the first crew; launches 5 presented earlier, start in 2007. The first three and 6 provide backup systems for the first launches will not involve a crew but will send crew and, if not used, are available for the infrastructure elements to low Mars orbit and second crew.) Figure 1-3 illustrates the to the surface for later use. Each of the general sequence of events associated with remaining opportunities analyzed for the the first crew’s mission to Mars as discussed Reference Mission will send one crew and in the following paragraphs. two cargo missions to Mars. These cargo missions will consist of an Earth-return In the first launch opportunity, three vehicle (ERV) on one flight and a lander cargo missions are sent on minimum energy carrying a Mars-ascent vehicle (MAV) and trajectories direct to Mars (that is, without additional supplies on the second. This assembly or fueling in LEO). Launch 1

1-9 delivers a fully fueled ERV to Mars orbit. (The approximately 40 tonnes of additional crew will rendezvous with this stage and use payload to the surface. After the descent stage it to return to Earth after completion of their lands on the surface, the nuclear reactor surface exploration mission.) Launch 2 autonomously deploys itself several hundred delivers an unfueled MAV, a propellant meters from the ascent vehicle. Using the production module, a nuclear power plant, Mars atmosphere as feedstock, the propellant liquid hydrogen (to be used as a reactant to production module begins to manufacture the produce the ascent vehicle propellant), and nearly 30 tonnes of oxygen and methane that

ETO FLIGHT 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 ERV loiter ∆ Crew 1 TEI 1 ∆ ERV-1 parks in LMO ∆ Crew 1 Earth return 2 ∆ MAV-1 landing

3 ∆ Initial Habitat landing

6 Crew 1: launch ∆ ∆ Landing ∆ Crew 1 ascent ERV loiter ∆ Crew 2 TEI 4 ∆ ∆ ERV-2 parks in LMO Crew 2 Earth return

5 ∆ MAV-2 landing

9 Crew 2 launch ∆ ∆ Landing ∆ Crew 2 ascent ERV loiter ∆ Crew 3 TEI 7 ∆ ERV-3 parks in LMO ∆ Crew 3 Earth return

8 ∆ MAV 3 landing

12 Crew 3 launch ∆ ∆ Landing ∆ Ascent ERV loiter 10 ∆ ERV 4 LMO 11 ∆ MAV 4 landing

Interplanetary transit ERV: Earth Return Vehicle

12345678901 12345678901 MAV: Mars Ascent Vehicle 12345678901 Unoccupied wait in Mars orbit

12345678 TEI: Trans Earth Injection 12345678Propellant production and on Mars surface LMO: Low Mars Orbit Crew surface operations

Figure 1-2 Mars Reference Mission sequence.

1-10 Figure 1-3 General sequence of events associated with first mission to Mars.

1-11 Figure 1-3 General sequence of events continued.

1-12 will be required to eventually deliver the crew similarly mirrors Launch 2 of the previous to Mars orbit. This production is completed opportunity, delivering a second unfueled within approximately one year—several ascent vehicle and propellant production months prior to the first crew’s scheduled module. These systems provide backup or departure from Earth. Launch 3 lands in the extensions of the previously deployed vicinity of the first descent vehicle and capabilities. For example, the second MAV delivers a surface habitat/laboratory, and second ERV provide the first crew with nonperishable consumables for a safe-haven, two redundant means for each leg of the and a second nuclear power plant to the return trip. If, for some reason, either the first planetary surface. The second nuclear power ascent vehicle or the first return vehicle plant autonomously deploys itself near the becomes inoperable after the first crew first power plant. Each power plant can departs Earth, this crew can use either of the provide sufficient power (160 kWe) for the systems launched in the second opportunity entire mature surface outpost, thereby instead. If the first ascent and return vehicles providing complete redundancy within the operate as expected, then the systems power production function. delivered in the second opportunity will support the second crew that will launch to During the second launch opportunity, Mars in the third opportunity. two additional cargo missions and the first crew are launched. All assets previously The first crew of six departs for Mars in delivered to Mars have been checked out and the second opportunity. They leave Earth the MAV, already on the martian surface, is after the two cargo missions have been verified to be fully fueled before either the launched, but because they are sent on a fast crew or the additional cargo missions are transfer trajectory of only 180 days, they will launched from Earth. (Should any element of arrive in Mars orbit approximately 2 months the surface system required for crew safety or before the cargo missions. The crew lands on critical for mission success not check out Mars in a surface habitat substantially adequately, the surface systems will be placed identical to the habitat/laboratory previously in standby mode and the crew mission deployed on the martian surface. After delayed until the systems can be replaced or capturing into a highly elliptic Mars orbit, the their functions restored. Some systems can be crew descends in the transit habitat to replaced using hardware originally intended rendezvous on the surface with the other for subsequent missions; others may be elements of the surface outpost. (The crew functionally replaced by other systems.) The carries sufficient provisions for the entire first cargo launch of this second opportunity surface stay in the unlikely event that they are is a duplicate of Launch 1 from the first unable to rendezvous on the surface with the opportunity, delivering a second fully fueled assets previously deployed.) ERV to Mars orbit. The second cargo launch

1-13 Surface exploration by robotic vehicles Mars. The purpose of these studies would be and human explorers will include a wide to support the field investigations, answer range of activities. “sharper” questions, and allow the human explorers to narrow their focus to the sites of •Observing and analyzing the surface and optimum sample collection. As hypotheses subsurface geology. evolve, crews will be able to return to sample •Observing and analyzing the sites and gather specific samples to test the composition and structure of the hypotheses. Ultimately, selected samples will atmosphere. be returned to Earth for more detailed •Collecting samples and examining them analysis. in the outpost laboratory. As experience grows, the range of human •Performing experiments designed to exploration will grow from the local to the gauge the ability of humans to inhabit regional. Regional expeditions, lasting Mars. perhaps 2 weeks and using mobile facilities, may be conducted at intervals of a few Prior to the arrival of the first human months. Between these explorations, analysis crew, telerobotic rovers (TROVs) may be in the laboratory will continue. The crew will delivered to the surface. (These rovers are also spend a significant portion of its time assumed to be intelligent enough to perform performing maintenance and housekeeping broadly stated objectives without human tasks (system design requirements addressing assistance. But humans will continue to enhanced reliability and maintainability will monitor progress and be available to help keep these activities to a minimum). “supervise” the TROV if it cannot solve a Figure 1-4 provides a possible time line for particular problem.) When the crew arrives, the first surface mission. the rovers will be available for teleoperation by the crew. The TROVs may be designed to The deployment of a bioregenerative life provide global access and may be able to support capability will be an early activity return samples to the outpost from hundreds after crew landing. Although this system is of kilometers distance from the site if they are not required to maintain the health and deployed 2 years before the crew arrives. vitality of the crew, it will improve the robustness of the life support system and is The outpost laboratory will be outfitted important to the early objectives of the to provide mineralogical and chemical outpost. analyses of rocks, soils, and atmospheric samples; and depending on technical Crew activities related to living on development, it may be possible to undertake another planet should be viewed as simple kinds of geochronologic analysis on experiments. With minor modifications in

1-14 Mars Surface Mission Time Allocation

(Total Time = 8 crew X 24 hr/day X 600 days = 115,200 hr)

8 crew X 24 hr day = 200)

Personal Hr/Over 14 hr head Production (total 67,200 hr) 7 hr 3 hr (33,600 hr total) (14,400 hr)

Site Prep, Construction 90 days Verification Week Off 7 days Local Excursions

Analysis 100 days Distant Excursion 10 days Analysis 40 days Week Off 7 days Charge Fuel Cells Distant Excursion Check Vehicle Analysis Load Vehicle Plan Excursion Distant Excursion Drive Vehicle Analysis Navigate Don Suits (X 20) Week Off Pre-breathe (X 20) Egress (X 20) Distant Excursion 100 days Unload Equip Recreation, Exercise, Relaxation: 1 hr One Day Off Per Week: 3 hr (per day) Eating, Meal Prep, Clean-up: 1 hr Analysis Set up Drill (X 10) Sleep, Sleep Prep, Dress, Undress: 8 hr Operate Drill Distant Excursion

600 day (or 20 months, or 86 weeks) Collect Samples Hygiene, Cleaning, Personal Communication: 1 hr Analysis In Situ Analysis Take Photos Flare Retreat 15 days Communicate Week Off 7 days Disassemble Equip System Monitoring, Inspection, Calibration, Maintenance, Repair: 1 hr Load Vehicle Distant Excursion Ingress (X 20)

General Planning, Reporting, Documentation, Earth Communication: 1 hr Analysis Clean Suit (X 20) Stow Suit, Equip Distant Excursion Group Socialization, Meetings, Life Sciences Subject, Health Monitoring, Care: 1 hr 100 days Inspect Vehicle Analysis Secure for night (Sleep, eat, cleanup Week Off 7 days hygiene, etc. Sys Shutdown covered) Departure Prep 60 days 3 Crew X 7 hr X 10 Day = 210 hrs total

Figure 1-4 Possible time line for first Mars surface mission.

1-15 hardware and software, ordinary experiences emplaced, checked out, and operated to can be used to provide objective databases for produce the required propellant prior to understanding the requirements for human launching the crew from Earth. settlement. In addition to spacecraft propulsion, the The first crew will stay at the outpost for production capability on Mars can provide 18 to 20 months. Part of their duties will be to fuel for surface transportation, reactants for prepare the outpost site for the receipt of fuel cells, and backup caches of consumables additional elements launched on subsequent (water, oxygen, nitrogen, and argon) for the mission opportunities. Since the first crew life support system. will have to depart before the second crew arrives, some systems will have to be placed 1.3.3.3 Flight Crew in standby mode. Humans are the most valuable mission After their stay on Mars, each crew will asset for Mars exploration and must not use the previously landed and in situ- become the weak link. The objective for resource-utilization fueled ascent vehicle to humans to spend up to 600 days on the return to orbit where they will rendezvous martian surface places unprecedented with the waiting ERV. The crew will return to requirements on the people and their Earth in a habitat similar to the one used for supporting systems. Once committed to the the outbound transit leg. This habitat, which mission on launch from LEO, the crew must is part of the ERV deployed in a previous be prepared to complete the full mission opportunity by one of the cargo flights, without further resupply from Earth. typically will have been in an untended mode Unlimited resources cannot be provided for nearly 4 years prior to the crew arrival. within the constraints of budgets and mission performance. Their resources will either be 1.3.3.2 In Situ Resource Production with them or will have already been delivered to or produced on Mars. So trade-offs must be The highly automated production of made between cost and comfort, as well as propellant from martian resources is another performance and risk. Crew self-sufficiency is defining attribute of the Reference Mission. required because of the long duration of their The technology for producing methane and mission and the fact that their distance from liquid oxygen from the martian atmosphere Earth impedes or makes impossible the and some nominal hydrogen feedstock from traditional level of communications and Earth is an effective performance support by controllers on Earth. The crews enhancement and appears to be will need their own skills and training and technologically feasible within the next few specialized support systems to meet the new years. The split mission strategy allows the challenges of the missions. propellant production capability to be

1-16 The nominal crew size for this mission is Mission objectives. The site must be six. This number is believed to be reasonable consistent with operational considerations, from the point of view of past studies and such as landing and surface operational experience and is a starting point for study. safety. Detailed maps of candidate landing Considerable effort will be required to sites built from data gathered by precursor determine absolute requirements for crew robotic missions will define the safety and size and composition. This determination will operational hazards of the sites, as well as have to consider the tasks required of the confirm whether access to scientifically crew, safety and risk considerations, and the interesting locations is possible by humans or dynamics of an international crew. Crew robotic vehicles. Robotic surface missions, members should be selected in part based on including missions to return samples, may be their ability to relate their experiences back to required to confirm remotely sensed data Earth in an articulate and interesting manner, from orbit and to satisfy planetary protection and they should be given enough free time to issues. To satisfy the human habitation appreciate the experience and the opportunity objectives in particular, it would be highly to be the first explorers of another planet. desirable to locate the outpost site where Significant crew training will be required to water can be readily extracted from minerals ensure that the crew remains productive or from subsurface ice deposits. Such a throughout the mission. determination may only be possible from data collected by a robotic surface mission. 1.3.3.4 Robotic Precursors To accomplish the Reference Mission, key Robotic precursor missions will play a advances in certain critical technologies will significant role in three important areas of the need to occur. The robotic precursor missions Reference Mission. The first area is to gather offer an opportunity to demonstrate the information about Mars that will be used to operation of many of those technologies, such determine what specific crew activities will be as in situ resource utilization, aerocapture, performed and where they will be performed. precision landing, etc. The information and The second area is to demonstrate the experience gained from the demonstration of operation of key techonologies required for these technologies will add immeasurable the Reference Mission. The third is to land, confidence for their use in the human deploy, operate, and maintain a significant mission. portion of the surface systems prior to the The first phase of human exploration is arrival of the crew. the automated landing of surface For optimum mission performance, it infrastructure elements, including a system to will be necessary to pick a landing site based produce propellant and life support primarily on its ability to achieve Reference consumables, the first of two habitats, power

1-17 systems, and surface transportation elements. depart for Mars. To avoid the boiloff loss of All of these systems will be delivered, set up, cryogenic propellants in the departure stages, and checked out using robotic systems all elements must be launched from Earth in operated or supervised from Earth. The quick succession. This places a strain on a propellant required for the MAV will be single launch facility and its ground produced and stored as will oxygen and operations crews or requires the close water caches for the habitat. The overall site coordination of two or more launch facilities. will be prepared for receipt of the second Assembling the Mars vehicles in orbit and habitat. loading them with propellants from an orbiting depot just prior to departure may 1.3.3.5 Launch Systems alleviate the strain on the launch facilities, but The scale of the required Earth-to-orbit the best Earth orbit for a Mars mission is (ETO) launch capability is determined by the different for each launch opportunity. mass of the largest payload intended for the Therefore, a permanent construction or martian surface. The nominal design mass for propellant storage facility in a single Earth individual packages to be landed on Mars in orbit is not an optimal solution. the Reference Mission is 50 tonnes for a crew The choice of a launch vehicle remains a habitat sized for six people that is transferred significant issue for any Mars mission. For the on a high-energy orbit. This requires the Reference Mission, however, the larger, 200- capability for a single launch vehicle to be ton-class launch vehicle has been assumed from about 200 to 225 tonnes to LEO. without specifying a particular configuration. Because 200-ton-class launch vehicles 1.3.3.6 Interplanetary Transportation System raise development cost issues, consideration was given to the option of launching pieces to The interplanetary transportation system LEO using smaller vehicles and assembling consists of a trans-Mars injection (TMI) stage, (attaching) them in space prior to launching a biconic aeroshell for Mars orbit capture and them to Mars. This smaller launch vehicle Mars entry, a descent stage for surface (110 to 120 tonnes) would have the advantage delivery, an ascent stage for crew return to of more modest development costs and is Mars orbit, an Earth-return stage for within the capability of the Russian Energia departure from the Mars system, and a crew program. However, the smaller launch vehicle capsule (similar to an Apollo Command introduces several potential difficulties to the Module) for Earth entry and landing. As Reference Mission scenario. The simplest, mentioned earlier, the Reference Mission most desirable implementation using this splits the delivery of elements to Mars into smaller launch vehicle is to simply dock the cargo missions and human missions, all of two elements in Earth orbit and immediately which are targeted to the same locale on the

1-18 surface and must be landed in close proximity between the NDR engine assembly and the to one another. The transportation strategy LH2 tank to protect the crew from radiation adopted in the Reference Mission eliminates that builds up in the engines during the TMI the need for assembly or rendezvous of burns. Although it may seem wasteful to vehicle elements in LEO, but it does require a discard the nuclear stage after one use, the rendezvous in Mars orbit for the crew leaving complexity of Mars orbit insertion and Mars. The transportation strategy also rendezvous operations for the return flight emphasizes the use of common elements to are avoided. avoid excessive development costs and to As shown in Figure 1-5, the same TMI provide operational simplicity. stage is used in all cargo missions, which The TMI stage (used to propel the allows the transportation system to deliver spacecraft from LEO onto a trans-Mars approximately 65 tonnes of useful cargo to the trajectory) employs nuclear thermal surface of Mars or nearly 100 tonnes to Mars propulsion. Nuclear thermal propulsion was orbit (250 × 33,793 km) on a single launch adopted for the TMI burn because of its from Earth. The TMI stage for cargo delivery performance advantages; its advanced, requires the use of only three NDR engines, previously demonstrated state of technology so one NDR engine and the shadow shield are development; its operational flexibility; and removed from the TMI stage, which reduces its inherent mission enhancements. A single cost and improves performance. TMI stage was developed for both piloted Mars orbit capture and the majority of and cargo missions. The stage is designed for the Mars descent maneuver is performed the more energetically demanding 2009 fast using a single biconic aeroshell. The decision transit trajectory and then used in the to perform the Mars orbit capture maneuver minimum energy cargo missions to carry the was based on the facts that (1) an aeroshell maximum payload possible to Mars. In the will be required to perform the Mars descent human missions, the TMI stage uses four maneuver no matter what method is used to 15,000 lb. thrust NERVA (Nuclear Engine for capture into Mars orbit, (2) the additional Rocket Vehicle Application)-derivative reactor demands on a descent aeroshell to meet the (NDR) engines (Isp = 900 seconds) to deliver Mars capture requirements were determined the crew and the surface habitat/descent to be modest, and (3) a single aeroshell stage onto the trans-Mars trajectory eliminated one staging event, and thus one (Borowski, et al., 1993). After completion of more potential failure mode, prior to landing the two-perigee-burn Earth departure, the on the surface. TMI stage is inserted into a trajectory that will not reencounter Earth or Mars over the course The crew is transported to Mars in a of one million years. The TMI stage used with habitat that is fundamentally identical to the the crew incorporates a shadow shield

1-19 2 10 m 86.0 t LH (@ 100%) 2009 Piloted Mission 1 Surface Hab with Crew and Lander 16.3 m 2 TEIS & Hab 4 10 m 7.6 m 86.0 t LH (@ 192.9%) 2007 Cargo Mission 3 LOX/CH 19.0 m 2 10 m 86.0 t LH (@ 100%) 2007 Cargo Mission 2 Hab Module & Lander (@ 18.2 m length) sized 16.3 m 2 Figure 1-5 Reference Mars cargo and piloted vehicles. 1-5 Reference Figure 2 10 m 216.6T 204.7T 212.1T 86.0 t LH (@ 100%) "Expandabe TMI Stage LH by 2009 Mars Piloted Mission 2007 Cargo Mission 1 "Dry" Ascent Stage & Lander 4.7 m 15.0 m 20.6 m* IMEO = 216.6T

1-20 surface habitat deployed robotically on a been assumed to reduce the descent vehicle’s previous cargo mission. By designing the speed after the aeroshell has ceased to be habitat so that it can be used during transit effective and prior to the final propulsive and on the surface, a number of advantages to maneuver. The selection of LOX/CH4 allows the overall mission are obtained. a common engine to be developed for use by both the descent stage and the ascent stage, •Two habitats provide redundancy on the the latter of which is constrained by the surface during the longest phase of the propellant that is manufactured on the mission. surface using indigenous materials. •By landing in a fully functional habitat, The ascent vehicle is delivered to the the crew does not need to transfer from a Mars surface atop a cargo descent stage. It is “space-only” habitat to the surface composed of an ascent stage and an ascent habitat immediately after landing, which crew capsule. The ascent stage is delivered to allows the crew to readapt to a gravity Mars with its propellant tanks empty. environment at their own pace. However, the descent stage delivering the •The program is required to develop only ascent vehicle includes several tanks of seed one habitat system. The habitat design is hydrogen for use in producing the based on its requirement for surface approximately 30 tonnes of LOX/CH4 utilization. Modifications needed to propellant for the nearly 5,600 meters per adapt it to a zero-g environment must be second delta-V required for ascent to orbit minimized. and rendezvous with the ERV. The ascent A common descent stage has been vehicle uses two RL10-class engines modified assumed for the delivery of the transit/ to burn LOX/CH4. surface habitats, the ascent vehicle, and other The ERV is composed of the trans-Earth surface cargo. The descent vehicle is capable injection (TEI) stage, the Earth-return transit of landing approximately 65 tonnes of cargo habitat, and a capsule the crew will use to on the Mars surface. The landing vehicle is reenter the Earth’s atmosphere. The TEI stage somewhat oversized to deliver crew; is delivered to Mars orbit fully fueled, where however, design of a scaled-down lander and it waits for nearly 4 years before the crew uses the additional associated costs are avoided To it to return to Earth. It uses two RL10-class perform the postaerocapture circularization engines modified to burn LOX/CH4. These burn and the final approximately 500 meters are the same engines developed for the ascent per second of descent prior to landing on the and descent stages, thereby reducing engine Mars surface, the common descent stage development costs and improving employs four RL10-class engines modified to maintainability. The return habitat is a burn LOX/CH4. The use of parachutes has duplicate of the outbound transit/surface

1-21 habitat used by the crew to go to Mars, but approximately 30 percent of the power contains consumables for the return trip only generated in space. For emergency situations, and minimizes crew accommodations the pressurized rover’s Dynamic Isotope required for the surface mission. Power System can supply 10 kWe of continuous power. 1.3.3.7 Surface Systems From a series of volume, mass, and The provision of adequate amounts of mission analyses, a common habitat structural electrical power is fundamental to a cylinder, 7.5 meters in diameter, bilevel, and successful exploration program. For the vertically oriented, was derived for the transit phase, the need for power is less Reference Mission. The three habitation severe than on the martian surface. Solar element types identified for the Reference energy is available for crew needs throughout Mission (the surface laboratory, the transit/ the cruise phase (the transit phase both to and surface habitation element, and the Earth- from Mars). return habitation element) will contain The selection of a power systems strategy substantially identical primary and secondary for surface operations is guided by risk structures, windows, hatches, docking considerations, which require two-level mechanisms, power distribution systems, life redundancy for mission-critical functions and support, environmental control, safety three-level redundancy for life-critical features, stowage, waste management, functions. The surface power systems should communications, airlock function, and crew have 15+ year lifetimes to allow them to serve egress routes. The following are brief the three mission opportunities with good descriptions of the unique aspects of the three safety margins. Surface transportation power primary habitation elements developed for systems should have 6+ year lifetimes to the Reference Mission analysis. minimize the need for replacement over the •The Mars surface laboratory, sent out, program lifetime. landed, and verified prior to the launch The strategy adopted for the Reference of any crew members, will operate only Mission includes a primary and backup in 3/8 gravity. It contains a large, nuclear reactor with dynamic energy nonsensitive (that is, no special conversion. Each system is capable of environmental control required) stowage producing 160 kWe. Additionally, each habitat area with crew support elements on one retains the solar arrays used during transit, level and the primary science and and they can also be operated on the martian research lab on the second level. Future surface. Due to several factors (for example, development of this element includes the presence of an atmosphere, a day-night possible retrofitting of the stowage level cycle, etc.) each power system can produce into a greenhouse as consumables and

1-22 resources are consumed and free volume field work, sample collection, and is created. deployment, operation, and maintenance of instruments. •The Mars transit/surface habitats contain the required consumables for the Mobility on several scales is required by Mars transit and surface duration of people operating from the Mars outpost. approximately 800 days (180 days in Crew members outside the habitat will be in transit and 600 days on the surface) as pressure suits and will be able to operate at well as all the required equipment for some distance from the habitat, determined the crew during the 180-day transfer by their capability to walk back to the trip. This is the critical element that must outpost. They may be served by a variety of effectively operate in both zero and tools, including rovers, carts, and wagons. On partial gravity. Once on the surface of a local scale, perhaps 1 to 10 kilometers from Mars, this element will be physically the outpost, exploration will be implemented connected with the previously landed by unpressurized wheeled vehicles. Beyond surface lab thereby doubling the the safe range for exploration on foot, pressurized volume for the crew. exploration will be in pressurized rovers, Eventually, all four habitation elements allowing explorers to operate for the most (the surface laboratory and three transit/ part in a shirtsleeve environment. surface habitats) will be interconnected. The requirements for long-range surface •The Earth-return habitat, functioning rovers include having a radius of operation of only in zero g and requiring the least up to 500 km in exploration sorties that allow amount of volume for consumables, will 10 workdays to be spent at a particular be volume rich but must be mass remote site, and having sufficient speed to constrained to meet the limitations of the ensure that less than half of the excursion TEI stage. Since little activity (other than time is used for travel. Each day, up to 16 conditioning for the one-g environment person-hours would be available for EVAs. on Earth and training for the Earth- The rover is assumed to have a nominal crew return maneuvers) is projected for the of two people, but be capable of carrying four crew during this phase of the mission, in an emergency. Normally, the rover would mass and radiation protection were the be operated (maneuvering from site to site, key concerns in the internal architecture transmitting high data rate communications, concepts created. supporting EVA activities, etc.) only in the daytime, but could conduct selected Extravehicular activity (EVA) tasks investigations at night. consist of maintaining the habitats and surface facilities and conducting a scientific exploration program encompassing geologic

1-23 1.3.3.8 Operations flight crews can execute all activities which lead to the accomplishment of mission Previous space missions have generally objectives. All crew activities throughout each cost more to operate than to design and mission, from prelaunch through postlanding, construct. This phenomenon was caused constitute crew operations and as such are partly by the fact that systems were designed essential to the overall program. To enhance first and operations were developed to fit the program success, they must be factored into designs. The Reference Mission attempts to all aspects of program planning. The majority bring operational considerations into the of crew activities fall into one of four process early to better balance the cost of categories: training, science and exploration, design and development with the cost of systems operations and maintenance, and operations. programmatics.

1.3.3.8.1 Crew Operations •Training includes activities such as The principal difference between Mars development of training programs, exploration and previous space ventures is development of training facilities and the requirement for crew operations in an hardware, prelaunch survival training environment where on-call communications, for all critical life support systems, assistance, and advice from ground operational and maintenance training on controllers is not available in emergencies due mission-critical hardware, prelaunch and to the communications delay. This leads to a in-flight proficiency training for critical set of operations requirements that: mission phases, and science and research training for accomplishing primary •The crew be able to perform science and exploration objectives. autonomously for time-critical portions of the mission. •The majority of science and exploration activities will be accomplished on the •Highly reliable, autonomous system surface of Mars and will include, but not operations be possible without intensive be limited to, operating TROVs, crew participation. habitability exercises, local and regional •A balance be struck between ground sorties, and planetary science control and the crew on Mars which investigations. Supplemental science optimizes the crew’s time and objectives may be accomplished during effectiveness yet maintains their other phases of the mission as well but independence and motivation to attain will be limited by the mass available for mission objectives. onboard science equipment. Those activities required for crew health and Thus, the Reference Mission will be safety (such as medical checks during successful to the degree that ground and

1-24 transit phases, monitoring solar activities before each crew leaves Earth. However, for flares, etc.) will be performed. once on the surface of Mars, the very nature of the work done by the crews •During the first mission, a substantial will require real-time activity planning amount of crew time will be devoted to to take advantage of discoveries made as the operation and maintenance of the mission progresses. vehicle systems. This time is expected to decrease during subsequent missions as No specific conclusions regarding both the systems and operational hardware requirements, facilities experience bases mature. However, requirements, training programs, and the like maximizing the crew’s useful science were derived for this study. But a number of and exploration time will increase recommendations and guidelines regarding overall mission effectiveness, and the these areas have been developed and tailored systems or procedures which contribute to the various mission phases that will be to increasing this time and decreasing experienced by each crew sent to Mars. While routine operations and maintenance will these and other crew activities may not be be incorporated wherever possible. seen as directly affecting program success, all areas contribute to the successful execution of •Lastly, programmatic activities for flight each mission and, therefore, are essential to crews will include public relations, the overall success of the Reference Mission. documentation, reporting, and real-time activity planning. Public relations 1.3.3.8.2 Earth-Based Support activities have been and always will be an integral part of crew activities. While The overall goal of Earth-based support these activities absorb resources, the operations is to provide a framework for most significant of which is time, they planning, managing, and conducting also bring public and political support to activities which achieve mission objectives. the program and provide some of the Achieving this operational goal requires return on investment of the program. successful accomplishment of the following Throughout all mission phases, functions. documentation of activities and feedback •Safe and efficient operation of all on training effectiveness will be required resources. This includes, but is not of all crews. This will be essential to limited to, vehicles, support facilities, make effective use of the follow-on training facilities, scientific and systems crew’s training time and the program’s data, and personnel knowledge and training hardware and facilities. Many of experience bases. the mission-critical activities will be planned and rehearsed in great detail

1-25 •Provision of the facilities and an managing and monitoring operations environment which allow users (such as planning and execution while crew members scientists, payload specialists, and to an will be assigned the actual responsibility for extent crew members) to conduct operations planning and execution. Crew activities that will enhance the mission members will be told what tasks to do or objectives. what objectives to accomplish, but not how to do it. This has the benefit of involving system •Successful management and operation of and payloads experts in the overall planning, the overall program and supporting yet giving crews the flexibility to execute the organizations. This requires defining tasks. The proposed method for the Reference roles and responsibilities and Mission would take advantage of the unique establishing a path of authority. Program perspective of crew members in a new and mission goals and objectives must environment but would not restrict their be outlined so that management activities because of the mission’s remote responsibilities are clear and direct. nature. Additionally, it places the Confusing or conflicting objectives can responsibility of mission success with the result in loss of resources, the most crew, while the overall responsibility for important of which are time and money. prioritizing activities in support of mission In addition, minimizing the number of objectives resides with Earth-based support. layers of authority will help to prevent operational decision-making activities After dividing functional responsibilities from being prolonged. between Earth-based support and crew, the support may be structured to manage the The Reference Mission, while large and appropriate functions. To accomplish mission complex, has the added complication of being objectives while maintaining the first a program with mission phases which cannot operational objective of safe and efficient be supported with near real-time operations. operation of all resources, Earth-based Planetary surface operations pose unique support can be organizationally separated operational considerations on the into systems operations and science organization of ground support and facilities. operations provided a well-defined interface A move toward autonomy in vehicle exists between the two. The systems operations, failure recognition and resolution, operations team would be responsible for and mission planning is needed. And ground conducting the safe and efficient operation of support must be structured to support these all resources, while the science operations needs. team would be responsible for conducting In general, due to the uniqueness of activities which support scientific research. planetary surface operations, Earth-based Such an organizational structure would support should be assigned the role of

1-26 dictate two separate operations teams with the overall operations manager should reside distinct priorities and responsibilities yet the within systems operations. A science same operational goal. operations manager, who heads the science operations team, should organizationally be Systems operations are those tasks which in support of the operations manager. Various keep elements of the program in operational levels of interfaces between systems engineers condition and support productive utilization and science team members must exist to of program resources. Thus, the systems maximize the amount of science and mission operations team has responsibility for objectives that can be accomplished. conducting the safe and efficient operation of all such resources. The systems operations 1.3.3.9 Mission and Systems Summary team consists of representatives from each of the primary systems (power, propulsion, To summarize, the major distinguishing environmental, electrical, etc.) which are used characteristics of the Reference Mission throughout the various mission phases. include:

The science operations team’s sole •No extended LEO operations, assembly, function is to recommend, organize, and aid or fueling. in conducting all activities which support •No rendezvous in Mars orbit prior to scientific research within the guidelines of the landing. mission objectives. The team will consist of •Short crew transit times to and from representatives from the various science Mars (180 days or less) and long surface disciplines (biology, medicine, astronomy, stay-times (500 to 600 days) for the first geology, atmospherics, etc.) which support and all subsequent crews exploring the science and mission objectives. Each Mars. scientific discipline will have an appropriate support team of personnel from government, •A heavy lift launch vehicle capable of industry, and academia who have expertise in transporting either crew or cargo direct that field. The science operations team will act to Mars, and capable of delivering in as the decision-making body for all science four launches all needed payload for the activities—from determining which activities first human mission and in three have highest priority to handling and launches for each subsequent disseminating scientific data. opportunity.

Crew and vehicle safety are always of •Exploitation of indigenous resources primary concern. When those are ensured, from the beginning of the program, with science activities become the highest priority. important performance benefits and To accommodate this hierarchy of priorities reduction of mission risk. within the operations management structure,

1-27 •Availability of abort-to-Mars surface Two different approaches have been strategies, based on the robustness of the proposed in the past. The first is comparable Mars surface capabilities and the cost of to the Reference Mission by the long stay-time trajectory aborts. on the martian surface. The second involves a short stay-time (<30 days on the martian •Common transit/surface habitat design. surface) mission. Table 1-1 characterizes •Maintenance of a robust, safe principal discriminators of the two scenarios. environment for crews throughout their In most studies, the short stay-time exploration. missions have only been invoked for the first •Substantial autonomy of crew and mission; to develop long stay-time capability system operations from ground control. would require close to total mission redesign and much higher cost for a continued 1.4 Testing Principal Assumptions program. and Choices The second alternative is to land each A number of assumptions and choices crew at a different location. This scenario were made in constructing this Reference would be permitted by the capability defined Mission. For each assumption, this section in the Reference Mission. The principal trade- provides a top-level trade analysis, the off is between the additional exploration that rationale for the choice, and guidance to might be accomplished by exploring three further research and development which distant sites versus the benefits of building up could strengthen, improve, or change the the capability to test settlement technologies choice. (such as closed life support systems) and the reduced risk provided by accumulating 1.4.1 Robust Surface Infrastructure surface assets at one site. As the range of The principal payoff from Mars exploration provided in the single location exploration lies in surface capability—stay- Mars outpost is high (hundreds of time, crew safety, exploration range, and kilometers), the advantages of exploring other factors that characterize the crew’s several landing sites were considered of lower performance environment. All dictate a priority for the Reference Mission. robust infrastructure. The choice to land all of the payloads and crews at the same site on 1.4.2 Split Mission Strategy four different opportunities was based on the The split mission strategy takes assumption that the marginal cost of advantage of the currently available additional surface capability would be a cost- capability to successfully fly and land effective way to substantially increase the automated spacecraft on another planet. Such accomplishment of the program. capability can be used to deliver supplies and

1-28 Table 1-1 Principal Discriminators of Short and Long Stay-Time Mission Scenarios

Long Stay-Times Short Stay-Times Key Discriminating Factor

Surface High Low Difference in time Accomplishment on surface Surface Low High Robust vs. limited risk/day surface capability Surface Low Low Difference of time risk/cumulative vs. robustness Interplanetary risk Low High

Available to Yes No direct launch Available to Yes Difficult split mission Abort to Mars Yes No surface Availability of Mars Yes No at every opportunity

equipment to support human missions increased number of transportation elements without a crew being present. By using this that must be used. capability to deliver cargo not absolutely The split mission strategy is contrasted necessary for transporting crews between with the “all-up” approach in which a single Earth and Mars, the size of the transportation vehicle, assembled in LEO, is capable of system (both launch vehicles and upper landing the required assets in a single mission stages) for any one mission becomes smaller to the surface. The principal trade-off is and thus less expensive to develop and between rendezvous and assembly in LEO manufacture. In addition, these cargo and rendezvous on the Mars surface. For the missions can be sent on the absolute all-up approach, significant capability is minimum energy trajectories between Earth required in LEO to assemble and fuel the and Mars because there is no time-critical or spacecraft. Previous designs (the 90-Day life support critical element on board. Study; see NASA, 1989) projected very high However, the total number of launches LEO infrastructure costs, which would have increases under this strategy which offsets at to be expended in the early phases of the least part of the cost savings due to the program. For chemically propelled spacecraft,

1-29 the logistics of transporting, storing, and propulsion was selected because of its higher loading propellants was excessive and propellant utilization efficiency and because inevitably high in cost. Because the best nuclear rockets were developed almost to departure orbit at Earth is different for each flight status in the 1960s. For any given Mars opportunity, the space-based velocity change needed to depart from or be infrastructure would have to be moved or captured at a planet, a nuclear thermal rocket reproduced, or additional propulsion uses approximately 50 percent less propellant penalties be taken to modify the vehicle’s than the theoretical best chemical engine. (The departure orbit for every launch to Mars. The Space Shuttle main engine is approaching this elimination of this element in the architecture theoretical upper limit.) The vast majority of provides a significant cost reduction. It has mass needed for a Mars mission is propellant, been assumed here that the capability of very and any option that reduces the need for precise landing on Mars can be developed propellant can lower the program life cycle technically, and that all assets for each flight cost by reducing the size and number of can be integrated on Earth and simply joined launch vehicles. Although such rockets might on Mars. These capabilities can be be expensive to test on Earth (the magnitude demonstrated on precursor robotic missions. of which has not been determined) with current environmental concerns, their use in While the savings resulting from a space should not present an environmental smaller transportation system may not alone issue for they are dangerous only after firing be sufficient to invoke the use of the split the engines for a significant period of time. mission strategy, the strategy does enhance Higher performance engines would be better, another assumed element of the Reference but typically require a large source of Mission—the use of in situ resource electrical power (from either a nuclear source utilization. By splitting the missions into or very large solar arrays) which calls for cargo and crew flights, infrastructure can be additional development to reach the same set up and operated before committing a crew level of maturity as nuclear thermal rockets. to a flight to Mars. Operating this infrastructure for an extended period prior to 1.4.4 In Situ Resource Utilization launching a crew also improves the confidence of using the Mars surface as a safe This technology (assumed to be currently haven for the crew. available) has been developed at breadboard level and can be demonstrated on robotic 1.4.3 Nuclear Thermal Propulsion missions. It provides significant benefits to the mission by reducing launch mass from High-performance propulsion is found to Earth and increasing robustness of surface be an enabling technology for a human systems where caches of consumables and exploration program. Nuclear thermal

1-30 surface vehicle fuels can be maintained. As planning. Study team members were not discussed in the previous section, any unanimous in the choice of a common habitat technology that can reduce the amount of for space transit, for landing on the surface, mass (and propellant is the largest single item and for surface habitation. Some argued that, on such a list) can do much to reduce life due to the different requirements, a common cycle cost. This is accomplished primarily by design was not in the best interest of the reducing the size and number of launches mission. This is an area for further research. from Earth and by providing a dual purpose infrastructure that not only provides 1.4.6 Nuclear Surface Power propellants for a return trip but also supports With no known natural resources on crew activities and helps reduce risk. Mars that can be used to generate power, a crew exploring Mars must rely on either 1.4.5 Common Habitat Design converting solar radiation or using a power A common habitat was chosen for the source they have brought with them. With Reference Mission primarily to save on cost Mars lying, on average, 50 percent farther over the life of the program. Because seven from the Sun as Earth, only 44 percent as separate habitats will be required to support much solar radiation reaches that planet. This the three crews sent to Mars, this item means a crew must bring 2.25 times as much becomes a likely candidate for a common solar energy collecting and converting approach rather than designing, testing, and systems to generate the same amount of building separate systems for the power as could be generated on Earth. Add to interplanetary leg, the surface leg, and the this a day-night cycle (which requires the transition between the two. It may not be addition of an energy charging and storage feasible to use a common design for all of the system) as well as martian dust storms (which components that make up a habitat. However, significantly diminish the amount of light some of the significant elements—such as the reaching the surface over extended periods of pressure vessel (both primary and secondary time) and the size of a solar power station on structure), electrical distribution, hatches, and Mars becomes both large in area and mass docking mechanisms—lend themselves to a and subject to interruption or diminished common approach. Inasmuch as these major effectiveness due to the dust storms. Of those elements of the habitat can be defined and sources of energy that can be brought with their cost estimated, a common design for the the crews, only a nuclear power source can habitats has been adopted for the Reference concentrate sufficient energy in a reasonable Mission. A significant amount of work still mass and volume. However, other concerns— remains on definition and design of interior environmental on Earth, operational on Mars, details of the habitats which will become part to name a few—are added to any mission that of future efforts associated with Mars mission considers the use of a nuclear power source.

1-31 Given these kinds of considerations, a to a small habitable space for an extended choice was made to rely primarily on nuclear duration can lead to cabin fever. Zero g has power for systems operating on the martian known debilitating effects on the human body surface. Power provided by the solar arrays that must be addressed. Radiation from a used during the transit to Mars will be constant background and the threat of solar available for backup and emergency flares require that protection be adequate for situations. However, the solar arrays will not background sources and that a safe haven be be sufficient to power the propellant provided for extreme events. All of these manufacturing plants that are also a key threats have engineering solutions that can feature of this mission architecture. make the extended stay in interplanetary space a viable prospect for the crew. But the 1.4.7 Abort to the Surface solutions typically require increases in size, Mars missions differ from Space Shuttle mass, and complexity of the vehicle and the and lunar missions in that once the crew is transportation elements that are used to move committed to launch, orbit mechanics force it from planet to planet. the crew to remain away from Earth for An alternate strategy, and one that was approximately 2 to 3 years. This imposes on selected for this Reference Mission, is to take all of the systems the need for a higher degree advantage of the martian surface as a safe of reliability and maintainability or for haven where open space, gravity, and multiple independent means of providing radiation protection are naturally available. life-critical functions (collectively referred to This strategy, referred to as “abort to the as robustness). surface,” builds on these naturally available There has been a tendency to view the resources and breaks from the previous martian surface as the most hostile location viewpoint of Mars as the most hostile for a crew during a Mars mission. However, environment encountered on the mission. The of the three environments that a crew will reliability and maintainability of the systems encounter—Earth, interplanetary space, and needed to keep the crew alive on the surface the martian surface—interplanetary space is no greater than that imposed on space- offers the highest potential for debilitating based systems. In fact, the buildup of an effects on the crew. Practicality dictates a infrastructure at a single site on the surface relatively small habitable space for the crew enhances the safe haven character of the during transit. To do otherwise causes a martian surface. This approach places a corresponding increase in the size and cost of greater burden on the entry, landing, and the systems, primarily launch vehicles and martian-based launch systems. However, the transfer stages, associated with the trade-off of making these systems a viable transportation system. But to confine the crew part of the abort strategy through increased

1-32 redundancy and reliability versus the 1.5 Conclusions and Recommendations enhancements needed to sustain a crew Based on both mission and programmatic through a 2- to 3-year interplanetary abort points of view, a number of conclusions and have tended to favor the abort to the surface recommendations are made in the following strategy. The enhancements that will be made areas: mission and systems, technology to various systems to allow an abort to the development, environmental protection, surface also work to the advantage of the program cost, international participation, and overall mission by improving the chances of program management and organization. the crews to successfully reach the surface and perform their exploration activities. 1.5.1 Mission and Systems

1.4.8 Design for the Most Difficult Conclusions Opportunity A feasible mission scenario and suite of The design of the Reference Mission was vehicles and other systems have been based on the premise that a series of closely integrated to meet the objectives initially set spaced missions would result in costs out for this study. In addition, the Reference significantly lower than the sum of an Mission addresses a long-standing issue equivalent number of single missions. To regarding extended-duration flights and crew achieve this cost savings requires that a single safety by adopting a view that the surface of set of systems be designed which can Mars is a safe haven and that equipment and accomplish the mission under the most procedures should be developed with this in difficult circumstances of any single mind. opportunity. The most significant of these The Reference Mission includes variations results from trajectory differences technology assumptions which require that occur during sequential mission further development and which contribute to opportunities. As a result, some systems may an estimated development cost that is higher have excess capability during some years. than can currently be supported. Both However, this allows the advantage of either technology and cost must be addressed and launching more payload mass in those years the alternative missions and systems could with more favorable trajectories or reducing result in a better program for human mission durations by flying shorter trajectory exploration of Mars. However, the mission legs, but at the expense of greater fuel and systems described here substantially consumption. For example, in the 2009 reduce the program cost and at the same time opportunity, transit times for piloted missions present a more robust approach than in are approximately 6 months; using the same previous studies of this subject. systems in the 2018 opportunity reduces transit times to just 4 months.

1-33 Recommendations the assumed technologies can be started now and, to a certain degree, may be required for •Use this study as an informal baseline such a program to progress. In the current against which future alternatives should political environment, investment in be compared. technology is seen as a means of improving •Continue investigating alternative the general quality of life for people on Earth, mission scenarios and systems to and multiple use of technologies is improve this Reference Mission, or emphasized to obtain the best return on the suggest a better alternative. resources invested in their development. The following is a list of twelve technologies 1.5.2 Technology Development which are important to space transportation, humans living in space or on a planetary Conclusions surface, or the utilization of extraterrestrial The Reference Mission was developed resources. assuming advances in certain technology Resource Utilization areas thought to be necessary to send people to Mars for a reasonable investment in time •Extraterrestrial mining techniques and resources. The Reference Mission is not •Resource extraction process and intended to lock in these assumed chemistry technologies. The purpose of identifying technologies at this time is to characterize •Material preparation and handling in those areas that can either significantly reduce reduced gravity the required mass or cost of the program or •Extraterrestrial manufacturing significantly reduce its risks (for example, in Transportation and Propulsion the area of fire safety). Alternative means of satisfying these requirements may be •Advanced chemical systems that provide identified and, if promising, should be high performance and are compatible supported. The alternatives could be the with the resources available on the Moon result of a dual use development, spin off and Mars from other programs, or a fortunate “spill •Nuclear propulsion to enable short trip over” from some unexpected area. times to Mars

At this particular stage in developing •Aerocapture/aerobraking at the Earth human exploration missions to Mars, it is and at Mars for propulsive efficiency difficult to do more than speculate about spin and reusable systems off and spill over technologies that could result from or be useful to this endeavor. •Lightweight/advanced structures However, identifying dual uses for some of • Reduced-g combustors

1-34 Cryogenic Fluid Management •Health care at remote locations

•Long-term (years) storage in space •Radiation protection in transit and on surface •Lightweight and high efficiency cryogenic liquefaction Power Generation and Storage

•Zero g and microgravity acquisition, •Long life, lighter weight, and less costly transfer, and gauging regenerative fuel cells

EVA Systems •Surface nuclear power of the order of 100kw •Lightweight, reserviceable, and maintainable suit and PLSS •High efficiency solar arrays

•Durable, lightweight, high mobility suits Teleoperations/Telerobotics and gloves •Remote operations with long time delays Regenerative Life Support Systems •Fine control manipulators to support •Contamination and particle control wide range of surface activities

•Loop closure •Telepresence sensors and displays

•Introduction of locally produced Planetary Rovers consumables •Long range (hundreds of km) rovers •Food production •Motor lubricants (long-term use) •Trash and waste collection and •Dust control processing •High efficiency lightweight power •High efficiency and lighter weight active generation and storage thermal control systems Advanced Operations Surface Habitation and Construction •Automated systems control •Lightweight structures •Systems management and scheduling •Seal materials and mechanisms •Simulations and training at remote •Construction techniques using local locations materials Fire Safety Human Health and Performance •Fire prevention •Zero-g adaptation and countermeasures •Fire detection •Human factors •Fire suppression

1-35 Some of these technologies (such as Recommendations nuclear thermal propulsion, Mars surface •Establish a Mars Program Office space suits, and in situ resource extraction), at (discussed further under International the system level, are unique to the Reference Participation and Management and Mission or to human space exploration in Organization) early in the process (now, general. It is likely that NASA or cooperating probably) at a low level to lay the international partners will have to bear the foundation for technology requirements burden for support of this research and to be undertaken by NASA or other development. The Reference Mission, as it is government agencies with similar described here, will fail if these systems are requirements. Formal organizational not advanced to a usable state. Other areas, agreements should exist between these such as medical countermeasures, closed-loop offices if the technology development is life support systems, autonomous operations not formally assigned to the Program systems, surface power systems, and surface Office. mobility, may be of more general interest and may provide opportunities for government •Rank technology investments according and industry to develop shared programs. In to their return to the Program, as either still other areas, such as long-lived electronics cost or risk reductions. and materials research, where the underlying •Prior to initiation of the Reference research will probably be done by industry to Mission, take critical technologies to a address general problems of technology demonstration stage. NASA should development, NASA or the international ensure that experimental work in partners should focus on infusing that support of the Reference Mission is technology. The exchange of information incorporated into the International Space should be continuous between NASA and the Station program at the earliest commercial sector particularly concerning the reasonable time. needs of future missions, so that industry can •Create a database (in the Program Office) incorporate research into its privately funded of available technologies that can be programs where it is justified. In all areas, used in design studies, and track the subsystem or component technologies may be progress of these technologies. The developed by industry to meet commercial database should include domestic and requirements, and the Mars Program will international capabilities. need to have processes that allow the element designers to use the most advanced capabilities available.

1-36 1.5.3 Environmental Protection extraterrestrial life. NASA itself has contributed to this perception by supporting Conclusions legitimate scientific research in this area. Fundamental principles of planetary Because it is not possible to prove that Mars is environmental protection have been completely devoid of life, there is the developed since the first planetary potential for misinterpretation or exploration missions began in the 1960s. With misunderstanding when martian materials respect to Mars, the principles adopted by the and human crews are brought back to Earth. international scientific community are For example, an ailment (regardless of the straightforward: Mars should be protected source) among a returning human crew could from biological contamination from Earth that give rise to speculation that the crew has would interfere with or confound the search some unknown Mars “bug” and is about to for natural martian organisms, and Earth expose the rest of the human population to its must be protected from contamination by effects. martian organisms harmful to the terrestrial biosphere. The United States is signatory to a Recommendations treaty under the auspices of the Committee on •Develop adequate and acceptable Space Research (COSPAR) which provides the human quarantine and sample handling basic framework for its Planetary Protection protocols early in a Mars exploration policy and program (COSPAR 1964 and program. The protocols must address United Nations 1967). not only the purely scientific concerns to Planetary protection will be an ongoing maintain the pristine nature of samples discussion at an international level. The but also the societal concerns, real or policy principles stated here and those that imagined, that are likely to arise. evolve in the future must be carried along as •Include the protocols as program-level significant requirements for mission planning requirements for mission and system and system design. development.

A further political concern is •Publicly release for review (by unfortunately tied to the planet Mars. A independent authoritative bodies) the significant portion of the popular press and principles and practices of the entertainment industry is devoted to contamination control in effect for Mars speculation about life, intelligent and missions. otherwise, that may exist beyond the planet Earth. Percival Lowell, H. G. Wells, Orsen Wells, and others have placed Mars in the forefront of possible locations for

1-37 1.5.4 Program Cost managing and running this type of program, estimating the cost for this phase of the Conclusions program was deferred until an approach is The cost of the Reference Mission was better defined. Similarly, the issue of estimated using standard models. Input for management reserve was not addressed until these models was derived from previous a better understanding of the management experience and information provided by approach and controls has been developed. members of the Study Team. Included in the When compared to earlier estimates of a estimate were the development and similar scale (NASA, 1989), the cost for the production costs for all of the systems needed Reference Mission is approximately an order to support three human crews as they explore of magnitude lower. A distribution of these Mars. In addition, ground rules and costs is shown in Figure 1-6. It can be seen assumptions were adopted that incorporated from this figure that the major cost drivers are some new management paradigms, as those associated with the transportation discussed later in the Program Management elements: the ETO launch vehicles, the TMI and Organization section. The management stages, and the Earth-return systems. costs captured program level management, integration, and a Level II function. Typical The Mars Study Team recognizes that, pre-production costs, such as Phase A and B even with the significant reduction in the studies, were also included. program cost achieved by this Team, the Reference Mission is probably still too Not included in the cost estimate were expensive in today’s fiscal environment. More selected hardware elements, operations, and work to further reduce these costs is needed. management reserve. Hardware costs not estimated include science equipment and EVA Recommendation systems, for which data were not available at •Seek alternative solutions or effective the time estimates were prepared; however, approaches to cost reduction in each of these are not expected to add significantly to the areas cited above. The efforts may the total. No robotic precursor missions are require revolutionary changes included in the cost estimate although their throughout NASA, the aerospace need is acknowledged as part of the overall industry, the United States, and the approach to the Reference Mission. world. Operations costs have historically been as high as 20 percent of the development cost. However, due to the extended operational period of the Reference Mission and the recognized need for new approaches to

1-38 1.5.5 International Participation Study (IAA 1993) describes in more detail the rationale and possible organizational Conclusions approaches to an international Mars The human exploration of Mars should exploration program. be inherently an international, indeed a The Reference Mission is rich in global, undertaking. Just as the U. S. landing possibilities for multinational or even global on the Moon excited and amazed the world at participation. Many major elements, systems, U. S. technological skills and organizational and subsystems will have to be developed accomplishment, the human exploration of and produced, precursor missions must be Mars can excite and amaze the people of the developed and flown, and operations world with a commonly sought level of capabilities must be developed; and the technological prowess and organizational mission operations can be designed to be capability. The International Academy of undertaken on an international basis. Three Astronautics’ International Mars Exploration types of international participants may

Phase A & B Cost of Surface Systems 2% Facilities Habitats 8% 8% Mgmt, Adv. Devel., 12% Program Support 12% Mars to Earth Vehicle 11%

Descent Vehicle 6% Earth to Orbit Vehicle Earth to Mars Vehicle 26% 18%

Figure 1-6 Distribution of Reference Mission costs.

1-39 contribute based on the ability to provide The ranges of opportunities and interests resources and participate technically in the are large and must be well understood before program. an international program is constructed. The discussions may be iterative with respect to •Countries with limited resources and initial design in order to optimize the technical base. Their participation could collective returns to all nations in the be linked to technology transfer to their program, and it is not unlikely that 10 years countries, which could improve the level would be needed to formulate the principles of technical education and take and agreements needed to undertake the advantage of technical internship in the program. It is important that these endeavor. These relationships might be discussions lead to a set of basic principles similar to the participation of Cuba or under which the program will be designed Viet Nam in the Russian space program. and implemented. •Countries with greater amounts of resources and technical base. Their Recommendations participation would reflect technical •Make the human exploration of Mars interest in limited areas targeted for program international from its inception, technical or industrial growth in their and take as a basic principle that all economies. The participation of Canada partners will have a voice in all phases of in the International Space Station the program in proportion to the program is an example. resources contributed to the program. •Countries with substantial resources and •Do not exclude any nation even though technical base. Their participation would their participation might be small in reflect a desire to demonstrate world economic terms. leadership, retain broad technological skills, and promote aerospace industry. •Create a forum in the near future for The major contributors to the discussion of the elements of an International Space Station program fall international program to lay the basis for into this category. international participation.

All participating countries should expect •Create an International Program Office to gain in proportion to their investment in (sensitive to political and technical the enterprise; richer countries might view issues) to lead the design effort. Just as it the program as an opportunity to help poorer is important to have all of the design countries improve their standards of living requirements understood prior to through stimulation and transfer of modern development, all of the political technology and technological training. requirements must also be understood early in the process.

1-40 1.5.6 Program Management and Space Station Freedom programs. To manage a Organization Mars exploration program to a lowest possible cost, several recommendations are proposed. Conclusions

Organization and management is one of Recommendations the principal determinants of program cost. •In subsequent studies of the Reference This is a rather wide-ranging topic, which is Mission, investigate the design of the not entirely divisible from the technical organization and management system. content of the program, because it includes •Reach a formal philosophical and budgetary program level decision-making that is agreement (between all parties) as to the intimately tied to the system engineering objectives and requirements imposed on the decision-making process. The relationship mission before development is initiated, and between program cost and program culture agree to fund the project to its completion. In (Figure 1-7) is an indication of that the U. S., this would include multiyear relationship. budgetary authority. This should be The relationship between cost and accompanied by a management process that management style and organizational culture would protect against program overruns is rather well-known in a general manner, through appropriate incentives. through a large number of “lessons learned” •Prepare a risk management plan. The human analyses made postprogram. The list of key exploration of Mars will have risks that are elements of lower-cost programs (shown in quite different from any space mission Table 1-2) have been pointed out in a series of previously undertaken. Two general types of analyses, but have not commonly been applied at the critical stage of developing program organization and management approaches. The organizational and Relative Cost Spacecraft management style has been determined rather late in the program, generally because the program content and final design was Aircraft typically delayed through redesign, changing Difficulty + requirements, and funding irregularities. For Trucks Ships + example, the International Space Station program went through several redesigns, and Specifications some of the hardware was actually in production when the program architecture was modified to integrate the Russian and Figure 1-7 Relationship between program cost and program culture.

1-41 risk seem to be most critical: risks to the •Establish a clear demarcation between safety of the crew and accomplishment the design phase and the development of the mission (primarily technical risks) and production phase of the project, and and risks of not meeting cost and do not allow development to begin schedule objectives. Maintaining launch before the design phase is ended. Prove schedule is important due to the all technologies prior to initiating dependency on several successful production of program elements. Do not launches for mission success and the change requirements after they are high cost of missed launch windows. established unless they can be relaxed. Failure to maintain the launch schedule Ensure that a system to document the implies a 2-year program delay at a relationship and interaction of all potentially high program cost. requirements exists and is available for

Table 1-2 Key Elements of Lower-Cost Programs

•Use government only to define requirements.

•Keep requirements fixed: once requirements are stated, only relax them; never add new ones.

•Place product responsibility in a competitive private sector.

•Specify end results (performance) of products, not how to achieve the results.

•Minimize government involvement (small program offices).

•Ensure that all technologies are proven prior to the end of competition.

•Use the private sector reporting system: reduce or eliminate specific government reports.

•Don’t start a program until cost estimates and budget availability match.

•Minimize or eliminate government-imposed changes.

•Reduce development time: any program development can be accomplished in 3 to 4 years once uncertainties are resolved.

•Force people off of development programs when development is complete.

•Incentivize the contractor to keep costs low (as opposed to CPAF, CPFF of NASA).

•Use geographic proximity of contractor organizations when possible.

•Use the major prime contractor as the integrating contrator.

1-42 use prior to the beginning of production. multinational activity). The Program The Reference Mission requires a Office will be in place to manage number of elements, many of which are technical requirements, provide technically alike but serve somewhat decisions that require consultation and different functions over the duration of trade-offs (both technical and political), the program. For example, the surface and manage development contracts. The habitat may be the basis for the transit Program Office should establish habitat; each of the habitats delivered to functional requirements for the design the surface will have a different phase and conduct a competitive complement of equipment and supplies, procurement for the design phase, with according to its position in the delivery the selection of a prime contractor. sequence. The elements will be •Prepare a specific construction sequence developed over a period of several years, and plan to accompany each production and there will be a temptation to element of the program. Once improve the equipment and supply committed to development, the manifest. To maintain cost control for the development time should be strictly program, requirements must be fixed at limited if costs are to be contained. This the time of initial development. will be difficult in the Mars program, •Provide clear requirements for the where it probably will be effective to design phase, describing the produce common elements sequentially performance expected and a clear set of rather than all at one time, although criteria for completeness of design as a there may be a high enough production function of resources expended in rate that costs will drop as experience is design. Use a significant design cost gained. A new approach will be needed margin to manage the design resources. to ensure that the development time for Terminate the project if a satisfactory each individual element is strictly design cannot be accomplished within limited. the available resources. Further, select •Make the two levels of integration, the successful prime contractor as program and launch package, the integration contractor for the responsibility of a single organization—a development phase, and exclude the prime contractor to the Program Office. prime contractor as a development The program will require two levels of contractor. The design phase of the integration, similar to that of the program is critical to successful cost International Space Station program: a control, and should be based on a set of program level which ensures that overall functional requirements established by mission requirements are met at each the Program Office (which may well be a

1-43 stage of the mission, that is, for the 1.6 References packages assembled for each launch Borowski, S. K., R. R. Corban, M. L. opportunity; and a launch package level McGuire, and E. G. Beke, “Nuclear integration, in which all required Thermal Rocket/Vehicle Design Options elements of each launch to Mars are for Future NASA Missions to the Moon packaged and their performance and Mars,” NASA Technical ensured. Memorandum 107071, 1993. •Include operational considerations in the Committee on Space Research (COSPAR), design and development phases of the “Statement on the Potentially Harmful program, and use life cycle costs for Effects of Space Experiments Concerning program design and development the Contamination of Planets,” COSPAR decisions. The operational phase of the Information Bulletin No. 20, pp. 25-26, Mars program must be represented in Geneva, Switzerland, 1964. the design and development phase. This will require a concurrent engineering Duke, M. and N. Budden, “Results, approach which considers the Proceedings and Analysis of the Mars operational costs as well as the Exploration Workshop,” JSC-26001, development costs in a life cycle cost NASA, Johnson Space Center, Houston, approach to the program. If the Texas, August 1992. approaches identified above to separate International Academy of Astronautics design and development and to obtain (IAA), “International Exploration of Mars: prior commitments for funding for the A Mission Whose Time Has Come,” Acta entire program are successful, there Astronautica, Vol. 31, pp. 1-101, New York, should be less of a problem maintaining USA, October 1993. the life cycle cost approach to United Nations, “Treaty on Principles minimizing program costs. Governing the Activities of States in the •Put into place positive incentives to Exploration and Use of Outer Space, maintain program costs within approved Including the Moon and Other Celestial levels at all stages of design, Bodies,” U.N Document A/RES/2222/ development, production, and (XXI), TIAS #6347, New York, USA, operations, and to reduce costs of each January 1967. phase of the program. NASA, "Report of the 90-Day Study on Human Exploration of the Moon and Mars," NASA Headquarters, Washington, DC, November 1989.

1-44 Synthesis Group, “America at the Threshold: Report of the Synthesis Group on America’s Space Exploration Initiative,” U.S. Government Printing Office, Washington DC, May 1991.

Zubrin, Robert, “Mars Direct: A Simple, Robust, and Cost Effective Architecture for the Space Exploration Initiative,”29th Aerospace Sciences Meeting, AIAA 91- 0326, held in Reno, Nevada, January 7-10, 1991.

1-45 2. Science and Exploration Rationale

2-1 2-2 2.1 Introduction autonomous manner with only general support from Earth. From the rationale Mars is an intriguing and exciting planet generated by the Mars Study Team for with many adventures and discoveries sending human crews to Mars, goals and awaiting planetary explorers. But before we objectives are derived to provide guidance for go, we must provide the tools the explorers the exploration crews during their extended will use, anticipate as much as possible the stay on the martian surface. This section will situations they will encounter, and prepare discuss that Study Team rationale. them for the unexpected. For the first time in a space exploration mission, it will be up to 2.2 The “Why Mars” Workshop the crew and supporting personnel on Earth to create specific activities as the mission In August 1992, a workshop was held at progresses and discoveries are made. The the Lunar and Planetary Institute in Houston, length of time spent on the martian surface, as Texas, to address the “whys” of Mars presented in the Reference Mission, will exploration. This workshop brought together preclude development of the detailed, highly a group of experts (listed in Table 2-1) familiar choreographed mission plans typical of with the key issues and past efforts associated today’s space missions. The crew will have with piloted Mars missions in an effort to general goals and objectives to meet within provide the top-level rationale and their other time constraints (for example, requirements from which the Mars exercise for health maintenance, regular exploration program could be built (Duke medical checks, routine systems maintenance, and Budden, 1992). This group was asked to etc.). Based on knowledge gained from generate three key products: a Mars mission precursor robotic missions, the crew will land rationale, Mars exploration objectives, and a in an area that has a high probability of list of key issues and constraints, to be used satisfying the pre-set mission objectives. by the Mars Study Team (members listed in However, due to the extended Table 2-2) to define the technical details of a communications time lag between Earth and Reference Mission. The workshop attendees Mars, the crews and their systems must be identified six major elements of the rationale able to accomplish objectives in a highly for a Mars exploration program.

2-3 Table 2-1 Mars Exploration Consultant Team

Dr. David Black Dr. George Morgenthaler Director University of Colorado Lunar and Planetary Institute Boulder, Colorado Houston, Texas Dr. Robert Moser Dr. Michael Carr Chama, New Mexico U.S. Geological Survey Menlo Park, California Dr. Bruce Murray California Institute of Technology Dr. Ron Greeley Pasadena, California Dept. of Geology Arizona State University Mr. John Niehoff Tempe, Arizona Science Applications International Corporation Dr. Noel Hinners Schaumburg, Illinois Lockheed Martin Denver, Colorado Dr. Carl Sagan Center for Radiophysics and Space Dr. Joseph Kerwin Research Skylab Astronaut Cornell University Lockheed Martin Ithica, New York Houston, Texas Dr. Harrison Schmitt Mr. Gentry Lee Apollo 17 Astronaut Frisco, Texas Albuquerque, New Mexico

Dr. Roger Malina Dr. Steven Squyers Center for EUV Astrophysics Cornell University University of California Ithica, New York Berkeley, California Mr. Gordon Woodcock Dr. Christopher McKay Boeing Defense and Space Group NASA Ames Research Center Huntsville, Alabama Moffett Field, California

2-4 Table 2-2 Mars Study Team

Dr. Geoff Briggs Mr. Kent Joosten NASA Ames Research Center NASA Johnson Space Center Moffett Field, California Houston, Texas

Ms. Jeri Brown Mr. David Kaplan NASA Johnson Space Center NASA Johnson Space Center Houston, Texas Houston, Texas

Ms. Nancy Ann Budden Dr. Paul Keaton NASA Johnson Space Center Los Alamos National Laboratory Houston, Texas Los Alamos, New Mexico

Ms. Beth Caplan Mr. Darrell Kendrick NASA Johnson Space Center NASA Johnson Space Center Houston, Texas Houston, Texas

Mr. John Connolly Ms. Barbara Pearson NASA Johnson Space Center NASA Johnson Space Center Houston, Texas Houston, Texas

Dr. Michael Duke Mr. Barney Roberts NASA Johnson Space Center NASA Johnson Space Center Houston, Texas Houston, Texas

Dr. Steve Hawley Mr. Ed Svrcek NASA Johnson Space Center NASA Johnson Space Center Houston, Texas Houston, Texas

Mr. William Huber Mr. David Weaver NASA Marshall Space Flight Center NASA Johnson Space Center Huntsville, Alabama Houston, Texas

•Human Evolution – Mars is the most permanent human presence beyond accessible planetary body beyond the Earth. However, it is not an objective of Earth-Moon system where sustained the Reference Mission to settle Mars but human presence is believed to be to establish the feasibility of, and the possible. The technical objectives of Mars technological basis for, human exploration should be to understand settlement of that planet. what would be required to sustain a

2-5 •Comparative Planetology – The scientific The workshop attendees then translated objectives of Mars exploration should be these elements into two specific mission to understand the planet and its history objectives. For the first human exploration of to better understand Earth. Mars:

•International Cooperation – The political •A better understanding is needed of environment at the end of the Cold War Mars—the planet, its history, and its may be conducive to a concerted current state. And to answer, as best as international effort that is appropriate, possible, the scientific questions that and may be required, for a sustained exist at the time of the exploration, a program. better understanding of the evolution of •Technology Advancement – The human Mars’ climate and the search for past life are pressing issues. exploration of Mars currently lies at the ragged edge of achievability. Some of the •It is important to demonstrate that Mars technology required to achieve this is a suitable location for longer term mission is either available or on the human exploration and settlement. horizon. Other technologies will be The following sections discuss the details pulled into being by the needs of this of the science and exploration rationale as mission. The new technologies or the applied to the Reference Mission. new uses of existing technologies will Implementation details are in Section 3. not only benefit humans exploring Mars but will also enhance the lives of people 2.3 Science Rationale on Earth. Mars is an intriguing planet in part for •Inspiration – The goals of Mars what it can tell us about the origin and history exploration are bold, are grand, and of planets and of life. Visible to the ancients stretch the imagination. Such goals will and distinctly reddish in the night sky, it has challenge the collective skill of the always been an attractive subject for populace mobilized to accomplish this imaginative science fiction. As the capability feat, will motivate our youth, will drive for space exploration grew in the 1960s, it technical education goals, and will excite became clear that, unlike Earth, Mars is not a the people and nations of the world. planet teeming with life and has a harsh •Investment – In comparison with other environment. The images of Mariner 4 classes of societal expenditures, the cost showed a Moon-like terrain dominated by of a Mars exploration program is large impact craters (Figure 2-1). modest.

2-6 Figure 2-1 Orbital image of Mars.

2-7 This terrain now is believed to represent exhibits later volcanic and tectonic features. ancient crust, similar to the Moon’s, formed in Large volcanoes of relatively recent activity an initial period of planetary differentiation. (Figure 2-2) and large crustal rifts due to Mariner 9 showed for the first time that Mars tensional forces (Figure 2-3) demonstrate the was not totally Moon-like, but actually working of internal forces.

Figure 2-2 Olympus Mons, the largest volcano in the solar system.

2-8 Figure 2-3 Across the middle is Valles Marineris, a huge canyon as long as the United States.

2-9 The absolute time scale is not accurately •What are the implications of such calibrated; however, by analogy with the changes for environmental changes on Moon, the initial crustal formation may have Earth? occurred between 4 billion and 4.5 billion •Were the conditions on early Mars years ago, and the apparent freshness of the enough like those of early Earth to guide large martian volcanoes suggests their a search for past life? formation within the last billion years. These questions are part of the Mars Many scientific questions exist regarding scientific exploration addressed by the Mars and its history and will continue to exist Reference Mission, and these questions can be long after the first human missions to the answered only by understanding the planet have been achieved. Two key areas of geological attributes of the planet: the types of scientific interest are the evolution of martian rocks present, the absolute and relative ages climate and the possible existence of past life. of the rocks, the distribution of subsurface Mars’ atmosphere now consists largely of water, the history of volcanic activity, the carbon dioxide with a typical surface pressure distribution of life-forming elements and of about 0.01 of Earth’s atmosphere compounds, and other geologic features. (comparable to Earth’s atmospheric pressure These attributes all have to be understood in at an altitude of approximately 30,000 meters the context of what we know about the Earth, or 100,000 feet) and surface temperatures that the Moon, and other bodies of our solar may reach 25°C (77°F) at the equator in system. midsummer, but are generally much colder. Addressing the question of whether life At these pressures and temperatures, water ever arose on Mars can provide a cannot exist in liquid form on the surface. fundamental framework for an exploration However, Mariner 9 and the subsequent strategy because, in principle, the search for Viking missions observed features which past life includes investigating the geological indicate that liquid water has been present on and atmospheric evolution of the planet. It is Mars in past epochs (Figure 2-4). generally understood that the search for Evidence for the past existence of evidence of past life cannot be conducted running water and standing water has been simply by a hit-and-miss landing-and-looking noted, and the interpretation is that the strategy, but must be undertaken in a step- atmosphere of Mars was thicker and wise manner in which geological provenances warmer—perhaps much like Earth’s early that might be suitable are characterized, atmosphere before the appearance of oxygen. located, and studied (Exobiology Program Three questions arise: Office, 1995). The characteristics of suitable exploration sites are highly correlated with •What was the reason for the change of the search for past or present water on the atmospheric conditions on Mars?

2-10 Figure 2-4 Dense tributary networks indicative of past presence of liquid water on Mars.

2-11 planet. Within the geological framework, aqueous fluids, as found in the SNC strategic questions related to the search for meteorites) is of major interest. Can the evidence of life can be posed. channels apparently formed by water erosion be demonstrated to have •What is the absolute time scale for experienced running water? Is there development of the major features on verifiable evidence for the existence of Mars? This would include determining ponds of water? What is the distribution the time of formation of the martian of subsurface permafrost, and can the crust, a range of formation ages for features interpreted as permafrost volcanic plains, and the age of the collapse be verified? youngest volcanoes. With this information as a guide, the age of •What are the distribution and formation of water-formed channels characteristics of carbon and nitrogen— should be boundable, and the the organogenic elements? Where do organogenic element content of martian they exist in reduced form? In what materials as a function of time may be environments are they preserved in their obtainable. As is inferred from the SNC original state? Is there chemical, isotopic meteorites which are believed to have (hydrogen, carbon, nitrogen isotopes), or originated on Mars (Bogard, et al., 1983 morphological evidence that will link and McSween, 1994), impacts on Mars concentrations of organogenic elements have preserved samples of the martian to the past existence of life? atmosphere in shock-produced glasses. •If organic remains can be found, how Thus, it may be possible to characterize extensive are they in space and time? the evolution of the atmosphere from What are their characteristics, variety carefully selected samples of impact and complexity? How are they similar or glass. different to biological materials on •What is the evidence for the distribution Earth? in space and time of water on the Answers to these questions may be surface? This would include water sought through orbital mapping (for example, combined in widely distributed igneous to determine the distribution of hydrothermal or clay minerals, in localized deposits mineral deposits), in situ studies (surface such as hydrothermal vents, in mineralogy, distribution of volatile elements), subsurface permafrost, in the polar caps, sample return (age of rock units, detailed and in the atmosphere. The distribution, chemistry, mineralogy, and isotopic age, composition, and mode of composition), and human exploration with formation (minerals formed by reaction sample return (similar but with more highly with or deposition from heated or cool intelligent sample collection). The scientific

2-12 community debates the precise order of modes of exploration that cannot be achieved investigative means used to achieve this robotically, then the human mission will be strategy, but generally concludes that the cost effective on scientific grounds. question of distribution of past life will be of such a difficult nature that sample return will 2.4 Exploration Rationale be required and that humans will ultimately Aside from purely scientific benefits, the choose to carry out the exploration in person. human exploration of Mars brings with it Given the assumption that humans will many tangible and intangible near-term take on the bulk of this type of exploration, benefits such as: the key questions become: •New associations between groups or •What is the appropriate role and place in disciplines which previously have not the exploration strategy of robotic interacted, but because of common sample return missions? objectives in exploration find new strengths and opportunities (for •Scientifically, where is the appropriate example, new international cooperation). transition from robotic missions, conducted routinely, and human •New technologies which may be used exploration missions, which may be for practical application on Earth or in singular, large, and not reproducible? other space enterprises (dual-use technologies). General guidelines are needed to answer these questions. Sample return missions •Education of a new generation of should be favored when they can be used to engineers and scientists spurred by the significantly reduce the number of dream of Mars exploration. subsequent missions to address the geological In the long term, the biggest benefit of modeling of the planet. Sample return the human exploration of Mars may well be missions are likely to be more expensive than the philosophical and practical implications one-way missions, so to be cost effective, they of settling another planet. must reduce the need for a proportionally larger number of subsequent missions or 2.4.1 Inhabiting Another Planet garner otherwise unobtainable information if their justification is purely scientific. From a The dream of human exploration of Mars scientific perspective, the guidelines for is intimately tied to the belief that new lands human exploration are similar. If a human create new opportunities and prosperity. In exploration mission promises to answer the human history, migrations of people have major strategic questions better than a larger been stimulated by overcrowding, exhaustion number of robotic explorers, or opens new of resources, the search for religious or

2-13 economic freedom, competitive advantage, The fact that, once on Mars, humans cannot and other human concerns. Rarely have easily return to the Earth (and then only at humans entered new territory and then specified times approximately 26 months completely abandoned it. A few people have apart) makes it necessary to develop systems always been adventurous enough to adopt a with high reliability and robustness. newly found territory as their home. Most of At the present level of human the settlements have eventually become technological capability, a self-sufficient economically self-sufficient and have settlement on Mars stretches our technical enlarged the genetic and economic diversity limits and is not economically justifiable, but of humanity. The technological revolution of it is imaginable. If, however, transportation the twentieth century, with high speed costs were to be reduced by two orders of communication and transportation and magnitude, such settlements might become integrated economic activity, may have economically feasible. What kind of strategy reversed the trend toward human diversity; should be followed to explore the concept of however, settlement of the planets can once humans permanently inhabiting Mars? Three again enlarge the sphere of human action and considerations are important. life. •Demonstrating the potential for self- Outside the area of fundamental science, sufficiency. This would include the possibility that Mars might someday be a understanding the potential to obtain all home for humans is at the core of much of the important materials to support human popular interest in Mars exploration. A habitation from the natural materials of human settlement on Mars, which would Mars. It is most important that humans have to be self-sufficient to be sustainable, be able to capture energy for driving would satisfy human urges to challenge the processes and have access to natural limits of human capability, create the resources (such as water, oxygen, potential for saving human civilization from agricultural raw materials, building an ecological disaster on Earth (for example, a materials, and industrial materials) from giant asteroid impact or a nuclear incident), martian rocks and soil. Demonstrating and potentially lead to a new range of human self-sufficiency requires that resources be endeavors that are not attainable on Earth. located and technology and experience The settlement of Mars presents new be developed to efficiently extract them problems and challenges. The absence of a from the in situ materials. Much can be natural environment that humans and most done robotically to locate resources prior terrestrial fauna and flora would find livable to arrival of the first human crew. and the current high cost of transportation are Extraction technology depends on a the main barriers to human expansion there. more detailed understanding of the

2-14 specific materials present on Mars and International Space Station program to requires the detailed mineralogical and be conducted in the late 1990s. Some of chemical analyses generally associated these concerns can also be addressed on with sample return missions. An the first human exploration missions to exception is the production of water, Mars, in which greater risks may be methane, and oxygen from the martian taken than are appropriate for later atmosphere, which is now known well settlement. enough to design extraction technology •Demonstrating that the risks to survival (Sullivan, et al., 1995). In addition to the faced in the daily life of settlers on Mars extraction and use of martian resources, are compatible with the benefits self-sufficiency undoubtedly requires perceived by the settlers. Risks to highly advanced life support systems in survival can be quantified through the which most of the waste product from Mars exploration program. However, the human activity is recovered and reused, benefits will be those perceived by and food is grown on the planet. future generations and cannot be •Demonstrating that human beings can addressed here. survive and flourish on Mars. This will likely be first explored by long-duration 2.4.2 International Cooperation missions in Earth orbit and may be The space age gained its start in a period continued in the 1/6-g environment of of intense technical and social competition the Moon (Synthesis Group, 1991). Two between East and West, represented by the types of needs—physical and Soviet Union and the United States. psychological—must be met for humans Competition during the International to survive and flourish on Mars. Physical Geophysical Year resulted in the Soviet Union needs will be met through advanced life being the first to launch a satellite into Earth support systems, preventive medical orbit, which served to challenge and remind sciences (nutrition, exercise, the United States that technological environmental control, etc.), and the supremacy was not solely the province of the capability of medical support for people United States. on Mars. Psychological needs will be met through the design of systems, The start of the Apollo program was a identification and selection of work for political decision based more on the crews, communications with Earth, and perception of the political and technological a better understanding of human rewards to be gained by attacking a truly interactions in small communities. Many difficult objective in a constrained time of these can be addressed through a period. The space race began, the United lunar outpost program or in the States won it, and a relatively few years later,

2-15 the Soviet Union collapsed. Fortunately, the Section 3 of this report will illustrate that Russians did not view Apollo success as a much of the technology needed for a Mars reason to terminate their space exploration mission is either currently available or within program, and they continued to develop the experience base of the spacefaring nations capabilities that are in many areas on a par of the Earth. No fundamental breakthroughs with United States capabilities. Also, during are required to accomplish the mission. the post-Apollo time frame, space capability However, an extended period of advanced grew in Europe (with the formation of the development will be required to prepare the European Space Agency), Japan, Canada, systems needed to travel to and from Mars or China, and other countries. With these to operate on the surface of Mars; specifically, developments, the basis has been laid for a high efficiency propulsion systems, life truly international approach to Mars support systems, and an advanced degree of exploration—an objective in which all automation to operate, and if necessary humanity can share. repair, processing equipment. At a general level, perhaps two of the most important The exploration of Mars will derive ways in which the Reference Mission will significant nontechnical benefits from help advance technology that will benefit structuring this undertaking as an more than just this program is to provide the international enterprise. It is unnecessary for programmatic “pull” to bring technologies to any country to undertake human exploration a usable state and the “drive” to make of Mars alone, particularly when others, who systems smaller, lighter, and more efficient for may not now have the required magnitude of a reasonable cost. capability or financial resources, do have the technological know-how. An underlying For any of the technology areas requirement for the Reference Mission is that mentioned above (as well as others not it be implemented by a multinational group mentioned), this program will require of nations and explorers. This would allow systems using these technologies to meet for a continuation of the cooperative effort performance specifications and be delivered that is being made to develop, launch, and on schedule, all at a pace perhaps not operate the International Space Station. otherwise required. This applies to any development effort. But for the Reference 2.4.3 Technological Advancement Mission, many technologies will need to be From the outset, the Reference Mission ready at once, causing many of these systems was not envisioned to be a technology to advance in maturity much faster than development program. The Mars Study Team might have otherwise been possible. These made a deliberate effort to use either mature systems and related technologies will technology concepts that are in use today or then be available to the marketplace to be basic concepts that are well understood.

2-16 used in applications limited only by the necessary to be used on the Reference imagination of entrepreneurs. Mission. Once developed, these technologies become available for use, perhaps on reusable The matured systems and the vehicles, for the ever-increasing traffic in LEO technologies behind them will be attractive up to geosynchronous altitude. to entrepreneurs in part because of the effort to make them smaller, lighter, and more Another area of tremendous leverage for efficient. A kilogram of mass saved in any of a mission to other planets is the ability to use these systems saves many tens of kilograms resources already there rather than burdening of mass at launch from Earth (depending on the transportation system by bringing them the propulsion system used) simply because from Earth. Focusing on understanding what less propellant is required to move the is required for eventual settlement on Mars systems from Earth to Mars. Smaller, lighter, leads quickly to those technologies that allow or more efficient each translate into a the crew to live off the land. Of the known competitive advantage in the marketplace raw materials available on Mars, the for those who use these technologies. atmosphere can be found everywhere and can be used as feedstock to produce propellants Among the specific areas of desirable and life support resources. Other raw technology advancement is propulsion materials (such as water) will eventually be systems. Even the earliest studies for sending found and used, but sufficient detail is not people to the Moon or Mars recognized that currently known about their locations and propulsion system efficiency improvements quantities. This is an objective for initial have tremendous leverage in reducing the exploration. size of the complete transportation system needed to move people and supplies. Much of the processing technology Chemical propulsion systems are reaching needed to produce propellants from the theoretical limits of efficiency in the atmospheric gases already exists and is in use rocket engines now being produced. Further on Earth. However, integrating these improvements in efficiency will require the technologies into a production plant that can use of nuclear or electrical propulsion operate unattended for a period of years, concepts which have the potential of including self-repair, is an area where improving propulsion efficiencies by a factor additional development effort will be of up to 10, with corresponding reductions in required. (Chemical processing plants on the amount of propellant needed to move Earth are making significant progress toward payload from one place to another. Both of autonomous operation even now.) In this these propulsion technologies have matured area, the Reference Mission will adapt the to a relatively high state of readiness in the existing technologies at the time of the past, but neither has reached the level Reference Mission rather than pull those

2-17 technologies up to the levels needed by the Reference Mission possible. Equal with this is program. Regardless of how this technology instilling an attitude of cost consciousness in is developed, the advantages in the engineering community that will design manufacturing and materials processing will and produce these systems. The importance be significant. of cost as a design consideration and providing the tools to accurately forecast cost Life support systems is another specific should be incorporated in the educational area where advancing the state of the art can system that trains these engineers. significantly reduce the overall size of the systems launched from Earth. The same 2.4.4 Inspiration technologies that produce propellants can also produce water and breathable gases for It can be argued that one role of human crews. These resources can be used as government is to serve as a focusing agent for makeup for losses in a closed or partially those events in history that motivate and closed life support system, and can also serve unify groups of people to achieve a common as an emergency cache should primary life purpose. Reacting to conflicts quickly comes support weaken or fail. Life support for this to mind as an example. For the United States, Reference Mission can take advantage of World War II and the Persian Gulf War are developments already made for International examples of how a nation was unified in a Space Station and submarine use. positive sense; the Viet Nam War is an Developments in support of the Reference example of how the opposite occurred. Mission are likely to return technologies that It can also be argued that a role of are smaller, more efficient, and perhaps less government is to undertake technical and costly than those available at the time. engineering projects that can inspire and Important in all of these areas is a focus challenge. The great dam building projects in on ensuring that the cost to manufacture and the American West during the 1930s is an operate these systems is affordable in the example of the government marshaling the current economic environment. The design- resources to harness vast river systems for to-cost concept is not currently well electrical power and irrigation to allow for understood in the aerospace industry, and population growth. The Interstate Highway any advancements in this area will benefit System is another example that receives little development programs well beyond those fanfare but has changed the way we live. The connected with the Reference Mission. government incentives to private entities that Developing the tools needed to determine led to the development of the vast costs that are as easy to use as the tools used intercontinental rail system in the last century to predict system performance is one of the is another example. key technology areas that will help make the

2-18 Few government efforts can collectively the infrastructure that affects our everyday motivate, unify, challenge, and inspire. The life: the use of space for business, commerce, Apollo program was one such example that and entertainment. Just as space projects do focused a national need to compete with now, the Reference Mission can serve as a another nation in a very visible and high focal point for invigorating the scientific, profile manner; the Reference Mission can technical, and social elements of the serve as another. In this instance, the education system, but with a much longer undertaking provides a focus for the human range vision. need to struggle and compete to achieve a worthy goal—not by competing against each 2.5 Why Not Mars? other but rather against the challenges Several impediments may severely presented by a common goal. hamper the implementation of a program for the human exploration of Mars. Some 2.4.5 Investment impediments are due simply to the fact that Scientific investigation, human they have not been evaluated in sufficient expansion, technology advancement, and detail to gauge their impact. Others are inspiration are not attainable free of charge. simply beyond the control of this or any other Resources must be devoted to such a project program and must be taken into account as for it to succeed; and at a certain level, this the program advances. The following can be viewed as denying those resources to paragraphs discuss some of these other worthy goals. The Reference Mission impediments as viewed by the Mars Study costs are high by current space program Team and others considering programs of this standards, and additional effort is needed to type (Mendell, 1991). reduce these costs. The total program and annual costs of the Reference Mission range 2.5.1 Human Performance from 1 percent to 2 percent of the current It is a known fact that the human body Federal budget—still far below other Federal undergoes certain changes when exposed to programs. If this program expands to an extended periods of weightlessness—changes international undertaking, the costs incurred that are most debilitating when the space by each partner would be reduced even more. traveler must readapt to gravity. The most A debate must still occur to determine if serious known changes include this project is a worthwhile investment of the cardiovascular deconditioning, decreased public’s resources. But the use of these muscle tone, loss of calcium from bone mass, resources should be viewed as more than just and suppression of the immune system. A an effort to send a few people to Mars. This variety of countermeasures for these project will be investing in a growing part of conditions have been suggested, but none

2-19 have been validated through testing for long- time required for recovery is particularly term, zero-g spaceflight. The Russians have important if the surface stay is short (as has had some success with long periods of daily been proposed for “opposition-class” exercise to maintain cardiovascular capacity missions). and muscle tone, but monotonous and time- No one knows whether exposure to a consuming exercise regimes affect the gravity field lower than the Earth’s will efficiency and morale of the crew. reverse the deconditioning induced by Artificial gravity is often put forward as a weightless space travel. And if some level of possible solution. In this case, the entire gravity does halt the deconditioning effects, spacecraft, or at least that portion containing what level is too low? In other words, if a the living quarters for the crew, would be crew arrives on Mars in good physical rotated so that the crew experiences a condition, what will their condition be after constant downward acceleration that spending an extended period of time under simulates gravity. It is generally assumed that martian gravity? Artificial gravity cannot be the Coriolis effect (the dizziness caused by provided easily on the martian surface, and spinning around in circles) will fall below the Apollo missions to the Moon were too short threshold of human perception if the to produce observable differences between spacecraft is rotated at a slow rate. It is not the condition of the astronauts who went to known whether simulation of full terrestrial the surface and those who remained gravity is required to counteract all of the weightless in orbit. known deconditioning effects of The human body’s reaction to Mars weightlessness, or whether the small residual surface conditions, other than gravity, is also Coriolis effect will cause some disorientation not yet known. The Viking missions to Mars in crew members. No data from a space-based found a highly reactive agent in the martian facility exists, and the space life science soil, an explanation for which has not yet research community is split over the viability been agreed to by the scientific community. of artificial gravity as a solution. Without understanding this agent’s chemical Deconditioning is a critical issue for Mars behavior, its impact on human crews cannot missions because the crew will undergo high be determined. No matter how carefully the transient accelerations during descent to the Mars surface systems are designed and no martian surface. Depending on the matter how carefully the crews handle native physiological condition of the crew, these materials, small amounts of the martian accelerations could be life threatening. Once atmosphere and soil will be introduced into on the surface of Mars, the crew must recover crew living compartments during the course without external medical support and must of the mission. It will be necessary to better perform a series of demanding tasks. The characterize the Mars environment and assess

2-20 its impact on the crew. Assuring the health be no opportunity for resupply. Either the and safety of the crew will be of obvious systems must work without failure or the importance. crew must have adequate time and capability to repair those elements which fail. Psychiatrists and psychologists agree that piloted missions to Mars may well give rise to Particularly important to the success of behavioral aberrations among the crew as piloted Mars missions will be testing of have been seen on Earth in conditions of integrated flight systems under conditions stress and isolation over long periods of time. similar to the actual mission for periods of The probability of occurrence and the level of time similar to, and preferably much greater any such anomalous behavior will depend than, the actual mission. Integrated flight not only on the crew members individually testing is truly critical if the flight system is but also on the group dynamics among the the first of its kind. Unfortunately, if history is crew and between the crew and mission a guide, budget pressures will cause program support personnel on Earth. In general, the management to search for substitutions for probability of behavior extreme enough to full-up flight testing. (For full-up flight threaten the mission will decrease with an testing, hardware identical to that used in increased crew size. However, the expense of flight is operated for periods of time equal to sending large payloads to Mars to support a or greater than the actual mission which large crew will limit the number of people in allows weaknesses or failures to be identified any one crew. At the present time, little effort and corrected. This is the most expensive way has been spent developing techniques for to test, in terms of time and money.) After all, crew selection that will adequately guarantee most of the expense of a mission to Mars is in psychological stability on a voyage to Mars launch and operations, two categories of and back. Russian experience suggests that a expense for a flight test whose magnitude crew should train together for many years would be similar to that of an actual mission. prior to an extended flight. And what possible motivation would there be for a crew to spend 2 or 3 years in orbit 2.5.2 System Reliability and Lifetime pretending to go to Mars?

The spacecraft and surface elements will Somewhere in a large, complex program, likely be the most complex systems a manager will take a shortcut under pressure constructed up to that point in time, and the from budget or schedule reasons, and the lives of the crew will depend on the reliability consequences will not always be obvious to of those systems for at least 3 years. By program management. As a result, the comparison, a Mars mission will be of a reliability of the product will be duration at least two orders of magnitude overestimated. And management always greater than a Shuttle mission, and there will expresses a very human tendency to believe

2-21 good news. (This can be illustrated by the Shortening development time can be change in the official estimates of the beneficial if the project remains focused on its reliability of the Shuttle before and after the requirements and can avoid changes imposed Challenger tragedy.) In short, significant risk by external forces. is introduced when relying on a product that If an institution wishes to be supported has not been tested in its working with public funds for a long-duration project, environment, whether it is a new car, a then the institution must be sophisticated complex piece of software, or a spacecraft. enough to plan visible milestones, which are comprehensible to the public, at intervals 2.5.3 Political Viability and Social appropriate to the funding review process. Concerns Historically, NASA has been reasonably The human exploration of Mars is likely successful at maintaining funding of decade- to be undertaken for many of the reasons long programs in the face of an annual budget already cited as well as others not presented review. The vast majority of the programs are here. To a large degree, the responsibility for understood by all to have a finite duration. taking action based on these reasons is in the After a satellite has been launched and realm of political decision makers as opposed operated for a given period of time, it either to commercial concerns or other spheres of fails or is shut off. Neither NASA nor the U.S. influence. Thus, support for this type of Congress are yet comfortable with open- program must be sustained in the political ended programs such as the Shuttle or environment for a decade or more in the face International Space Station or human of competition for the resources needed to settlement of the solar system. carry it out. The decades-long time frame for human Perhaps the closest analogy to a possible exploration of Mars cannot be supported until international Mars exploration program is the the role of the space program is well International Space Station, which has been integrated into the national space agenda and an approved international flight program for the exploration of space is no longer over 10 years. During those 10 years, the considered a subsidy of the aerospace configuration of the Station has changed industry. To accomplish this, the space several times and the number of and level of program must show concern for national and commitment from partners has changed international needs (visible contributions to significantly. Also during this time, Russia, technology, science, environmental studies, initially a significant competitor, has turned education, inspiration of youth, etc.) while into one of the larger partners in the maintaining a thoughtful and challenging endeavor. And all of this has taken place prior agenda of human exploration of space in to launching the first element of the Station. which the public can feel a partnership.

2-22 Finally there is the political concern of 2.7 References back-contamination of Earth. This is as much Bogard, D. and P. Johnson, “Martian a social issue as a technical one. Some Gases in an Antarctic Meteorite,” Science, segments of the population will object to any Vol. 221, pp. 651-654, 1983. Mars mission on these grounds. The two tenets of a successful defense against such Duke, M. and N. Budden, “Results, opposition are to ensure that prudent steps Proceedings and Analysis of the Mars are taken at all phases of the project to Exploration Workshop,” JSC-26001, minimize risks and to demonstrate that the NASA, Johnson Space Center, Houston, value of the mission is high enough to merit Texas, August 1992. the residual minuscule risk. Exobiology Program Office, “An Exobiological Strategy for Mars 2.6 Summary Exploration,” NASA SP-530, NASA This section has woven together several Headquarters, Washington, DC, April key elements of a rationale for undertaking 1995. the Reference Mission: human evolution, McSween, H., “What We Have Learned comparative planetology, international About Mars From SNC Meteorites,” cooperation, technology advancement, Meteoritics, Vol. 29, pp. 757-779, 1994. inspiration, and investment. Several Mendell, W., “Lunar Base as a Precursor challenging aspects must be resolved before to Mars Exploration and Settlement,” 42nd the first human crews can be sent to Mars. But Congress of the International Astronautical the Reference Mission has a longer range Federation, IAF-91-704, Montreal, Canada, view and purpose that makes these October 5-11, 1991. challenges worth the effort to overcome. If, at some future time, a self-sufficient settlement Sullivan, T., D. Linne, L. Bryant, and K. is established on Mars, with the capability of Kennedy, “In Situ-Produced Methane and internal growth without massive imports Methane/Carbon Monoxide Mixtures for from Earth, the benefit will be to the eventual Return Propulsion from Mars,” Journal of descendants of the first settlers, who will have Propulsion and Power, Vol. 11, No. 5, pp. totally different lives and perspectives 1056-1062, 1995. because of the initial investment made by Synthesis Group, “America at the their ancestors. Threshold: Report of the Synthesis Group on America’s Space Exploration Initiative,” U.S. Government Printing Office, Washington, DC, May, 1991.

2-23 3. Mission and System Overview

3-1 3-2 3.1 Introduction An infinite number of designs are possible for a mission of this type. The Previous studies of human exploration of approach taken here is based on two general Mars have tended to focus on spacecraft and principles. flight, rather than on what the crew would do on the surface. The Reference Mission takes •A hierarchy of requirements (starting the point of view that surface exploration is from mission objectives) is followed, the key to the mission, both for science and which, as they gain greater depth and for evaluation of the potential for settlement. definition, merge with the proposed As a consequence, the Reference Mission implementation through a set of system architecture allows for a robust surface specifications (note that the Reference capability with significant performance Mission has followed these requirements margins: crews will explore in the vicinity of down to the system level only). the outpost out to a few hundred kilometers, •A reasonable number of alternatives will will be able to study materials in situ and in a be considered, through trade studies at surface laboratory, and will iterate their each level of definition allowing findings with their exploration plan. In comparisons and choices. addition, the development and demonstration of the key technologies required to test 3.1.1 Mission Objectives settlement issues will provide a substantial workload. To make surface exploration Section 1 of this report discussed a series effective, the supporting systems (such as of workshops conducted by NASA to define a EMU, life support, vehicles, robotics) must be set of objectives and supporting rationale for highly reliable, highly autonomous, and a Mars exploration program. The workshop highly responsive to the needs of the crew. attendees (see Table 2-1) identified and Some needs may not be anticipated during recommended for adoption three objectives crew preparation and training, which will for analysis of a Mars exploration program significantly challenge the management and and the first piloted missions in that program. operations systems.

3-3 They are to conduct: 3.1.2 Surface Mission Implementation Requirements •Human missions to Mars and verify that people can ultimately inhabit Mars. To satisfy the objectives for the Reference Mission, the Mars Study Team developed a •Applied scientific research for using series of capabilities and demonstrations that martian resources to augment life- should be accomplished during surface sustaining systems. mission activities. Table 3.1 defines the •Basic scientific research to gain new activities and capabilities that must exist to knowledge about the solar system’s meet the first three program objectives to the origin and history. next level of detail. The three objectives added by the Study Team are useful in selecting A Mars Study Team composed of NASA among feasible mission implementation personnel representing most NASA field options that could be put forth to satisfy the centers (see Table 2-2) used inputs from the capabilities and demonstrations listed in the adopted objectives to construct the Reference table. Mission. In addition, the Study Team recognized that past mission studies had 3.1.2.1 Conduct Human Missions to Mars characterized piloted Mars missions as inherently difficult and exorbitantly From the point of view of the surface expensive. Therefore, the Mars Study Team mission, conducting human missions implies added three objectives. These were to: that the capability for humans to live and work effectively on the surface of Mars must •Challenge the notion that human be demonstrated. This includes several sub- exploration of Mars is a 30-year program objectives to: that will cost hundreds of billions of dollars. •Define a set of tasks of value for humans to perform on Mars and provide the •Challenge the traditional technical tools to carry out the tasks. obstacles associated with sending humans to Mars. •Support the humans with highly reliable systems. •Identify relevant technology development and investment •Provide a risk environment that will opportunities. maximize the probability of accomplishing mission objectives.

•Provide both the capability and the rationale to continue the surface exploration beyond the first mission.

3-4 Table 3-1 Capabilities and Demonstrations for Surface Mission Activities

Conduct Human Missions to Mars a. Land people on Mars and return them safely to Earth. b. Effectively perform useful work on the surface of Mars. c. Support people on Mars for 2 years or more without resupply. d. Support people away from Earth for periods of time consistent with Mars mission durationss (2 to 3 years) e. Manage space operations capabilities including communications, data management, and operations planning to accommodate both routine and contingency mission operational situations; and understand abort modes from surface or space contingencies. f. Identify the characteristics of space transportation and surface operations systems consistent with sustaining a long-term program at affordable cost. Conduct Applied Science Research to Use Mars Resources to Augment Life-Sustaining Systems a. Catalog the global distribution of life support, propellant, and construction materials (hydrogen, oxygen, nitrogen, phosphorous, potassium, magnesium, iron, etc.) on Mars. b. Develop effective system designs and processes for using in situ materials to replace products that otherwise would have to be provided from Earth. Conduct Basic Science Research to Gain New Knowledge About the Solar System’s Origin and History a. Using robotic and human investigations, gain significant insights into the history of the atmosphere, the planet’s geological evolution, and the possible evolution of life. b. Identify suitable venues at Mars, in the martian system, and during Earth-Mars transits for other science measurements.

These then require a set of functional effective system designs be developed and capabilities on the surface, including habitats, demonstrated to extract and use indigenous surface mobility systems, and supporting resources. Opportunities exist to use systems (such as power and communications indigenous resources as demonstrations in systems). the life support subsystem, in energy systems as fuel or energy storage, and as propellant 3.1.2.2 Conduct Applied Scientific Research for spacecraft. These may eventually develop to Use Mars Resources to Augment Life- into essential systems for the preservation of Sustaining Systems the outpost. In addition, the following This objective will require that an habitation activities and demonstrations assessment be made of the location and satisfy the first and second objectives. availability of specific resources (such as •Demonstrate that martian habitability water) that are useful for human habitation or has no fundamental limitations due to transportation. It will also require that uniquely martian characteristics such as

3-5 low gravity, absence of a magnetic field, additional systems for producing food and soil toxicity, or the radiation recycling air and water. environment. 3.1.2.3 Conduct Basic Scientific Research to •Demonstrate that self-sufficiency can be Gain New Knowledge About the Solar achieved on the local scale of a Mars System’s Origin and History base. This includes providing a reasonable quality of life and reasonably This will require that a variety of low risk for the crews, and should scientific explorations and laboratory include operating a bioregenerative life assessments be carried out on the surface of support system capable of producing Mars by both humans and robots. The food and recycling air and water. scientific research will not be conducted completely at any one site, which will create a •Determine the potential for expansion of need for crew member mobility and base capabilities using indigenous transportation systems to support resources. This would include the exploration, the specialized tools required successful extraction of life support outside the outpost to collect and document consumables from the martian materials, and the facilities inside the outpost environment and storage for later use. to perform analyses. •Investigate the biological adaptation of The principal science activities and representative plant, animal, and demonstrations for Mars exploration include microbial species to the martian answering the following questions. environment over multiple generations. •Has Mars been a home for life? These activities and demonstrations are aimed at establishing the feasibility and This set of objectives will combine field approach required to move beyond the and laboratory investigations in geology, exploratory phase toward the development of paleontology, biology, and chemistry. The long-term activities on the planet. They underlying assumption is that this question influence the selection of elements that are will not have been answered by previous included in the surface systems (habitats, robotic Mars exploration programs, and the mobility, life support, power, and best way to get an answer is through communications systems). judicious use of humans on Mars as field geologists and laboratory analysts. Recent To the support facilities identified in the evidence indicating past life on Mars found in previous section must be added exploration a martian meteorite has placed increased systems (orbital or surface), resource emphasis on this question (McKay, et al., extraction and handling systems, and 1996).

3-6 •What are the origin and evolution of rover sample collectors having accessibility to Mars, particularly its atmosphere, and interesting or significant sites at increasing what does it tell us about Earth? distances from the outpost. Figure 3-1 shows a photomosaic of the Candor region of the This set of objectives involves geology Valles Marineris in which the location of an and geophysics, atmospheric science, outpost could address fundamental questions meteorology and climatology, and chemistry. of Mars’ origin and history. This region is Iterative sampling of geological units will be located roughly between 70 degrees and 75 required as well as monitoring of a global degrees west longitude and between 2.5 network of meteorological stations. (A global degrees and 7.5 degrees south latitude. A network will most likely be established by general geological map of the region of the robotic elements of the program.) outpost site should be prepared using data •What resources are available on Mars? gathered by robotic missions prior to selecting The resource discovery and verification and occupying the initial site. of accessibility will require investigations in Once the outpost is established, geology, atmospheric science, and chemistry. exploration activity will consist of surface A general strategy for accomplishing this will observations made by robotic vehicles and begin with a global mapping (from orbit) of human explorers, collection of samples, and selected elemental and mineralogical examination of samples in the outpost abundances. This activity is best suited for a laboratory. Crews will be given broadly stated robotic spacecraft sent prior to the flight of scientific questions or exploration objectives the first human crew. Robotic missions are to be addressed in relatively large regions also likely for verifying the abundances and near the outpost site. Operations will not be making an initial assessment of accessibility as highly choreographed over the 600-day of the resources. The data gathered will also surface stay-time as they are for current be important for selecting likely sites for the spaceflight missions. The crews and Earth- surface outpost to be used by human crews. based supporting investigators will plan campaigns lasting days or weeks, eventually 3.1.2.4 Surface Operations Philosophy extending to months, but always with the In addition to the facilities and assumption that replanning may be necessary equipment mentioned above, the crew must based on discoveries made. It is likely that a have a general operating philosophy for strategy of general reconnaissance followed conducting activities, demonstrations, and by detailed investigations will be followed. experiments on the surface. The targeted The outpost laboratory will be outfitted to investigations to be carried out from the Mars provide mineralogical and chemical analyses outpost depend on humans and automated and, depending on technical development, it

3-7 Desired Landing Area

Figure 3-1 A regional map illustrating potential locations for a Mars outpost.

3-8 may be possible to perform simple kinds of Information will be transmitted to geochronologic analysis. The purpose of these scientists on Earth so they can studies will be to support the field participate in the replanning activity. investigations, answer “sharper” questions, Crews will also emplace geophysical and and allow human explorers to narrow their meteorological instruments to measure focus to the sites of optimum sample internal properties and atmospheric collection. Ultimately, selected samples will dynamics. Drilling short depths into the be returned to Earth for more detailed surface should be standard capability. At analysis. some point it will be appropriate to drill deeply into the surface to address Science equipment, experiments, and stratigraphic issues and to locate and tap tools must be proven in order for the into water reservoirs. exploration and science objectives of the missions to be accomplished, and their •The Mars crews will also have the selection is at the core of the argument that capability to operate telerobotic systems humans can effectively perform scientific conducting even broader exploratory research on the planet. Failure to equip tasks using the ability to communicate humans properly will be a failure to take with and direct these systems in near advantage of their unique potential. Over- real-time. Some teleoperated rovers equipping them may be counterproductive as (TROVs) may be emplaced before crews well, at least from the cost aspect of arrive on Mars and may collect samples transporting unneeded equipment to Mars. for assembly at the Mars outpost. The The exploration and science objectives to be TROVs may be designed to provide performed on the surface can be broken into global access and may be able to return four categories: field work, telerobotic samples to the outpost from hundreds of exploration, laboratory and intravehicular kilometers distance from the site. These activity experiments, and preparation of robotic systems may also emplace materials for return to Earth. geophysical monitoring equipment such as seismometers and meteorological •Observations related to exobiology, stations. geology, and martian atmosphere studies will be made by humans in the field. •Scientific experiments will also be Samples and data will be collected and conducted that are uniquely suited to returned to the outpost laboratory for being performed on the surface of Mars. analysis. The information from the These will typically be experiments that analyses will be used to plan or replan make use of the natural martian future traverses as scientific and environment (including reduced gravity) exploration questions are sharpened. or involve interaction with martian

3-9 surface materials. Studies will be weeks and using mobile facilities, may be performed on biological systems, best conducted at intervals of a few months. performed in conjunction with an Between these explorations, analysis in the experimental bioregenerative life laboratory will continue. The crew will also support system. The deployment of a spend a significant portion of time bioregenerative life support capability maintaining and ensuring the continuing will be an early activity after crew functionality of life support and materials landing. Although this system is not processing systems and performing required to maintain the health and maintenance on robotic vehicles and EVA vitality of the crew, it will improve the suits (systems should be designed to help robustness of the life support system and keep these activities to a minimum). is important to the early objectives of the Crew activities related to living on outpost. Field samples will be studied in another planet should be viewed not only as laboratory facilities shared between the experiments but also as activities necessary to geosciences, biosciences, and facilities carry out the mission. With minor support systems. For example, analytical modifications in hardware and software, systems used to monitor organisms in ordinary experiences can be used to provide the biological life support system may objective databases for understanding the also be used to monitor the environment requirements for human settlement. of the habitat in general. Some analytical capabilities (such as gas To optimize the performance of the chromatographs) find use in both mission, it will be necessary to pick a landing geological and biological analysis. All site primarily on the basis of satisfying samples and data (geological, biological, mission objectives. However, the landing site medical, etc.) will be documented and must be consistent with landing and surface cataloged for later research. operational safety. Detailed maps of candidate landing sites should be available to define the •One crew task will be to select and safety and operational hazards of the site, as package samples for return to Earth for well as to confirm access (by humans or more detailed study. This will require the robotic vehicles) to scientifically interesting creation of a minicuratorial facility and locations. Depending on the results of prior procedures to ensure that missions, it would be desirable to site the uncontaminated samples are returned to outpost where water can be readily extracted Earth. from minerals or from subsurface deposits. As experience grows, the range of human exploration will grow from the local to the regional. Regional expeditions, lasting several

3-10 3.1.3 Ground Rules and Assumptions systems can potentially reduce the total Translating these goals and objectives program costs and enhance crew safety into specific missions and systems required and system maintainability. adopting a number of guidelines and •Provide a flexible implementation assumptions. strategy. Mars missions are complex, so •Balance technical, programmatic, multiple pathways to the desired mission, and safety risks. Mars objectives have considerable value in exploration will not be without risks. ensuring mission success. However, the risk mitigation philosophy •Limit the length of time the crew is as well as the acceptability of the mission continuously exposed to the concept to the public, its elected leaders, interplanetary space environment. Doing and the crews will be critically important this will reduce the physiological and in the technical and fiscal feasibility of psychological effects on the crew and these missions. Mars is not “3 days enhance their safety and productivity. In away,” and overcoming the temptation addition, the associated life science to look back to Earth to resolve each concerns are partially mitigated. It is contingency situation may be the most assumed that crews will arrive at Mars challenging obstacle to overcome in in good health, that full physical embarking upon the human exploration capability can be achieved within a few of Mars. days, and that crew health and •Provide an operationally simple mission performance can be maintained approach emphasizing the judicious use throughout the expedition. of common systems. For example, an •Define a robust planetary surface integrated mission in which a single exploration capacity capable of safely spacecraft with all elements needed to and productively supporting crews on carry out the complete mission is the surface of Mars for 500 to 600 days launched from Earth and lands on Mars each mission. The provision of a robust to conduct the long exploration program surface capability is a defining is not feasible due to launch mass characteristic of the Reference Mission considerations alone. It is necessary to philosophy. This is in contrast to determine the simplest and most reliable previous mission studies that have set of operations in space or on the adopted short stay-times for the first or surface of Mars to bring all of the first few human exploration missions necessary resources to the surface where and focused attention principally on they are to be used. A strategy space transportation. emphasizing multiple uses for single

3-11 •Be able to live off the land. The transit times for the crew or increased capability to manufacture resources at payload delivery capacity for cargo. This Mars, particularly propellants, has long enhances program flexibility. been known to have significant leverage •Examine at least three human missions in terms of the amount of material that to Mars. The initial investment to send a must be launched from Earth. It also human crew to Mars is sufficient to provides a risk reduction mechanism for warrant more than one or two missions. the crew when viewed as a cache of life Each mission will return to the site of the support consumables to back up those initial mission, with missions two and brought from Earth. Additional system three launching in the 2012 and 2014 development effort will be required, but launch opportunities, respectively. This the advantages outweigh the cost and approach permits an evolutionary development risk, particularly if the establishment of capabilities on the Mars infrastructure supports more than one surface and is consistent with the stated human exploration expedition. goals for human exploration of Mars. •Rely on reasonable advances in Although it is arguable that scientific automation to perform a significant data could be enhanced by landing each amount of the routine activities human mission at a different surface site, throughout the mission. This includes a the goal of understanding how humans capability to land, set up, operate, and could inhabit Mars seems more logically maintain many of the Mars surface directed toward a single outpost systems needed by the crew prior to approach. This leaves global exploration their arrival. to robotic explorers or perhaps later human missions. •Ensure that management techniques are available and can be designed into a 3.2 Risks and Risk Mitigation program implementation that can Strategy substantially reduce costs. Several related but also separable aspects •Use the Earth-Mars launch opportunities of risk are associated with a Mars mission and occurring from 2007 through 2014. A must be considered in designing the 2009 launch represents the most difficult Reference Mission. Reference Mission opportunity in the 15-year Earth-Mars activities will inevitably be hazardous trajectory cycle. By designing the space because they are conducted far from home in transportation systems for this extreme environments. However, the hazards opportunity, particularly those systems can be reduced by proper design and associated with human flights, they can operational protocols. Before a Mars be flown in any opportunity with faster

3-12 exploration program is approved, it will be However, there are important and potentially necessary to decide whether the elements of deadly environmental hazards (such as risk to the enterprise can be reduced to a level radiation and meteoroid damage) which must consistent with the investment in resources be addressed. Two radiation hazards exist. and human lives. First and most dangerous is the probability of a solar proton event (SPE) which is likely to 3.2.1 Risks to Human Life occur during any Mars mission. Solar proton Crews undertaking the human events can rise to the level where an unshield- exploration of Mars will encounter the active ed person can acquire a life threatening space environment, the in-space environment, radiation dosage. However, shielding with and the planetary surface environment. modest amounts of protective material can alleviate this problem. The task becomes one The active space environment includes of monitoring for events and taking shelter at launch from Earth, maneuvers in near-Earth the appropriate time. Galactic cosmic rays, the space, launch on a trajectory to Mars, entry other radiation hazard, occur in small and landing on Mars, launch from Mars, Mars numbers, are very energetic, and can cause orbital maneuvers, launch on a trajectory to deleterious effects over a long period of time. Earth, reentry of Earth’s atmosphere, and For astronauts in LEO, exposure to cosmic landing on Earth. Because these are energetic radiation has been limited to that level which events, the risk is relatively high. In 100 could induce an additional 3 percent lifetime launches of United States manned spacecraft risk of cancer (curable or incurable). Because and a similar number of Russian spacecraft, of a policy that radiation hazards should be the only fatal accidents have occurred in kept as low as reasonably achievable, space- launch or landing. Once in space, the craft and space operations must be designed environment has been relatively benign. to minimize exposure to cosmic rays. The (Apollo 13 was an exception. En route to the health risk today from radiation exposure on moon, it experienced an equipment failure a trip to Mars cannot be calculated with an which jeopardized the crew. Because of the accuracy greater than perhaps a factor of 10. characteristics of the Earth-Moon trajectories The biomedical program at NASA has given and the spacecraft design, it was possible to high priority to acquiring the necessary health recover the crew. This type of risk can be data on HZE radiation, including the design addressed in part by the Mars exploration shielding materials, radiation protectant architecture, and can be different for humans materials, and SPE monitoring and warning and cargo.) systems for the Mars crew. (For additional The quiescent in-space environment is discussion and explanation of this topic, see relatively benign from the point of view of NASA, 1992; Townsend, et al., 1990; and explosions and other spacecraft accidents. Simonsen, et al., 1990.)

3-13 The planetary surface is the third trip to and from Mars, without accomplishing environment which provides risks to crews. any surface exploration objectives, would be Because operational experience on Mars is only minimally successful. Mission risk is limited, this environment is the least related to the integrated capability of the crew understood. As the objective of human and their systems to conduct the mission. For exploration of Mars will be to spend time on the crew or the systems to fail to perform puts the surface of Mars, extensive EVA will be the mission at risk of failure. On the human required as part of the mission. EVAs will side, this requires attention to health, safety, involve exiting and reentering pressurized performance, and other attributes of a habitats and conducting a variety of activities productive crew. On the system side, this on the surface in space suits or other requires that systems have low failure rates, enclosures (including vehicles). In this area, have robust backups for systems that may fail accidents and equipment failures are the or require repair, and be able to operate biggest concerns. These risks must be successfully for the required period of the addressed by examining a combination of mission. Strategies to minimize failure can be detailed information about the surface designed at the architecture level or at the environment, designing and testing system level. hardware, and training the crew. To some extent, EVA can be reduced or simplified by 3.2.3 Risks to Program Success using telerobotic aids operated by the crew Program risk is a term that refers to the from their habitat. (The risks associated with programmatic viability of the exploration the habitat itself are probably similar to those program—that is, once the program has been faced in free space, with somewhat more approved, what are the risks that it will not be benign radiation and thermal environments.) completed and the exploration not Finally, the presence of dust on Mars will undertaken? These are programmatic issues present risks, or at least annoyances, to that in many cases seem less tractable than surface operations. Robotic missions to Mars the technical risks. They can be influenced prior to human expeditions should improve when management of the enterprise fails to understanding of the surface hazards crews meet milestones on schedule and cost, when will encounter. unforeseen technical difficulties arise, or when political or economic conditions 3.2.2 Risks to Mission Success change. They can be mitigated by sound The risk of a Mars exploration mission is program management, good planning, and measured by the degree to which the program advocacy or constituency building on the objectives can be accomplished. A successful political side.

3-14 3.2.4 Risk Mitigation Strategy suitable suite of replacement systems as The riskiest part of the first exploration backups to the prime systems. The following missions to Mars may well be the risk of priorities are recommended. accident on launch from Earth, and the •Crew health and safety are top priority energetic events of launches and landings for all mission elements and operations; during other phases of the mission are likely life-critical systems are those absolutely to make up the remaining high risk parts of required to ensure the crew’s survival. the mission. Yet, the environment on the This implies that life-critical systems will surface of Mars will be new and untried, the have two backup levels of functional missions will be long, and the opportunities redundancy; if the first two levels fail, the to make up for error small. Therefore, a crew will not be in jeopardy but will not conscious approach to minimizing risks on be able to complete all mission objectives. the martian surface must be adopted. For a At least the first level of backup is starting point, it is assumed that this risk automated. (This is a fail operational/fail must be smaller than the combined risks of all operational/fail-safe system.) of the energetic events. Design requirements •Completing the defined mission to a will have been developed with this in mind. satisfactory and productive level The strategy for reduction of risks on the (mission-critical) is the second priority. surface involves four levels of consideration. This implies that mission-critical At the top level, the mission architecture objectives will have one automated provides for assurance that all systems will backup level. (This is a fail operational/ operate before crews are launched from Earth. fail-safe system.) The strategy must be flexible in allowing •Completing additional, possibly subsequent robotic missions to replace any unpredicted (mission-discretionary), systems shown not to be functional prior to tasks which add to the total productivity sending crew. This, in turn, places design of the mission is third priority. The crew requirements on the hardware to allow will not be in jeopardy if the mission- problems to be identified, isolated, fixed in discretionary systems fail, and a backup place if possible, and bypassed if necessary is not needed. (This is a fail-safe system.) through the addition of a parallel capability sent on a subsequent flight. The systems contributing to this backup strategy were assumed to be provided by The second level of risk reduction either real redundancy (multiple systems of involves providing redundancy through the the same type) or functional redundancy overlapping functional capabilities between (systems of a different type which provide the various systems, the ability to repair any life- required function). Recoverability or critical systems, and the provision of a

3-15 reparability by the crew will provide yet be prepared to complete the full mission additional safety margins. without further resupply from Earth. Unlimited resources cannot be provided The third level of risk reduction involves within the constraints of budgets and mission the automation of systems including fault performance. Their resources will either be detection, failure projection, and maintenance with them or will have already been delivered activities, and the provision of data that to or produced on Mars. So trade-offs must be demonstrate current status and predict future made between cost and comfort as well as states. Such systems are not only conservative performance and risk. Crew self-sufficiency is of crew time, but also more effective and required because of the long duration of their precise, particularly on routine monitoring mission and the fact that their distance from and control tasks. Earth impedes or makes impossible the The fourth level of risk reduction is traditional level of communications and related to crew training and proficiency. The support by controllers on Earth. The crews biggest concern in this area is that the crew will need their own skills and training and will be away from the traditional Earth-based specialized support systems to meet the new training environment for years at a time. challenges of the missions. Those areas with direct human Crews should be selected who will agree involvement—EVA, life support systems, to conduct operational research willingly and high capacity power systems, propellant openly. Crew members should be selected production and storage, mobile vehicles, and who can relate their experiences back to Earth other complex facilities—all carry a high risk in an articulate and interesting manner, and for accident, particularly if training is not they should be given enough free time to recent or crew members become appreciate the experience and the opportunity overconfident. Crews will most likely be to be the first explorers of another planet. required to participate in continuous task training for safety awareness requirements. Because the objectives of the missions are to learn about Mars and its capability to 3.3 Flight Crew support humans in the future, there will be a minimum level of accomplishment below Humans are the most valuable mission which a viable program is not possible. asset for Mars exploration and must not Survival of humans on the trip there and back become the weak link. The objective for is not a sufficient program objective. humans to spend up to 600 days on the martian surface places unprecedented 3.3.1 Crew Composition requirements on the people and their supporting systems. Once committed to the The number of crew members to be taken mission on launch from LEO, the crew must to Mars is an extremely important parameter

3-16 for system design, because the scale of the lists of required skills were developed. habitats, space transportation system, and Expertise is required in three principal areas. other systems supporting the mission are •Command, control, and vehicle and directly related to the number of crew facility operations functions. These members. This, in turn, will have a direct functions include command, relationship to the cost of the first missions. management, and routine and The size of the crew also is probably inversely contingency operations (piloting and proportional to the amount of new navigation, system operations, technology which must be developed to allow housekeeping, maintenance, and repair all tasks to be performed. Because of of systems). Maintenance must be communication time delays between Earth accomplished for facility systems, and Mars, some functions that have human support systems (medical previously been performed by people on facilities, exercise equipment, etc.), EVA Earth will be carried out autonomously or by systems, and science equipment. crew members. Generally, there will be a high degree of automation required for routine •Scientific exploration and analysis. This operations on the Mars journey to allow crew area includes field and laboratory tasks members to do specialized tasks. in geology, geochemistry, paleontology, or other disciplines associated with For the Reference Mission study, it was answering the principal scientific assumed that crew health and safety are of questions. first priority in successfully achieving mission objectives and that the surface system design •Habitability tasks. These tasks include requirements for operability, self-monitoring, providing medical support; operating maintenance, and repair will be consistent the bioregenerative life support system with the identified minimum number of crew experiment; performing biological, members. The crew size and composition was botanical, agronomy, and ecology determined in a top-down manner (objectives investigations; and conducting other ➝ functions ➝ skills ➝ number of crew experiments directed at the long-term members + system requirements) as the viability of human settlements on Mars. systems have not been defined in a bottoms- The types of crew skills needed are up manner based on an operational analysis shown in Table 3-2 (Clearwater, 1993). If each of the system. skill is represented by one crew member, the The Mars Study Team workload analysis crew size would be too large. Personnel will assumed that the crew would spend available have to be trained or provided the tools to time in either scientific endeavors or perform tasks which are not their specialty. habitation-related tasks. From that analysis,

3-17 Table 3-2 Surface Mission Skills

Specialized Operations Focused and Services Objectives In-Common

Mechanical Systems Operations, Geology Management/planning Maintenance and Repair Geochemistry Communications Paleontology Computer Sciences Tool-Making Geophysics including Database Management Meteorology and Atmospheric Science Electrical Systems Operations, Food Preparation Maintenance and Repair • routine greenhouse Biology Electronics Systems Operations, operations Maintenance and Repair Botany • plants to ingredients Ecology • ingredients to food Agronomy Social Science Vehicle Control Navigation Teleoperated Rover Control

General Practice Medicine Surgery Biomedicine Journalism Psychology Psychology Housekeeping

Special skill requirements appear to be in the procedures under the direction of areas of medicine, engineering, and medical experts on Earth (through geoscience. telemedicine).

•Medical treatment. In a 3-year mission, it •Engineer or technician. A person skilled is very likely that an accident or disease in diagnosing, maintaining, and will occur. At least one medically trained repairing mechanical and electrical person will be required as well as a equipment will be essential. A high backup who is capable of conducting degree of system autonomy, self- diagnosis, and self-repair is assumed for electronic systems; however, the skill to

3-18 identify and fix problems, in conjunction and a minimum number of crew with expert personnel on Earth, has been members will be required by the repeatedly demonstrated to be essential distribution of tasks. For example, EVAs for space missions. are likely to require at least two people outside the habitat at any one time in •Geologist-Biologist. A skilled field order to assist each other. A third person observer-geologist-biologist is essential is likely to be required inside to monitor to manage the bioregenerative life the EVA activities and assist if necessary. support system experiment. All crew If other tasks (repair, science, members should be trained observers, bioregenerative life support system should be highly knowledgeable of the operation) are required to be done mission science objectives, and should be simultaneously, the number of crew able to contribute to the mission science. members may need to be increased. Other factors will also contribute to the •Specific contingency situations and final determination of crew size: system mission rules have not been established autonomy, simultaneous operations, for the Reference Mission because it is contingency situations, human factors, and too early in the design phase. However, international participation. the choice of what the crew will be •Electronic and mechanical equipment allowed to do or not do can impact the must be highly autonomous, self- size of the crew. For example, during maintained or crew-maintained, and exploration campaigns, mission rules possibly self-repairing. The amount of may require that some portion of the time taken to do routine operations must crew be left in the main habitat while the be minimized through system design. In remainder of the crew is exploring in the principle, the operation of supporting mobile unit. It will be necessary to have systems (such as power, life support, in a backup crew to operate a rescue situ resource recovery) should be vehicle in case the mobile unit has a transparent to the crew. The best problem. If the exploration crew requires approach in this area is to define the three people, the requirement to have requirement for technological one driver for a backup unit and one left development based on the mission at the outpost implies a crew of not less requirements for a given crew size. than five.

•Simultaneous operations will be •In terms of human factors required during the nominal mission. All considerations, the psychological crew members will be fully occupied adjustment is more favorable in larger during their assigned working hours, crews of six to eight than in smaller

3-19 crews of three to five. However, the success. Therefore, a larger crew may be psychological environment may be met required to address the risk issues. Currently, by system and support provisions rather the Reference Mission is built on the than by the crew size itself. assumption of a crew of six.

•It is conceivable that each country that 3.3.2 Crew Systems Requirements makes a major contribution to an international Mars exploration mission To survive, the crew will need adequate will demand representation on the crew. shelter, including radiation protection; Currently, a Mars crew might be breathable, controlled, uncontaminated patterned after the International Space atmosphere (in habitats, suits, and Station with representatives from the pressurized rovers); food and water; medical United States, Russia, European Space services; psychological support; and waste Agency, and Japan. However, in an management. During the 4- to 6-month transit enterprise of this magnitude, Third to Mars, the chief problems will be World representatives might also be maintaining interpersonal relationships selected by the United Nations. needed for crew productivity and maintaining physical and mental At a summary level, the five most conditioning in preparation for the surface relevant technical fields required by the mission. On the Mars surface, the focus will exploration and habitation requirements turn to productivity in a new and harsh include mechanical engineer, electrical and environment. The transit environment is electronics engineer, geologist, life scientist, likely to be a training and conditioning and physician-psychologist. These fields environment, the surface environment is should be represented by a specialist, with at where the mission-critical tasks will be done. least one other crew member cross-trained as a backup. Crew members would also be For long-duration missions with cross-trained for the responsibilities of a wide inevitably high stress levels, the trade-off variety of support tasks as well as tasks of between cost and crew comfort must be command and communications. weighed with special care. High quality habitats and environmental design features The result of the workload analysis are critical to assuaging stress and increasing indicates that the surface mission can be crew performance—conditions that will conducted with a minimum crew of five, greatly increase the likelihood of mission based on the technical skills required. success. Providing little more than the However, loss or incapacitation of one or capability to survive invites mission failure. more crew members could jeopardize mission Not all amenities need be provided on the first mission. The program should be

3-20 viewed as a sequence of steps which, over member will be from 10 percent to 20 percent time, will increase the amount of habitable of the amount of their time on Mars. space on the surface, increase the amount of Automated or teleoperated rovers could time available to the crew to devote to extend the effective field time by crew mission objectives and personal activities, members. increase the amount of crew autonomy, improve the quality of food, increase access to 3.4 Mission Operations privacy, and increase the quality and quantity Central to the success of the Reference of communications with Earth. In addition, Mission is the accomplishment of all activities experience in Mars surface operations may associated with mission objectives. To this reduce some of the stresses associated with end, crew operations are an essential part of the unfamiliarity of the environment. ensuring program success and must be The quality of life can be enhanced by factored into all aspects of program planning. access to and use of indigenous resources. In All crew activities throughout each mission, the near term, use of indigenous resources from prelaunch through postlanding, reduces some of the mission risks (creation of constitute crew operations. The majority of caches, use of local resources for radiation crew activities fall into four categories: shielding, etc.). In the long term, use of local training, science and exploration, systems resources may allow more rapid expansion of operation and maintenance, and usable space. Achieving the capability to programmatic. produce water and oxygen from local •Training activities include such areas as resources may have physical and prelaunch survival training for all critical psychological benefits over continued life support systems, operational and recycling (for example, reducing limitations maintenance training on mission-critical on water utilization for hygiene purposes). hardware, prelaunch and in-flight The ability to grow food on site also has an proficiency training for critical mission enhancing psychological effect. The phases, and science and research psychological impacts of these developments training for accomplishing primary is difficult to quantify, however real the effects science objectives. may be. •The majority of science and exploration Finally, crew support by intelligent robots activities will be accomplished on the and automated systems appears to be a good surface of Mars. They include, but are investment from the point of view of total not limited to, teleoperated robotic mission productivity. The workload analysis activities, habitability experiments, local indicates that the total amount of time spent and regional sorties, and planetary in the field (on foot or in a rover) by a crew

3-21 science investigations. Supplemental Extensive training in these areas will improve science objectives may be accomplished overall mission success as well as contribute during other phases of the mission as to meeting science and exploration objectives. well. Several overriding principles must govern the way training is conducted for the Reference •During the first mission, a substantial Mission. Due to time constraints, crew amount of crew time will be spent training in preparation for the first mission operating and maintaining vehicle must be done concurrently with vehicle and systems. This time allocation is expected training facility development. The first crew to decrease with subsequent missions as and mission controllers will be supplanting the systems and operational experience operational training with involvement in base matures. system design and testing. This will provide •Lastly, programmatic activities for the the mission team with the needed system crews include publicity, documentation, familiarity which would otherwise come from reporting, and real-time activity operational training exercises. Operations planning. input on system designs also has the added This report does not make specific benefit of enhancing vehicle functionality and conclusions regarding hardware operability (for example, nominal daily requirements, facilities requirements, and operations such as housekeeping, food training programs, but a number of preparation, and system maintenance will recommendations and guidelines regarding benefit from input by the actual users). these areas have been developed and tailored Additional prelaunch training must to the various mission phases that will be emphasize developing a working knowledge experienced by each crew sent to Mars. While of life-critical and mission-critical elements. these and other crew activities may not be Because reliance on Earth-based ground seen as directly affecting program success, all control becomes more difficult and less time- areas contribute to the successful completion responsive as the mission progresses toward of each mission and are, therefore, essential to Mars, crew self-sufficiency becomes essential. the overall success of the Reference Mission. In-depth training on life-critical and mission- critical systems will enable crews to become 3.4.1 Training Guidelines more self-sufficient. Contingency survival The key to successful operations is training for failures in critical life support having well prepared, knowledgeable team systems will also be required as real-time members. This knowledge and preparation is ground support will not be possible during most effectively obtained by training for Mars surface operations and similar remote nominal and contingency operations. phases of flight.

3-22 Extensive preflight and in-flight training critical events will ensure that crews are on critical event activities (such as major adequately prepared for both nominal and propulsive maneuvers, Mars atmospheric contingency situations. From Earth launch entry, surface sorties, and Earth atmospheric until Mars ascent and TEI is about 2 years entry) will be required to ensure crew which necessitates an ongoing training proficiency during these busy time periods. regime to maintain proficiency. The Earth- The need for such training will require based training the crews received 2 years preflight development of a well-defined earlier prior to Earth launch will not be activity plan for all critical events. sufficient. Training for the Mars atmospheric Significantly less preflight training will be entry and landing phase will be conducted by required for noncritical, mission-success- the crew during the transit between Earth and oriented activities such as surface science Mars. While on the martian surface and operations. The initial surface operations intermixed with other surface activities, the required for the establishment of the Mars crew will conduct proficiency training for the surface base and preliminary surface science critical Mars ascent phase, subsequent activities will be well defined before the first docking with the ERV, and trans-Earth crew departs. Subsequent exploration and propulsive maneuver. In-flight and surface science activities will depend on the findings training requirements dictate the need for from the initial scientific investigations. As a effective training facilities in the habitat result, training for more than the initial vehicles or in the ascent vehicles. Design and science activities will not be feasible. Instead, development of such facilities will require it will be necessary to ensure that crews have further investigation and is beyond the scope the skills to enable them to plan and prioritize of this preliminary report. real-time activities in support of the overall Documentation in the form of computer- mission objectives. Some planning assistance based libraries must be available for and direction will be provided by ground operational instruction, maintenance of and personnel; however, the responsibility for troubleshooting systems, and hardware detailed planning and execution will reside failures. Reliable and immediate access to this with the crew. They are on the surface and type of information will supplement crew have firsthand knowledge of environmental training for all types of activities from and logistical considerations. mission-discretionary to life-critical. Extensive Due to the length of the mission and computer-based resources will have the length of time between critical event added effect of increasing crew self- activities, proficiency training will be sufficiency during remote mission phases. necessary during all phases of the mission. In The final, but by no means least flight and on the martian surface, training for significant, element of crew training will be

3-23 the feedback provided by the early crews on objectives as well. Detailed identification of training applicability and effectiveness related safety requirements and related activities is to all mission phases. Feedback from the first not required until later in the mission crew in particular will need to be planning process and will not be discussed incorporated into training procedures, here. hardware, and facilities to be used by Subsequent exploration and science subsequent crews. An effective channel for activities will depend on the findings from incorporating this feedback into redesign and the initial scientific investigations. As a result, upgrading of systems and procedures will be it will be necessary for crews to do real-time essential for follow-on crew training. science activity planning to continue research activities. Principal investigators and ground 3.4.2 Science and Exploration support personnel will provide the guidelines The majority of science and exploration for use in planning priorities of mission activities will be accomplished on the surface objectives. However, the detailed procedures of Mars. They include, but are not limited to, for executing science activities must be left, in teleoperated robotic activities, habitability general, to the crews who have firsthand experiments, local and regional sorties, and knowledge of the unique environmental and planetary science investigations. Additional logistical considerations of this mission. science activities which supplement the Additionally, eliminating the excessive primary science objectives may be ground planning and replanning activities accomplished during other phases of the which have been customary for near real-time mission as well; however, the largest portion manned space operations will reduce cost. of time and activity allocated in support of Beyond the initial investigations, several science and exploration will occur on the surface science and exploration activities can planetary surface. be identified preflight as targets for detailed Initial surface science activities will be planning and execution: telerobotic well defined before each crew departs Earth. exploration and local and regional surface Detailed activity planning to maximize the sorties. Such preflight planning will maximize crews useful science and exploration time will the crew’s useful science time, maximize increase overall mission success and will be science return, improve crew safety on necessary to ensure the successful completion difficult exercises, and increase overall of many primary science objectives and mission success. mission safety requirements. Many investigative results designed to satisfy safety requirements (for example, tracking crew health) will contribute to satisfying science

3-24 3.4.3 Systems Operations and Where applicable, autonomous vehicle Maintenance health monitoring and testing will enable During the first mission, a substantial crew members to use their time performing amount of crew time will likely be spent science and exploration activities. In operating and maintaining vehicle systems. conjunction with this automation, access to This time is expected to decrease with hardware and software documentation for all subsequent missions as the systems and systems can expedite operations and operational experience base mature. maintenance activities which require crew However, until that time, the more familiar participation. Additionally, due to large the crews are with all systems, the less time resource requirements, some of the vehicle operations and maintenance will take from operations, such as long-term health science and exploration activities. To enhance monitoring, trend development or prediction, crew familiarity with the numerous vehicle and failure analysis, may be accomplished by systems prior to launch, crews should be ground system support personnel. The involved in the design and testing of primary delineation between which system functions vehicle systems. The resulting intimate are automated, crew-managed, or ground- knowledge of the vehicle systems has the support-managed is not clear and is subject to added benefit of supplementing crew training a host of variables. Some of the considerations on their operational use. Another way to to be used in making this determination are facilitate crew familiarity is to ensure that crew useful time, availability of supporting system designs are modular and easily documentation, knowledge of system repairable. The simpler and more familiar the performance (that is, are we operating outside design, the easier it is to repair and maintain. the envelope?), time criticality of failure recognition and recovery, and constraints on Due to the nature of the Reference development time and cost. General Mission program design (where vehicles are guidelines of responsibility for vehicle placed in a standby mode and subjected to operations are best determined early in the hostile environments for long durations), in- design process as automation of functions depth vehicle and system checkouts will be will affect mission and vehicle design. required periodically. Crew participation in these activities should be minimized but may 3.4.4 Programmatic Activities be necessary due to their access to some of the system hardware. Such access and Programmatic activities for the crews participation may make the crews uniquely include publicity, documentation, reporting, suited for analysis of anomalous results that and real-time activity planning. These types might appear in the system testing. of activities are not usually seen as directly affecting program success. They do, however,

3-25 and if properly planned and coordinated, will political support to programs and contribute enhance crew performance and interaction. to program success. Crew resources from Like vehicle performance, crew performance preflight through postlanding will have to be is key to a successful mission. allocated in support of this activity.

Successful team performance and Another element which contributes to interaction depends on having defined roles program success is the crew feedback on all and responsibilities and the flexibility to aspects of the mission. Their input on system handle real-time events. For complex designs, operations, science activities (for programs like the Reference Mission, this is example, appropriateness, preparedness, important not only among crew member required hardware), and training effectiveness teams, but also among ground support is necessary for the continued improvement personnel teams and between ground support and enhancement of follow-on missions. and the crews. For the crews, knowing who is Along these same lines, documentation of all responsible for what and when makes for activities (such as procedural changes, lessons smoother operations and can alleviate some learned, observations, hardware of the stress associated with long-term, small discrepancies) is a time-consuming but space, personnel interaction. For ground and necessary crew activity. (Using various crew interaction, clear rules governing who is electronic systems rather than similar paper in charge of what activities and who systems for documentation preparation will determines what gets done and when are provide savings in terms of mass, reliability, essential for maximizing mission and science reduced consumables, etc.) Crew records can objective returns and alleviating confusion be used to contribute to mission feedback as especially during remote operations. This will well as documentation. Documentation and enhance operational performance when feedback are important, especially for the first combined with a flexible operational crew, to ensure optimal use of the subsequent architecture allowing crews to create and crew’s time and to enhance the chances of optimize the methods required to handle real- success of future missions of this type. time events and achieve set objectives and goals. (Further discussion on ground 3.4.5 Activity Planning operations and team interaction can be found The level of crew operations in training, in Section 3.8.) science and exploration, systems operations Public affairs activities have been and and maintenance, and programmatic always will be an integral part of crew activities varies throughout different phases activities. While they absorb resources of the mission; however, some characteristics (mostly time), they also bring public and are consistent throughout the phases. For instance, life-critical or mission-critical

3-26 activities, regardless of mission phase, require and the success of mission objectives. detailed planning and precise execution. In Feedback from the crew will be important contrast, non-life-critical or mission-critical during the early phases of this mission, as science and exploration activities may rely on both ground support and flight crew real-time procedures generated by the crew members adapt to the unique environmental whose guidelines for planning will be to and operational challenges of the mission. achieve set mission objectives and goals. Guidelines for crew activity planning must 3.4.5.1 Prelaunch Phase incorporate the flexibility to adapt to the Crew activities during the prelaunch crew’s experience as they learn to live and phase of the mission will concentrate on work in a new environment. training activities for all mission phases. Early In general, crew activity planning must on in the program development, crew be done using a relatively fixed format and involvement in design and testing of primary timeline. This will allow crew members to systems will help facilitate crew familiarity readily adapt to the various environments in with the systems and enhance applicability of which they will be expected to work and live. system designs. The resulting intimate Having regular awake and sleep times, knowledge of the vehicle systems has the consistent meal times, etc., from phase to added benefit of supplementing crew training phase will help the crew adapt to mission on their operational use. Extensive training on phase transitions. Having a consistent length nominal everyday operations (such as workday is also important. With the Mars day housekeeping and food preparation) will also lasting nearly 25 hours, adhering to an Earth- make the crew more comfortable in their based daily schedule of 24 hours would changing environments. Strong emphasis on routinely have the crew awake during critical life support and mission-critical martian night. A consistent 25-hour day systems training will also be required. throughout all phases of flight should be An important part of crew training considered. activities in this prelaunch phase will be A typical work schedule on the Space participation in integrated training activities Shuttle has crew members working with scientists and systems engineers. throughout an entire flight, only getting time Preflight interaction with the science off during extremely long flights (those community, in the form of experimental approaching 2 weeks in duration). For exercises (crews learn to conduct scientific missions that can last a number of years, a investigations) and exploration exercises consistent long-term work schedule must be (crews simulate local and remote sortie developed that will give crew members operations) will enhance overall mission sufficient time off yet maintain productivity success and scientific return. This will benefit

3-27 not only the crew but also the ground science Nominal actions directly associated with the and systems teams by forcing them to interact launch are expected to be minimal. Once in in a way that will be unique to remote orbit, crew activities will center on a complete operations. checkout of vehicle systems prior to leaving Earth orbit while near real-time Crew involvement in integrated training communications with ground support are for critical activities (such as launch, injection possible. This checkout will include all life- phase, Earth orbit systems checkout, Mars critical, mission-critical, and mission- landing phase, return phases) will be needed discretionary systems with appropriate to ensure crew proficiency and performance actions being taken for anomalies on each during these phases. Simulations which stress system according to its criticality. Such a the crew and ground support by introducing checkout, which will be as automated as failures and abort scenarios will help ensure possible, will require some crew and ground crew safety should such instances occur support actions either for testing or for during the mission. troubleshooting failures. In addition to prelaunch training While in Earth orbit but before TMI, activities, extensive medical testing will be limited time or personnel may cause some of required of the crew during this time. Their the less critical pre-TMI testing to be deferred. long- and short-term health will be critical For instance, testing on mission-discretionary factors in the success of this type of long- hardware intended for use only on the duration mission. martian surface may be delayed until later in 3.4.5.2 Earth Launch Phase the transit to Mars. Such decisions will be more appropriately made when vehicle The Earth launch phase is defined as the system checkout requirements are identified crew activities required to support mission during the design process. Additionally, such activities from launch through TMI and real-time decisions may be made based on subsequent powerdown of nonessential assessments of other activities during the hardware. It is expected that some systems Earth orbit phase. used during the launch phase will not be required until later in the mission. The Training activities will not be scheduled hardware which fits in this category will be during the Earth launch through TMI phase placed in a quiescent mode to conserve of the mission as the crew will have been resources. trained for these activities prior to launch. Additionally, with the exception of those During the Earth launch phase of the activities related to crew health maintenance mission, the crew’s primary focus will be to and monitoring, planned science activities ensure a safe launch and Mars injection. will not be performed during this high

3-28 systems activity time frame. Medical testing be made prior to launch based on time or and assistance may be required during this personnel constraints or based on the result of phase as crew members adapt to the change earlier failures. Activities for failure analysis in environment. (The number of crew and troubleshooting will be accomplished on members who typically do not experience an as needed basis. space sickness during the first few days of The relatively quiescent vehicle system weightlessness is just one in three based on activity during the transit phase makes it 171 Shuttle crew members (Reschke, et al., well-suited for crew training activities. 1994).) Any serious life- or mission- During this time, additional training time can threatening crew illness prior to TMI will be be made available for the training above and reason to abort the mission. beyond the preflight training that is required Throughout all mission phases, to maintain crew proficiency during the documentation of activities and feedback on relatively long Mars transit time. The need for training effectiveness will be required of all in-flight training will require that training crew members. This will be essential in order simulators be available to the crew in the to make effective use of the training time of transit-habitat vehicle. Critical events that will the follow-on crew and the program’s require training during this time are MOI, training hardware. Due to the high systems landing, and Mars launch activities. activity during this phase, documentation Additional time may also be made available and other programmatic activities will be for training and review of payload and either minimal or deferred to a later time. science hardware to be used on the surface.

During the transit phase, time may be 3.4.5.3 Trans-Mars Phase available for limited science activities. The The trans-Mars phase of the mission is primary restriction on conducting defined as crew activities from post-TMI interplanetary science activities will likely be system powerdown through Mars Orbit mass related. Interplanetary science Insertion (MOI) preparation. This (astronomy, solar observations) is not the interplanetary transit phase will be fairly primary science objective for this type of homogeneous from the standpoint of mission; and, as such, related hardware will environment and crew activity. Crew only be provided for crew use if mass activities related to vehicle systems are margins exist at the appropriate point in the expected to be minimal. Only nominal design process. However, there may be operations (housekeeping, food preparation, opportunities for useful scientific data return etc.) will be required unless mission- which can “piggy-back” on instruments discretionary systems testing has been provided for crew safety issues. An example postponed until after TMI. This decision may would be conducting some solar science

3-29 experiments as part of meeting requirements and appropriate time must be allocated for crew safety (as in solar flare detection). during the crew schedule for such activities. Also, medical testing will be required periodically throughout this phase to verify 3.4.5.4 Mars Landing Phase crew health. Related studies on crew The Mars landing phase is a very adaptation to the space environment and dynamic phase of the mission and is defined other health-related biomedical science as the time from MOI preparation through experiments may benefit from such testing. postlanding crew recovery and surface As with all mission phases, system activation. Many of the activities documentation of activities and feedback on during this time frame will have been training effectiveness will be required of all planned in detail before launch and perhaps crew members in order to make effective use updated during the interplanetary transit. of the follow-on crew’s training time. Prior to MOI the crew will have to Additionally, the information will provide prepare the transit-habitat vehicle for engineers on Earth with guidelines for transition from a zero-g to a partial-g surface upgrading and improving the vehicle systems vehicle. All peripherals, supplies, and and training hardware. Transit time is ideal hardware that have been taken out for use for documenting current and earlier phases of during transit will have to be safely stowed. the mission. Nonessential equipment will be powered Due to the high interest in such a down in exchange for equipment necessary mission, the crew will be required to for this phase of flight. During this time, the participate in numerous public affairs crew will have to checkout or verify the activities. International participation in this operational status of all hardware and type of mission will only increase press software required for the upcoming critical demands on crew time. Press and crew MOI and landing activities. exchanges will be particularly productive Pre-MOI activities must be initiated early during relatively quiescent periods early in enough to allow sufficient time to the transit phase when communication lag troubleshoot any failures or discrepancies times are short. As communication lag time prior to the critical phase. Many of the increases, the necessity for crew autonomy activities during this phase will, by necessity, will become evident. However, be automated. However, crew intervention communication with Earth will still have to and override must be available due to the be provided for failure assistance and crew uniqueness and criticality of this phase of the personal interaction with Earth. mission (for example, doing critical activities Communication activities will be higher without real-time support in a new and during the initial and critical mission phases, unique environment) and in general as a backup to the automated systems.

3-30 After landing, a thorough vehicle On approach and on the surface of Mars, checkout will be necessary due to the drastic communication lag time with Earth will be transition in operational environment from near or at its maximum. During such a critical vacuum and zero g to a planetary surface phase of flight, crew functions will, of environment. Initially, the only checkout necessity, be virtually autonomous from which will be done will be on those systems Earth-based support. Some communication required to certify that crew safety and life- with Earth will still have to be provided for support systems and their backups are failure assistance and vehicle health operational. monitoring of trend data. Such requirements may drive the need for regular, perhaps Crew training activities during the latter continuous, communications capability with part of the transit phase and the early part of Earth. the landing phase will intensely focus on critical activities for the MOI and landing 3.4.5.5 Mars Surface Phase phase so that the crew is adequately prepared for upcoming events. Again, this will require The Mars surface phase is defined as that adequate training facilities be available to postlanding recovery operations to prelaunch the crew on the transit-habitat vehicle. operations. In general, this phase of the mission will receive a minimal amount of Minimal science activities will be done mission-specific planning and training prior during the Mars landing phase. Time may be to departing Earth; its focus will be on the available for limited orbital observations to mission’s primary science and exploration take advantage of the unique opportunity to activities which will change over time to photograph and gather remotely sensed data accommodate early discoveries. A general of Mars on approach and from orbit. outline of crew activities for this time period However, this will depend on the available will be provided before launch and updated mass allocated for this type of equipment, the during the interplanetary cruise phase. This success of the higher priority critical systems, outline will contain detailed activities to and the training activities during this time ensure initial crew safety, make basic frame. assumptions as to initial science activities, Due to the high systems activity during schedule periodic vehicle and system this phase, documentation and other checkouts, and plan for a certain number of programmatic activities will be minimal. sorties. Much of the detailed activity planning Those activities necessary to improve the while on the surface will be based on initial follow-on crew’s training time and program findings and therefore cannot be training hardware will be deferred until the accomplished before landing on Mars. crew has time available. However, the crew will be provided with

3-31 extensive, but not mission-specific, training operations personnel, crew involvement related to scientific investigation and vehicle provides the crew with confidence in their systems. This will assist the crew in planning return systems, enables visual verification of specific activities in these areas, as required, ascent vehicle system integrity, and allows for while on the martian surface. crew interaction or intervention in anomaly troubleshooting on surface hardware. Beyond Initial postlanding systems activities will annual, comprehensive vehicle checkouts, focus on hardware testing and verification for system activities for the crew will consist of life support, then mission-critical, and finally maintenance, housekeeping, consumables mission-discretionary systems. The initial tracking, and repair operations. phase of these checkouts must be done without the requirement for EVAs. EVAs will Initial science activities during the be restricted until sufficient data have been surface phase will concentrate on verifying collected to fully characterize the immediate crew health and safety on the martian surface. martian environment. Once it has been Atmospheric, chemical, and biological studies confirmed that the martian environment is of the immediate environment surrounding not a threat to crew health or mission success the crew habitat will be critical to ensure crew (assuming this has not been done by prior safety. Once the immediate environment is robotic missions), EVAs may then be characterized and potential threats well accomplished to complete required systems understood, planning for future local and testing and verification. regional sorties may begin. Some general planning of these initial science activities may During the crew stay-time on the surface be done in advance; however, much of the of Mars, additional full-scale testing and crew activity will depend on the initial verification of some hardware will be findings and therefore cannot be prepared required. After vehicle system checkout of the prior to launch. The crew must be provided crew habitat shortly after crew arrival, with enough expertise and applicable activities for joining the crew habitat with a hardware and resources to help them deal previously landed laboratory may begin. with potential unforeseen discoveries and Complete connection of these two vehicles obstacles to their investigations. will be accomplished after a full verification of each vehicle’s individual integrity is Prior to the first EVA and sortie, robotic completed. Also during the initial exploration may map local areas and allow postlanding time frame, verification and investigators to seek out interesting sites for system status check of the vehicles needed for regional sorties. Mission preparation will crew launch and Earth return will be have assumed a minimum number and type required. While much of this activity will be of EVAs; however, adaptation to real-time autonomous and supervised by ground

3-32 discoveries will be necessary for many of Time will also be allocated for public these excursions. affairs events. These types of events will not be interactive due to the time lag, but will be Additional biomedical health science recorded and subsequently transmitted to activities performed on the crew will be Earth. Requests from news media and other required during the surface phase as well. organizations will be reviewed, scheduled, Safety issues, health examinations, and then relayed to the crew through mission investigations to gather data on low-g management personnel on Earth. Activities adaptation, and long-term physiological such as these will require a flexible planning effects on the crew will also be conducted architecture in which crew and ground during the surface phase. support both participate. As with other phases of flight, there may All of the above mentioned surface be opportunities for some scientific data activities will require some level of return which can piggy-back on instruments communication with mission teams on provided for crew safety issues. For instance, Earth—both science and systems teams. limited solar science may be provided in part Analysis of the communication requirements for crew safety issues (as part of solar flare will result from a combination of system data detection), thus providing opportunity for requirements, crew health data requirements, additional solar science observations while on crew personal communications, and science the martian surface. data requirements. Training during surface operations will be periodic to maintain proficiency for 3.4.5.6 Mars Launch Phase mission-critical activities (such as launch and The Mars launch phase is a very dynamic Earth return). Additional training activities, phase of the mission and is defined as the on an as needed basis, may be required for activities from preparation for launch through activities such as sorties and EVAs. TEI and nonessential hardware powerdown. Documentation of activities and feedback Many of the activities during this time frame on training effectiveness will be required of will have been planned in detail prior to all crew members in order to make effective launch from Earth. use of the follow-on crew’s training time. The Before committing the crew to Mars information will provide engineers on Earth ascent and Earth return activities, full systems with guidelines for upgrading and improving checkout of the MAV and ERV is required. the vehicle systems and training hardware. Because both vehicles are critical to crew Additional documentation of scientific safety and survival, sufficient time must be experiments and results will need to be provided prior to launch to verify systems relayed to Earth for use by the science teams and troubleshoot any anomalous indications in analysis and future planning.

3-33 prior to crew use. Additional crew time will During this most critical of time frames, be spent preparing the surface habitat and other activities such as public affairs events other facilities for an untended mode. Such and documentation of activities will be activities will include stowing any minimized. Due to the critical nature of this nonessential hardware, safing critical systems mission phase, communication transmissions and their backups, and performing general to Earth will be necessary for failure housekeeping duties which will facilitate use assistance and vehicle health monitoring. of the facilities by future crews. However, due to the nature of the lag time and the criticality of events, vehicle and crew Once the crew has prepared all surface activities will remain fairly autonomous. equipment for departure, the actual departure activities will begin. Detailed activities for this 3.4.5.7 Trans-Earth Phase departure will have been prepared and simulated on Earth, so a detailed plan for The trans-Earth phase is defined as the Mars launch through TEI will be available post-TEI powerdown through preparation for and executed at the appropriate time. Earth landing. This interplanetary transit Contingency scenarios will also have been phase will be fairly homogeneous from an planned prior to Earth launch, and enough environment and crew activity standpoint. time will be allocated during ascent and The crew activities related to vehicle systems rendezvous activities to enable successful are expected to be minimal. Only those operations within these contingencies. After activities required for nominal operations will successful launch, rendezvous with the return be required (housekeeping, food preparation, vehicle, and TEI, the crew will again place etc.). nonessential hardware in a quiescent mode Crew training activities during this time for the return trip. frame will focus on the critical Earth entry In the time period leading up to the Mars and landing phase of flight. This will drive an launch phase, the crew will spend an ERV hardware requirement to provide the increasing amount of time training and crew with adequate simulators and on-board preparing for this extremely critical phase of training facilities to maintain proficiency in the mission. In particular, the rendezvous vehicle operations. The crew will also begin a with the ERV will require attention. Sufficient regime of zero-g countermeasure activities training facilities must be available on the (such as exercise, lower body negative surface to ensure crew proficiency in these pressure, etc., depending on the best available activities prior to execution. Also, knowledge at the time) to prepare themselves physiological training for the return to a zero- physically for return to a one-g environment. g and eventually a one-g environment will be Again, due to the relatively quiescent dramatically increased during prelaunch. system activity during the transit phase, time

3-34 may be available for the crew to do limited currently known how prolonged low-g and science activities. The restrictions on zero-g environments will affect the human interplanetary science activities will be mass physiology, the main focus of this phase of related. Medical testing will be required flight will be the safe return and recovery of periodically throughout this phase in order to the crew. meet biomedical science objectives and verify Crew activities related to vehicle systems crew health for entry. will be emphasized prior to entry. System During this time frame, documentation checkout will be required with sufficient time activity will be extremely important due to prior to entry to allow for troubleshooting the fact that the next crew will be launched any failures and guarantee a safe crew prior to the return crew’s landing. landing. Upon landing, vehicle safing and Additionally, the information will provide powerdown will be required. Due to the high engineers on Earth with guidelines for probability of lower than normal physical upgrading and improving the vehicle systems capability among the crew, many of the and training hardware. Due to time postlanding system activities should be considerations, some handover automated. documentation for the next crew will have No training or science activities will be been prepared prior to leaving Mars. Final planned during this critical phase of flight. transfer of vehicle status is recommended to Crew health monitoring will be conducted for be direct from crew to crew to prevent the purposes of crew health and safety. Also, confusion and ensure thoroughness. Some due to the time-critical nature of this phase, aspects of the hand over may be filtered documentation will be minimal and will through ground support in order to simplify pertain only to crew preparedness and system communications requirements. performance. Due to the high interest in such a mission, the crew will be required to 3.4.5.9 Postlanding participate in numerous public affairs The postlanding phase of crew activities. Quiescent periods of transit time operations is defined as the activities can provide opportunities for press and crew conducted after vehicle powerdown through interaction. mission termination. In most instances, mission termination will not be a well-defined 3.4.5.8 Earth Entry and Landing time and may be different for different The Earth entry and landing phase is members of the crew as crew involvement in defined as the crew activities which support additional program activities is subject to preentry preparation through landing and various conditions. crew health recovery. Because it is not

3-35 Face-to-face debriefings with the 3.5 Mission Design engineers responsible for individual systems The focus of this section is to describe a and vehicles will be beneficial after landing. feasible sequence of flights on specific Such meetings can be more productive and trajectories with specific systems that provide more information than written accomplish Reference Mission goals and documentation. Feedback on all training objectives. Foremost among the choices that activities and facilities throughout the mission must be made is the type of trajectory to use. will also be beneficial postlanding as it will It must be one that can accomplish mission facilitate the training of follow-on crews. objectives using a reasonable transportation Medical testing after landing will system and at the same time address the risk continue as part of long-term health mitigation strategy and still provide for monitoring. This may be required for an flexibility within a development and flight indefinite period of time. Some effects from program. Other assumptions made that affect the mission may not appear until months or the “how” of mission implementation are even years after the flight phases of the discussed as part of the overall mission mission have ended. Therefore, the crew strategy. With these elements in place, this members should be subject to periodic section presents a discussion that includes medical testing for observation of long-term such information as launch and arrival dates, effects of the mission. It may also be necessary payload manifests, and crew activities for to satisfy quarantine issues, whether real or each flight in the set studied for this Reference political, immediately upon return to Earth. Mission. (Quarantine issues will have to be addressed early in the mission planning phases to 3.5.1 Trajectory Options ensure that adequate facilities are available Trajectory options between Earth and when and if they are needed.) Mars are generally characterized by the Formal documentation of all aspects of length of time spent in the Mars system and the mission will be required of all crew the total round-trip mission time. The first members after landing. Additional emphasis option is typified by short Mars stay-times will be placed on providing engineers on the (typically 30 to 90 days) and relatively short ground with guidelines for upgrading and round-trip mission times (400 to 650 days). improving vehicle systems and training This is often referred to as an opposition-class hardware. mission, although this report has adopted the terminology “short-stay” mission. The Due to the high interest in such a trajectory profile for a typical short-stay mission, the crew will be required to mission is shown in Figure 3-2. This class has participate in many public events and higher propulsive requirements than the often debriefings after they return to Earth.

3-36 MISSION TIMES MISSION TIMES OUTBOUND 224 days OUTBOUND 224 days STAY 458 days STAY 30 days Earth Launch RETURN 237 days RETURN 291 days 1/17/2014 Depart Mars TOTAL MISSION 919 days TOTAL MISSION 545 days 11/30/2015

DEPART γ EARTH 1/15/2014 VENUS FLYBY Earth Return 2/23/2015 7/24/2016

γ

Arrive Mars 8/29/2014 EARTH RETURN 7/14/2015 Figurei6i 3-3 Typical long-stay iifi mission DEPART profile. ARRIVE MARS MARS 9/26/2014 8/27/2014 conjunction-class, although this report has adopted the terminology “long-stay” mission. FigureFi 3-2 5 T Typical i l h tshort-stay t i i mission fil profile. These represent the global minimum-energy solutions for a given launch opportunity. The considered long-stay missions, and typically trajectory profile for a typical long-stay requires a gravity-assisted swingby at Venus mission is shown in Figure 3-3. or the performance of a deep-space Within the long-stay category of propulsive maneuver to reduce total mission missions, the option exists to dramatically energy and constrain Mars and Earth entry decrease the transit times to and from Mars speeds. Short-stay missions always have one through moderate propulsive increases. The short transit leg, either outbound or inbound, total round-trip times remain comparable to and one long transit leg, that requires close those of the minimum-energy, long-stay passage by the Sun (0.7 AU or less). A missions; but the one-way transits are significant characteristic of this class of substantially reduced, in some cases to less trajectory is that the vast majority of the than 100 days, and the Mars stay-times are round-trip time, typically over 90 percent, is increased modestly to as much as 600 days. spent in interplanetary space. The second The round-trip energy requirements of this mission class consists of long-duration Mars class, referred to as a “fast-transit” mission, stay-times (as much as 500 days) and long are similar to the short-stay missions even total round-trip times (approximately 900 though the trajectories are radically different. days). This mission type is often referred to as The profile for a typical fast-transit mission is shown in Figure 3-4.

3-37 MISSION TIMES possible about how humans react in this OUTBOUND 150 days environment. Verifying the ability of people Earth Launch STAY 619 days 2/1/2014 RETURN 110 days Depart Mars to inhabit Mars requires more than a brief 3/11/2016 TOTAL MISSION 879 days stay of 30 days at the planet. In addition, the

γ low return on investment associated with a 30-day stay at Mars (of which significantly

Nominal Departure Earth Return less than 30 days would actually be 6/29/2016 3/11/2016 productively spent on the Mars surface due to

Arrive Mars the crew adaptation to the Mars gravity, crew 7/1/2014 preparations for Mars departure, etc.) was considered unacceptable. Following the Figure 3-4 Fast-transit mission profile. August 1992 Workshop (Duke, et al., 1992), it was decided that the “Plant the Flag” mission 3.5.2 Trajectory Selection Factors objective was not a tenable rationale to support the substantial investment involved. Three factors make the selection of the Consequently, a long-stay trajectory option trajectory class critical to the Reference was considered to be best able to satisfy the Mission. First, the selection must be consistent greatest number of mission goals and with achieving the Mars exploration goals objectives. and objectives. Second, the selection must be consistent with the risk philosophy of the 3.5.2.2 Satisfying Reference Mission Risk Reference Mission. And third, for Strategy programmatic reasons, the trajectory class selection must provide the flexibility to The applicability of each of the conduct missions in all opportunities within previously discussed mission types to the the 15-year Earth-Mars trajectory cycle and to human exploration of Mars has been the conduct missions supporting the evolution of subject of much debate. The general opinion Mars exploration objectives and is that the initial flights should be short-stay implementation strategies. missions performed as fast as possible (so- called “sprint” missions) to minimize crew 3.5.2.1 Satisfying Reference Mission Goals exposure to the zero-g and space radiation and Objectives environment, to ease requirements on system reliability, and to enhance the probability of The goals and objectives of the Reference mission success. However, when considering Mission focus on allowing human crews to “fast” Mars missions, it is important to spend the greatest amount of time on the specify whether one is referring to a fast surface of Mars for the investment made to round-trip or a fast-transit mission. Past transport them there and to learn as much as

3-38 analyses have shown that decreasing round- exceeding long-term cancer risk by more than trip mission times for the short-stay missions 3% above the natural cancer death probability does not equate to fast-transit times (that is, (which is approximately 20% lifetime risk for less exposure to the zero-g and space the US population as a whole). At present, radiation environment) as compared to the the information required to calculate long-stay missions. Indeed, fast-transit times acceptable risk from radiation exposure are available only for the long-stay missions. during a Mars mission, especially for the This point becomes clear when looking at GCR, is not available. Although doses (the Figure 3-5 which graphically displays the average physical energy deposition by transit times as a function of the total round- incident particles) can be calculated, the trip mission duration. Although the short-stay conversion of this information into a mission has approximately half the total predicted radiation risk cannot be done duration of either of the long-stay missions, accurately. The National Research Council over 90 percent of the time is spent in transit, recently issued a report estimating the compared to 30 percent for the fast-transit uncertainty in risk predictions for GCR can be mission. as much as 4-15 times greater than the actual risk, or as much as 4-15 times smaller. The interplanetary ionizing radiation of concern to mission planners consists of two Current knowledge does allow for some components: galactic cosmic radiation (GCR) qualitative conclusions to be drawn. Radia- and solar particle events. NASA policy tion risk on the Mars surface, where the GCR establishes that exposure of crews to radiation fluence is attenuated by 75 percent due to the in space shall not result in heath effects Mars atmosphere and the planet itself, is exceeding acceptable risk levels. At present, likely to involve less risk than a comparable acceptable risk levels are based on not length of exposure in interplanetary space. If the difference in radiation effectiveness Long-Stay (Minimum between the interior of a shielded spacecraft Energy) and a habitat on the surface of Mars is not Long-Stay (Fast-Transit) considered, the GCR fluence to which crews are exposed during a 500 plus day transit to Short-Stay Mars is equivalent to approximately 125 days

0 100 200 300 400 500 600 700 800 900 1000 of Mars surface exposure. A significant

Mission Duration, Days reduction in transit time, to 100 days for the

Outbound Transit Time at Destination Return Transit one-way transit, would result in a radiation exposure comparable to the short-stay mission. Thus, the risk to crews on fast- Figure 3-5 Round-trip mission transit missions may be even less than the risk comparisons.

3-39 to crews on short-stay missions, not only long surface stays associated with the because of minimized exposure to GCR but minimum-energy, fast-transit missions. also reduced probability of exposure to solar Several potential solutions to the particle events in interplanetary space. physiological problems associated with zero-g A similar analysis of mission classes is transits to and from Mars may exist: involved in considering the crew’s exposure countermeasures (exercise, body fluid to the zero-g environment during transits to management, lower body negative pressure), and from Mars. Significant physiological artificial-g spacecraft, and reduced transit changes occur when zero-g time begins to be times. measured in weeks or months. (Bone The usefulness of countermeasures to decalcification, immune and cardiovascular reduce some of the zero-g effects is still system degradation, and muscular atrophy unknown. Russian long-duration crews have are a few of the more unpleasant effects.) experienced physiological degradation even Research on the effects of long-term zero-g on when rigorous exercise regimens have been the human body is in an elementary stage. At followed. However, most of these effects seem the time of the writing of this report, the to be quickly ameliorated upon return to a longest continuous stay in space by a U.S. one-g environment, at least when immediate astronaut is the 181 days of Shannon Lucid medical aid is available. (aboard the Russian MIR Space Station); the longest stay by a Russian cosmonaut is 366 Rotating the Mars transfer vehicle (MTV) days. In none of the cases were crews exposed and ERV is a method of providing an to zero-g/partial-g/zero-g sequences similar artificial-g environment for the crew and is to that projected for Mars missions. Current most often associated with low-performance data indicates that recovery in a one-g propulsion systems, or the short-stay class of environment can be fairly rapid (a few days), trajectories (since both require long transit but development of full productivity could times). Studies have indicated that the MTV require significantly more time. Upon arrival design mass penalties are on the order of 5 on the martian surface, the crew will need to percent to 20 percent if artificial g is spend some currently unknown, but probably incorporated. Depending on the specific short, time re-adapting to a partial-g field. configuration, there may also be operational This may be of concern for the short-stay complications associated with artificial-g missions where a substantial portion of the spacecraft including EVA, maintenance, and surface stay-time could be consumed by crew the spin-up/spin-down required for adaptation to martian gravity. Conversely, midcourse maneuvering and rendezvous and ample time will be available for the crew to docking. regain stamina and productivity during the

3-40

Time Outbound may prove sufficient to ameliorate the (Days) Inbound physiological effects of the relatively short 600 Total outbound transit. 500

400 Maximum Soviet 3.5.2.3 Satisfying Reference Mission Program Experience 300 (366 Days) Flexibility

200 Finally, the selection of trajectory type Maximum US 100 Experience (84 Days) depends on its allowance for flexibility to 0 Minimum Energy * Fast-transit * Short Stay ** respond to mission opportunities and * Zero-g transits separated by long surface stay (450-600 days) ** Zero-g transits separated by short surface stay (30-90 days) implementation strategies. The higher energy, short-stay missions significantly vary in both propulsive requirements and round-trip flight Figure 3-6 Microgravity times across the 15-year Earth-Mars trajectory comparisons for various mission cycle. Additionally, these missions generally classes. require the use of a Venus swingby maneuver to keep propulsive requirements within reason. However, these swingbys are not Figure 3-6 illustrates some example always available on the return transit leg and transit times for minimum-energy, fast-transit, must be substituted in the outbound transit and short-stay missions. Note that all one- leg. Because the transit leg containing the way transits are within the Russian zero-g Venus swingby is the longer of the two, the database. crew will spend up to 360 days on the trip to However, the surface stay-times for Mars, with any associated physiological short-stay missions are typically 1 to 3 degradation occurring at the beginning of the months. It is unknown whether such a short mission—that is, prior to the crew’s arrival at time spent in a 0.38-g field will counteract 5 Mars. These variations in the trajectory months of outbound zero-g exposure. In energy requirements can significantly impact contrast, the one-way trip times of the configuration of the Earth-Mars representative fast-transit missions are nearly transportation elements for different Earth- within the current U.S. zero-g database, Mars opportunities. Programmatically, such a which will certainly be augmented by normal result is unattractive. In contrast, the International Space Station operations prior to minimum-energy, long-stay missions exhibit executing human interplanetary missions. very little variation over the 15-year cycle, Also note that the fast-transit mission’s zero-g while the fast-transit long-stay missions transfer legs are separated by a substantial reflect only moderate variations across the period of time in the martian gravitational same 15-year cycle. In addition, neither field. This long period on the surface of Mars

3-41 mission requires a Venus swingby or travel propulsive capability improvements or would inside the Earth’s orbit around the Sun. necessitate much larger interplanetary spacecraft launched into LEO for the human 3.5.3 Mission Design Strategy missions, thereby requiring assembly and Keeping the Reference Mission goals and docking in LEO and higher ETO launch rates. objectives in mind, numerous alternatives Indeed, others have demonstrated that were considered that could successfully reductions in trip times reach a point of accomplish the basic mission. Two major diminishing returns from the space transfer considerations that drove many of the vehicle design perspective (Drake, 1991). 2 2 mission design-related selections include: Thus, a C3 leaving Earth of 20 to 25 km /sec appears to be appropriate for human •Reducing the amount of propellant missions. This results in maximum Earth- needed to move mission hardware from Mars transit times of approximately 180 days one location to another (propellant mass (2009 opportunity) and minimum transit is the single largest element of all times of approximately 120 days (for the 2018 components in the Reference Mission) opportunity, the best case). Similarly, a C3 •Extending the amount of time spent by leaving Mars of ~16 km2/sec2 appears to be the crew conducting useful appropriate for human missions, resulting in investigations on the surface of Mars. similar Mars-Earth transfer times for these opportunities. (C3 is a measure of the energy The alternatives selected by the Mars required to get from Earth to Mars or vice Study Team that impact mission design versa. Specifically, C3 is the square of the strategy have been grouped into six major velocity of departure from a planet. Low C3s areas and are presented here. Other are desirable because there is a direct alternatives will be discussed in subsequent correlation between C3 and the size of the sections. transportation system.) 3.5.3.1 Trajectory Type 3.5.3.2 Split Mission Strategy The discussion presented in the previous The split mission approach has been section led to the selection of the fast-transit, adopted for the Reference Mission because it long-stay class trajectories. However, the allows mission elements to be broken into amount of reduction sought in the Earth-Mars manageable pieces rather than trying to and Mars-Earth transit times must be integrate all necessary hardware elements for balanced with other considerations. a single, massive launch. For this mission, Reductions below 180 days in the one-way “manageable” was defined to mean pieces transit times (for the 2009 opportunity, the that can be launched directly from Earth and worst case) would require either significant sent to Mars, using launch vehicles of the

3-42 Saturn V or Energia class, without used to capture into orbit about Mars, and rendezvous or assembly in LEO. A key current technology can develop an aeroshell attribute of the split mission strategy is that it with a mass that is equal to or less than the allows cargo to be sent to Mars without a propulsion system required for capture. Thus, crew, during the same launch opportunity or the strategy assumed the development of a even one or more opportunities prior to the single aeroshell that can be used for both crew’s departure. This creates a situation Mars orbit capture and descent maneuvers. where cargo can be transferred on low energy, Given the demands on a descent aeroshell of longer transit time trajectory, and only the the Mars entry and landing requirements, the crews must be sent on a high-energy, fast- additional capability to permit aerocapture is transit trajectory. By using a low energy considered modest. transfer, the same transportation system can deliver more payload to the surface of Mars at 3.5.3.4 Surface Rendezvous the expense of longer flight times. Spacing the The hardware elements launched as part launches needed to support a mission across of the split mission approach must come two launch windows allows much of the together on the surface of Mars, which will infrastructure to be pre-positioned and require both accurate landing and mobility of checked out prior to committing crews to major elements on the surface to allow them their mission. When combined with the to be connected or moved into close decision to focus all Mars surface proximity. The alternative was to link major infrastructure at a single site, this approach components either in Earth orbit or in Mars allows for an improved capability to orbit prior to entry and landing. Previous overcome uncertainties and outright failures studies (NASA, 1989) indicated that the heat encountered by the crews. Launches of shields for vehicles with the combined mass duplicate hardware elements, such as ERVs, implied by such an orbital rendezvous on subsequent missions provides either approach would be exceedingly large and backup for the earlier launches or growth of difficult to launch and assemble in orbit. capability on the surface. Precision landing has been demonstrated for the Moon (Apollo 12), and studies indicate 3.5.3.3 Aerocapture (Barton, et al., 1994) that available guidance Mars orbit capture and the majority of and control systems combined with a simple the Mars descent maneuver will be performed beacon transmitting from the surface using a single biconic aeroshell. The decision (assumed to be carried by the first element at to perform the Mars orbit capture maneuver the site) are sufficient to allow a vehicle to aerodynamically was based on the fact that an land at a designated location on Mars with aeroshell will be required to perform the Mars uncertainties measured in meters. descent maneuver no matter what method is

3-43 3.5.3.5 Use of Indigenous Resources maneuvers associated with the return: departing from the martian surface, departing The highly automated production of from Mars orbit, and capturing into Earth propellant from martian resources is another orbit. Several alternatives are associated with defining attribute of the Reference Mission. these three events, the proper selection of The hardware necessary to produce and store which can result in a significant savings in propellants using raw materials available on propellant and thus in mass that must be Mars (in this case, carbon dioxide from the launched from Earth. Three key choices atmosphere) is less massive than the affecting this portion of the mission are made propellant needed to depart the martian in the Reference Mission. First, the Earth- surface for orbit (Ash, et al., 1978). It is now return transit habitat used by the crew is left apparent that the technology for producing in Mars orbit. While the outbound habitat methane and liquid oxygen from the martian could have been used for this task, the atmosphere and some nominal hydrogen propellant needed to lift it is significant; and feedstock from Earth is not only an effective it is considered more valuable as part of a performance enhancement but also appears to growing surface infrastructure. The entire be technologically feasible within the next few ERV is composed of the TEI stage and the years. Splitting the launch of mission Earth-return transit habitat. The ERV is elements allows the propellant production delivered to Mars orbit fully fueled, and it capability to be emplaced, checked out, and loiters there for nearly 4 years before being operated prior to committing the crew to used by the crew in returning to Earth. launch from Earth. In addition to spacecraft Second, the crew is not captured into an Earth propulsion, this production capability on orbit at the completion of the mission, but Mars can provide fuel for surface descends directly to the surface much as the transportation, reactants for fuel cells, and Apollo astronauts did when returning from backup caches of consumables (water, the Moon. The Earth crew capture vehicle oxygen, and trace gases) for the life support (ECCV) has the necessary heat shield for system. All of these features allow for smaller Earth reentry. Third, the crew rides into Mars amounts of consumable material to be orbit in a dedicated ascent capsule. launched from Earth and contributes to the goal of learning how to live on Mars. 3.5.4 Mission Sequence 3.5.3.6 Mars Orbit Rendezvous and Direct Figure 3-7 illustrates the mission Entry at Earth sequence analyzed for the Reference Mission. The last element of mission design is In this sequence, three vehicles will be returning the crew to Earth. There are launched from Earth to Mars in each of four potentially three significant propulsive launch opportunities starting in 2007. The

3-44 ETO FLIGHT 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 ERV loiter ∆ Crew 1 TEI 1 ∆ ERV-1 parks in LMO ∆ Crew 1 Earth return 2 ∆ MAV-1 landing

3 ∆ Initial Habitat landing

6 Crew 1: launch ∆ ∆ Landing ∆ Crew 1 ascent ERV loiter ∆ Crew 2 TEI 4 ∆ ∆ ERV-2 parks in LMO Crew 2 Earth return

5 ∆ MAV-2 landing

9 Crew 2 launch ∆ ∆ Landing ∆ Crew 2 ascent ERV loiter ∆ Crew 3 TEI 7 ∆ ERV-3 parks in LMO ∆ Crew 3 Earth return

8 ∆ MAV 3 landing

12 Crew 3 launch ∆ ∆ Landing ∆ Ascent ERV loiter 10 ∆ ERV 4 LMO 11 ∆ MAV 4 landing

ERV: Earth Return Vehicle MAV: Mars Ascent Vehicle TEI: Trans Earth Injection LMO: Low Mars Orbit Figure 3-7 Mars Reference Mission sequence. first three launches will send infrastructure 3.5.4.1 First Mission: 2007 Opportunity elements to both Mars orbit and to the surface In the first opportunity, September 2007, for later use. Each remaining opportunity three cargo missions will be launched on analyzed for the Reference Mission will send minimum energy trajectories direct to Mars one crew and two cargo missions to Mars. (without assembly or fueling in LEO). The The cargo missions will consist of an ERV on first launch delivers a fully fueled ERV to one flight and a lander carrying a habitat and Mars orbit. The crew will rendezvous with additional supplies on the second. This this stage and return to Earth after completion sequence will gradually build up assets on the of their surface exploration in October 2011. martian surface so that at the end of the third crew’s tour of duty, the basic infrastructure The second launch delivers a vehicle to could be in place to support a permanent the Mars surface which is comprised of an presence on Mars. unfueled MAV, a propellant production

3-45 module, a nuclear power plant, liquid Table 3-3 lists the various payload items hydrogen (to be used as a reactant to produce deployed to the surface during the first the ascent vehicle propellant), and opportunity. And Figure 3-8 illustrates the approximately 40 tonnes of additional surface outpost configuration after payload to the surface. After this vehicle deployment of payloads from the first two lands on the surface in late August 2008, the cargo landers. nuclear reactor will be autonomously deployed approximately 1 kilometer from the 3.5.4.2 Second Mission: First Flight Crew, ascent vehicle, and the propellant production 2009 Opportunity facility (using hydrogen brought from Earth In the second opportunity, opening in and carbon dioxide from the Mars October 2009, two additional cargo missions atmosphere) will begin to produce the nearly and the first crew mission will be launched. 30 tonnes of oxygen and methane that will be Before either the crew or additional cargo required to launch the crew to Mars orbit in missions are launched from Earth in 2009, all October 2011. This production will be assets previously delivered to Mars are completed within approximately 1 year— checked out and the MAV launched in 2007 is several months before the first crew’s verified to be fully fueled. Should any scheduled departure from Earth in mid- element of the surface system required for November 2009. crew safety or critical for mission success not The third launch in the 2007 opportunity check out adequately, the surface systems will will deliver a second lander to the Mars be placed in standby mode and the crew surface; it will be comprised of a surface mission delayed until the systems can be habitat/laboratory, nonperishable replaced or their functions restored. Some of consumables for a safe haven, and a second the systems can be replaced using hardware nuclear power plant. It will descend to the originally intended for subsequent missions surface in early September 2008 and land near and which would have otherwise provided the first vehicle. The second nuclear power system enhancement; others may be plant will be autonomously deployed near functionally replaced by other systems. the first plant. Each plant will provide Table 3-4 lists the manifested payloads sufficient power (160 kWe) for the entire for launch in the 2009 opportunity. mature surface outpost, thereby providing The first cargo launch in October 2009 is a complete redundancy within the power duplicate of the first launch from the 2007 function. The outpost laboratory will include opportunity, delivering a fully fueled Earth- tools, spare parts, and teleoperated rovers to return stage to Mars orbit. The second cargo support scientific exploration and will launch similarly mirrors the second launch of provide geological and biological analyses. the 2007 opportunity, delivering a second

3-46 Table 3-3 General Launch Manifest: 2007 Launch Opportunity

Flight 1: Cargo Flight 2: Cargo Flight 3: Cargo Surface Payload • None • Ascent Capsule • Surface Habitat/Laboratory • Empty Ascent Stage • Nonperishable

• LOX/CH4 Production Consumables Plant • Power Supply (nuclear-

• LH2 Propellant Seed 160 kW) • Power Supply (nuclear- • Utility Truck 160 kW) • Spares • Utility Truck • Teleoperable Science • Pressurized Rover Rover • Additional Payload

Mars Orbit Payload • Earth-Return Vehicle • None • None

• Fueled (LOX/CH4) TEI Stage • Transit Habitat • Earth-Return Capsule

Space Transportation Vehicles • NTR Transfer Stage • NTR Transfer Stage • NTR Transfer Stage

• LOX/CH4 TEI Stage • LOX/CH4 Descent • LOX/CH4 Descent w/Mars Aerobrake Stage w/Mars Stage w/Mars Aerobrake Aerobrake

TEI: Trans Earth Injection LOX: liquid oxygen LH2: liquid hydrogen NTR: Nuclear Thermal Rocket CH4: methane unfueled ascent stage and propellant plenty of time to be available for the crew’s production module. These systems provide departure from Mars in October 2011. If the backup or extensions of the previously MAV and ERV delivered in 2007 operate as deployed capabilities. For example, the expected, then the systems delivered in 2009 second MAV and second ERV provide the will support the second crew of six that will 2009 crew with two redundant means for each launch to Mars early in 2012. leg of the return trip. If, for some reason, The first crew of six will depart for Mars either the first ascent stage or the first ERV in mid-November 2009. They leave Earth become inoperable after the first crew departs after the two cargo missions launched in Earth in 2009, the crew can use the systems October 2009, but because they are sent on a launched in 2009 instead. They will arrive in fast transfer trajectory of only 180 days, they

3-47 (unpressurized) MAV: Mars Ascent Vehicle TROV: teleoperated rover ROV:LSS: rover pressurized ISRU: life support system utilization in-situ resource PVA: photo-voltaic array Figure 3-8 Mars surface landers. first two cargo outpost after deployment of payloads from

3-48 Table 3-4 General Launch Manifest: 2009 Launch Opportunity

Flight 4: Cargo Flight 5: Cargo Flight 6: First Crew Surface Payload • None • Ascent Capsule • Crew • Empty Ascent Stage • Surface Habitat

• LOX/CH4 Production • Consumables Plant • Spares

• LH2 Propellant Seed • EVA Equipment • Bioregenerative Life • Science Equipment Support Outfitting Equipment • Science: 1 km drill • Science Equipment • Additional Payload /Spares

Mars Orbit Payload • Earth-Return Vehicle • None • None

• Fueled (LOX/CH4) TEI Stage • Transit Habitat • Earth-Return Capsule

Space Transportation Vehicles • NTR Transfer Stage • NTR Transfer Stage • NTR Transfer Stage

• LOX/CH4 TEI Stage • LOX/CH4 Descent • LOX/CH4 Descent w/Mars Aerobrake Stage w/Mars Stage w/Mars Aerobrake Aerobrake

TEI: Trans Earth Injection LOX: liquid oxygen LH2: liquid hydrogen NTR: Nuclear Thermal Rocket CH4: methane will arrive in Mars orbit approximately 2 Additional time will be available during the months prior to the cargo missions. Once the outbound leg to conduct experiments and TMI burn has been completed, the crew must continue a dialog with Earth-bound science reach the surface of Mars. During the and exploration teams who may revise or outbound portion of this mission, the crew refine the initial set of surface activities will use their time to monitor and maintain conducted by this crew. The crew carries with systems on board the transit spacecraft, them sufficient provisions for the entire 600- monitor and maintain their own physical day surface stay in the unlikely event that condition, and train for those activities they are unable to rendezvous on the surface associated with capture and landing at Mars. with the assets previously deployed.

3-49 The crew will land on Mars in a surface investigations and participants in the habitat almost identical to the habitat/ exploration of Mars. laboratory previously deployed to the Mars Prior to the arrival of the first human surface. The transit habitat sits atop a descent crew, teleoperated rovers (TROV) may be stage identical to those used in the 2007 delivered to the surface. When the crew opportunity. After capturing into a highly arrives, these rovers will be available for elliptic Mars orbit (250 by 33793 km), the crew teleoperation by the crew. It is also possible descends in the transit habitat to rendezvous for the rovers to be operated in a supervised on the surface with the other elements of the mode from Earth. If used in this mode, the surface outpost. There is no required TROVs may be designed to provide global rendezvous in Mars orbit prior to the crew access and may be able to return samples to descent. This is consistent with the risk the outpost from hundreds of kilometers philosophy assumed for the Reference distance from the site if they are deployed Mission. with the first set of cargo missions launched Figure 3-9 illustrates the surface outpost more than 2 years before the crew arrives. configuration at the end of the first crew's stay. As experience grows, the range of human Surface exploration activity will consist exploration will grow from the local to the of diverse observations by robotic vehicles regional. Regional expeditions lasting and human explorers, the collection of perhaps 2 weeks, using mobile facilities, may samples and their examination in the outpost be conducted at intervals of a few months. laboratory, and experiments designed to Between these explorations, analysis in the gauge the ability of humans to inhabit Mars. laboratory will continue. Figure 3-10 (Cohen, Table 3-5 lists a representative set of science 1993) provides a possible surface mission and exploration equipment that will be timeline for the first 600-day mission. delivered as part of the cargo on Flight 5. The deployment of a bioregenerative life These payloads are simply examples; the support capability will be an early activity selection of specific experimental capability following crew landing. This bioregenerative will depend on the requirements of martian system is not required to maintain the health science at the time that the missions are and vitality of the crew; however, it will defined in detail. There is also a category improve the robustness of the life support listed for “discretionary principal investigator system and is important to the early (PI) science.” This category of experimental objectives of the outpost. equipment will be allocated to investigators who have competed through a proposal and The first crew will stay at the outpost peer review process and are selected for one from 16 to 18 months. Part of their duties will of these flights. This allows a wider range of be to prepare the outpost site for the receipt of

3-50 (unpressurized) MAV: Mars Ascent Vehicle TROV: teleoperated rover ROV:LSS: rover pressurized ISRU: life support system utilization in-situ resource PVA: photo-voltaic array Figure 3-9 Mars surface stay. outpost at the end of first flight crew's

3-51 Table 3-5 Surface Science Payload for First Flight Crew Payload Description Payload Mass (kg) Field Geology Package: geologic hand tools, cameras, 335 sample containers, documentation tools Geoscience lab instruments: microscopes, 125 geochemical analysis equipment, camera Exobiology laboratory: enclosures, microscopes, 50 culture media Biomedical/bioscience lab 500 Traverse geophysics instruments 400 Geophysics/meteorology instruments (8 sets) 200 10-meter drill 260 Meteorology balloons 200 Discretionary PI science 300 Total 2370 additional elements launched on subsequent typically has been in an untended mode for mission opportunities. Systems associated nearly 4 years prior to the crew’s arrival. with the ascent vehicle, although monitored During the return portion of the mission, during the entire stay on the surface, will be the crew will again spend a significant checked and, if necessary, tested in detail to portion of their time monitoring and ensure that they will operate satisfactorily. maintaining systems on board the transit The surface crew will also spend increasing spacecraft, monitoring and maintaining their amounts of time rehearsing the launch and physical condition, and training for the rendezvous phase of the Mars departure to activities associated with Earth return. As sharpen necessary skills that have not been mentioned previously, the second crew will used in over 2 years. Because the first crew be in transit to Mars during a portion of the will have to depart before the second crew first crew’s return to Earth. This implies that a arrives, surface systems will have to be in debriefing of the first crew, to gain insight standby mode for approximately 10 months. from lessons learned and suggestions for After their stay on Mars, the crew uses future surface activities, will begin during this one of the previously landed ascent vehicles return phase. This debriefing will be relayed to return to orbit, rendezvous with the ERV, to the outbound crew so that they can and return to Earth. Like the outbound transit participate in the interaction with the leg, the crew rides in a habitat on the inbound returning crew and modify their plans to take transit leg. This habitat is part of the Earth- advantage of the first crew’s experience. return stage deployed in a previous On landing, the first crew and their opportunity by one of the cargo flights and returned samples will be placed in quarantine

3-52 Mars Surface Mission Time Allocation

(Total Time = 8 crew X 24 hr/day X 600 days = 115,200 hr)

8 crew X 24 hr day = 200)

Personal Hr/Over 14 hr head Production (total 67,200 hr) 7 hr 3 hr (33,600 hr total) (14,400 hr)

Site Prep, Construction 90 days Verification Week Off 7 days Local Excursions

Analysis 100 days Distant Excursion 10 days Analysis 40 days Week Off 7 days Charge Fuel Cells Distant Excursion Check Vehicle Analysis Load Vehicle Plan Excursion Distant Excursion Drive Vehicle Analysis Navigate Don Suits (X 20) Week Off Pre-breathe (X 20) Distant Excursion Egress (X 20) 100 days Unload Equip Recreation, Exercise, Relaxation: 1 hr One Day Off Per Week: 3 hr (per day) Eating, Meal Prep, Clean-up: 1 hr Analysis Set up Drill (X 10) Sleep, Sleep Prep, Dress, Undress: 8 hr Operate Drill Distant Excursion

600 day (or 20 months, or 86 weeks) Collect Samples Hygiene, Cleaning, Personal Communication: 1 hr Analysis In Situ Analysis Take Photos Flare Retreat 15 days Communicate Week Off 7 days Disassemble Equip System Monitoring, Inspection, Calibration, Maintenance, Repair: 1 hr Load Vehicle Distant Excursion Ingress (X 20)

General Planning, Reporting, Documentation, Earth Communication: 1 hr Analysis Clean Suit (X 20) Stow Suit, Equip Distant Excursion Group Socialization, Meetings, Life Sciences Subject, Health Monitoring, Care: 1 hr 100 days Inspect Vehicle Analysis Secure for night (Sleep, eat, cleanup Week Off 7 days hygiene, etc. Sys Shutdown covered) Departure Prep 60 days

3 Crew X 7 hr X 10 Day = 210 hrs total

Figure 3-10 Possible surface mission time line.

3-53 in accordance with the protocols in effect at Figure 3-11 illustrates the surface outpost the time. The crew’s re-adaptation to a 1-g configuration at the end of the second crew's environment will be monitored in detail to stay. learn more about how the human body As before, the second crew will continue adapts to the varying gravity conditions and with the general type of activities conducted to better prepare for the return of subsequent by the first crew: diverse observations by crews. robotic vehicles and human explorers, collection of samples and their examination in 3.5.4.3 Third Mission: Second Flight Crew, the outpost laboratory, and experiments 2011 Opportunity designed to gauge the ability of humans to In the third opportunity opening in inhabit Mars. Specific crew activities will December 2011, two additional cargo build on the lessons learned and questions missions and the second crew mission will be generated by the first crew. Table 3-7 lists a launched. As in the second opportunity, all representative set of science and exploration assets previously delivered to Mars are equipment that will be delivered as part of checked out and the MAV is verified to be the cargo on Flight 8. Note in particular that fully fueled. Any non-mission-critical this manifest contains a drill designed to maintenance items identified by the first crew reach depths of 1 kilometer. (The deep drilling or items noted prior to the departure of operation must be consistent with planetary Flights 7 through 9 are added to the spares protection protocols.) This tool will be used to manifest and delivered with other surface gather subsurface core samples that will help equipment. Table 3-6 lists the manifested reconstruct the geologic history of Mars, and payloads for launch in the 2011 opportunity. to try to locate subsurface deposits of water in Prior to the arrival of the second crew, the either liquid or solid form. Such a discovery ISRU plants are producing not only the will substantially enhance the habitability propellants needed for the ascent vehicle, but prospects for future crews by possibly also water, oxygen, and buffer gases to serve upgrading propulsion systems to the use of as an emergency cache for the life support hydrogen and oxygen and expanding system. Teleoperated rovers are deployed on agricultural activities. extended traverses, perhaps to distances of The second crew will repeat the activities more than 100 kilometers, to take measure- of the first crew in preparing themselves, the ments, gather samples, and reconnoiter sites ascent vehicle, and the surface habitat for a for the human crew to investigate in more departure from Mars during December 2013. detail. The third crew will already be in transit to

3-54 Table 3-6 General Launch Manifest: 2011 Launch Opportunity

Flight 7: Cargo Flight 8: Cargo Flight 9: Second Crew Surface Payload • None • Ascent Capsule • Crew • Empty Ascent Stage • Surface Habitat

• LOX/CH4 Production • Consumables Plant • Spares

• LH2 Propellant Seed • EVA Equipment • Pressurized Rover • Science Equipment • Science Equipment • Additional Payload/ Spares

Mars Orbit Payload • Earth-Return Vehicle • None • None

• Fueled (LOX/CH4) TEI Stage • Transit Habitat • Earth-Return Capsule

Space Transportation Vehicles • NTR Transfer Stage • NTR Transfer Stage • NTR Transfer Stage

• LOX/CH4 TEI Stage • LOX/CH4 Descent • LOX/CH4 Descent w/Mars Aerobrake Stage w/Mars Aerobrake Stage w/Mars Aerobrake

TEI: Trans Earth Injection LOX: liquid oxygen LH2: liquid hydrogen NTR: Nuclear Thermal Rocket CH4: methane

Mars, again necessitating a debriefing of the the third crew mission will be launched. As in second crew, with participation by the third the second and third opportunities, all assets crew, during the return to Earth. Once on previously delivered to Mars are checked out Earth, the second crew will likely benefit from and the MAV is verified to be fully fueled. observations of the first crew, particularly in Any non-mission-critical maintenance items the areas of modifications to the re-adaptation identified by the first two crews or items regime and quarantine protocols. noted prior to the departure of Flights 10 through 12 are added to the spares manifest 3.5.4.4 Fourth Mission: Third Flight Crew, and delivered with other surface equipment. 2014 Opportunity Table 3-8 lists the manifested payloads for In the fourth opportunity opening in launch in the 2014 opportunity. As listed, the March 2014, the final two cargo missions and manifests do not use the full cargo-carrying

3-55 (unpressurized) MAV: Mars Ascent Vehicle TROV: teleoperated rover ROV:LSS: rover pressurized ISRU: life support system utilization in-situ resource PVA: photo-voltaic array Figure 3-11 Mars surfaceFigure outpost at the end of second flight crew's stay.

3-56 Table 3-7 Surface Science Payload for Second Flight Crew Payload Description Payload Mass (kg) Field Geology Package: geologic hand tools, cameras, 335 sample containers, documentation tools Geoscience lab instruments: microscopes, 125 geochemical analysis equipment, camera Exobiology laboratory: enclosures, microscopes, 50 culture media Biomedical laboratory 500 Plant and animal lab 500 Traverse geophysics instruments 400 Geophysics/meteorology instruments (8 sets) 200 1 kilometer drill 20,000 10-meter drill 260 Meteorology balloons 200 Discretionary PI science 600 Total 23,000 capacity of the landers. The experience gained capabilities available at this stage, the surface by the first two crews will dictate any outpost will be able to support larger crews additional equipment that can be used to for longer periods of time. The potential level either upgrade existing equipment or add of self-sufficiency on Mars should also be new equipment to enhance the capabilities of evident by this time, and a decision can be this outpost. made regarding any further use or expansion of the outpost. Prior to the arrival of the third crew, the ISRU plants are again producing not only the As before, the third crew will continue propellants needed for the ascent vehicle, but with the general type of activities conducted also water, oxygen, and buffer gases to serve by the first and second crews: diverse as an emergency cache for the life support observations by robotic vehicles and human system. Teleoperated rovers are again explorers, collection of samples and their deployed on extended traverses to take examination in the outpost laboratory, and measurements, gather samples, and experiments designed to gauge the ability of reconnoiter sites for the third crew to humans to inhabit Mars. Specific crew investigate in greater detail. activities will build on the lessons learned and questions generated by the first two Figure 3-12 illustrates the surface outpost crews and should be focused on providing configuration at the end of the third crew's information needed to determine the future stay. This represents the complete outpost status of the outpost. Table 3-9 lists a configuration as envisioned by the Mars representative set of science and exploration Study Team. With the facilities and

3-57 (unpressurized) MAV: Mars Ascent Vehicle TROV: teleoperated rover ROV:LSS: rover pressurized ISRU: life support system utilization in-situ resource PVA: photo-voltaic array Nuclear Power Plant Nuclear Power Plant Figure 3-12 Mars surfaceFigure stay. flight crew's outpost at the end of third

3-58 Table 3-8 General Launch Manifest: 2014 Launch Opportunity

Flight 10: Cargo Flight 11: Cargo Flight 12: Third Crew

Surface Payload • None • Ascent Capsule • Crew • Empty Ascent Stage • Surface Habitat

• LOX/CH4 Production • Consumables Plant • Spares

• LH2 Propellant Seed • EVA Equipment • Science Equipment • Science Equipment • Additional Payload/ Spares

Mars Orbit Payload • Earth-Return Vehicle • None • None

• Fueled (LOX/CH4) TEI Stage • Transit Habitat • Earth-Return Capsule

Space Transportation Vehicles • NTR Transfer Stage • NTR Transfer Stage • NTR Transfer Stage

• LOX/CH4 TEI Stage • LOX/CH4 Descent • LOX/CH4 Descent w/Mars Aerobrake Stage w/Mars Aerobrake Stage w/Mars Aerobrake

TEI: Trans Earth Injection LOX: liquid oxygen LH2: liquid hydrogen NTR: Nuclear Thermal Rocket CH4: methane

equipment that will be delivered as part of missions use assumed hardware systems and the cargo on Flight 11. mission design principles to place the flight crews in the martian environment for the As with the first two crews, the third longest period of time at a satisfactory level of crew will repeat those activities necessary to risk. The major distinguishing characteristics prepare themselves, the ascent vehicle, and of the Reference Mission, compared to the surface habitat for a departure from Mars previous concepts, include: during January 2016. •No extended LEO operations, assembly, 3.5.4.5 Mission Summary or fueling

This section has illustrated a feasible •No rendezvous in Mars orbit prior to sequence of missions that can satisfy the landing Reference Mission goals and objectives. These

3-59 Table 3-9 Surface Science Payload for Third Flight Crew

Payload Description Payload Mass (kg) Field Geology Package: geologic hand tools, cameras, 335 sample containers, documentation tools Geoscience lab instruments: microscopes, 125 geochemical analysis equipment, camera Exobiology laboratory: enclosures, microscopes, 50 culture media Plant and animal lab 500 Traverse geophysics instruments 400 Geophysics/meteorology instruments (8 sets) 200 Advanced Meteorology Laboratory 1000 10-meter drill 260 Meteorology balloons 200 Discretionary PI science 1000 Total 4070

•Short transit times to and from Mars (180 The characteristics of the hardware days or less) and long surface stay-times systems used in these missions are more (500 to 600 days) for the first and all completely discussed in the following subsequent crews exploring Mars sections.

•A heavy-lift launch vehicle (HLLV), 3.6 Systems capable of transporting either crew or cargo direct to Mars, and capable of The following sections discuss the delivering all needed payload with a characteristics and performance capabilities total of four launches for the first human of the various hardware elements needed for mission and three launches of cargo and the Reference Mission. The hardware crew for each subsequent opportunity elements include a launch vehicle large enough to place cargo bound for Mars into a •Exploitation of indigenous resources suitable Earth parking orbit, the from the beginning of the program, with interplanetary transportation elements important performance benefits and necessary to move crew and equipment from reduction of mission risk Earth to Mars and back, and the systems •Availability of abort-to-Mars-surface needed to sustain the crew and perform the strategies, based on the robustness of the proposed exploration activities on the martian Mars surface capabilities and the cost of surface. Each section describes the principal trajectory aborts characteristics of the hardware system as developed by the Mars Study Team.

3-60 3.6.1 Operational Design common hardware and software where Considerations applicable. System commonality in power Several operational factors related to sources, interfaces, payload locker sizes, etc., utilization, training, and repair influence the among all vehicles will ease nominal design of hardware and software systems for operational activities such as replacements, all vehicles. Early incorporation of these reconfigurations, and hardware transfers. factors into the vehicle design process will Commonality will also help maintain enhance utility and functionality of the corporate knowledge bases and simplify crew systems, prevent costly workarounds late in operations and repair procedures as the development cycle, and maximize overall experience with one system can be applied to mission success. many. The cost savings associated with the use of common hardware and software This section discusses some of the design elements are obvious, and may be increased considerations identified as important in the by using as much off-the-shelf hardware as eventual detailed design and construction of possible. This, too, helps with familiarity as systems used for the Reference Mission. crews and technicians may have previous While the system descriptions in the sections experience with similar systems. Repair that follow may not reach a level of detail that operations will also be simplified by requiring reflects the specific topics mentioned here, the a smaller set of standard tools for use by the design considerations should be considered crew during mission execution. as guiding principles that should be used as more detailed studies are performed. The need for training facilities will have a significant impact on vehicle design. Due to A primary operational consideration in the extended duration of the mission, training system development is the subsequent ease facilities will be required on board crew with which users, specifically crew members, vehicles during various phases of the mission. can become familiar with the system prior to Trainers on Earth will need to match trainers the mission. The more familiar crew members on vehicles which in turn will need to match are with vehicle hardware and software, the actual system performance. The requirement less time will be spent on systems operations for crew training facilities during various and the more time will be available for mission phases will place additional science and exploration activities. By the same hardware and software design constraints on token, the more familiar technicians are with the vehicles. Incorporation of training the systems, the easier and less costly facilities into appropriate vehicles is an production, maintenance, and repair will be important operational factor influencing the during the development process. To facilitate design process. this, all vehicles and systems need to use

3-61 For both crew safety and operational discretionary system failures can require simplicity, system designs will require some some crew response to enhance mission level of automatic fault detection for all life- objectives. A balance between the cost of critical, mission-critical, and mission- automation and crew time and training for discretionary elements. For those elements such activities will be needed. In general, pertaining to crew safety and mission-critical maximizing crew science time and objectives, auto-fault detection and correction minimizing crew system maintenance and should be incorporated into the design. Crew operations throughout the mission will action should not be required for life-critical improve overall mission success. systems failures; backup system activation should be automatic. Mission-critical system 3.6.2 Launch Vehicles failures should be as automated as possible, The scale of the ETO launch capability is leaving only the most complex tasks (such as fundamentally determined by the mass of the complete hardware replacement or repair) to payload that will be landed on the martian the crew. In addition, many of the routine, yet surface. The nominal design mass for important, system operations should be individual packages to be landed on Mars in automated to the greatest extent possible. For the Reference Mission is 50 tonnes for a crew example, an often overlooked aspect of habitat (sized for six people) which must be operations is consumables tracking and transferred on a high-energy, fast-transit orbit. forecasting for all life-critical and mission- This in turn scaled the required mass in LEO critical systems. Crew time is better spent on to about 240 tonnes. science activities than on tracking and forecasting consumables such as propellant, A number of different technologies could water, and breathable air. Many of these be used to construct a single launch vehicle functions are currently done for Space Shuttle capable of placing 240 tonnes into a 220- crews by flight controllers on the ground. Due nautical mile circular orbit. These launch to the long delay time in communications vehicle concepts used various combinations during the Reference Mission, maintenance of of past, present, and future U.S. expendable this function by ground personnel is launch vehicle technology and existing launch impractical. Periodic verification of vehicle technology from Russia and Ukraine. consumables tracking activities by ground Table 3-10 summarizes some of the key personnel can validate the crew activities; parameters for a representative set of the however, means by which the crew can vehicle options examined (Huber, 1993). Each independently monitor and forecast option is covered in more detail in the propulsive and nonpropulsive consumables following paragraphs. while not expending significant resources is a Option 1 (Figure 3-13) illustrates the necessity. Where cost effective, mission- capabilities possible through the use of

3-62 Energia and Zenit launch vehicle technology combination of largely existing components combined with STS technology. All of the does not meet the desired payload launch engines used for this option are existing types mass. that have flown numerous times. The core Option 2 (Figure 3-14) illustrates what is stage is assumed to be a modification of the possible if a large launch vehicle makes existing Energia stage. The modification extensive use of existing STS and Russian involves changing the vehicle from one that technology. The first stage core and upper uses a side-mounted payload container to an stage use the SSME, and the propellant tank in-line configuration with strap-on boosters structure is based on the STS external tank. surrounding the core. The upper stage is a Strap-on boosters for this vehicle use the new development using STS external tank Russian RD-170 engine and a newly designed technology combined with a single SSME. propellant tank structure. Note that this The shroud is entirely new and would be combination also does not meet the desired sized for the largest of the Reference Mission payload launch mass. payloads. Note, however, that this

Table 3-10 Launch Vehicle Concepts for the Reference Mission

Option Payload Mass (tonnes) to 220 Key Technology Assumptions n.mi. Circular Orbit

1 179 Modified Energia core with eight Zenit- type strap-on boosters. New upper stage using a single Space Shuttle Main Engine (SSME). 2 209 New core stage based on Space Transportation System (STS) external tank and SSMEs. Seven new strap-on boosters each use a single RD-170 engine. New upper stage using a single SSME. 3 226 New core stage based on STS external tank and four of the new Space Transportation Main Engines. Four strap-on boosters each with a derivative of the F-1 engine used on the first stage of the Saturn V. New upper stage using a single SSME. 4 289 New vehicle using technology derived from the Saturn V launch vehicle. Boosters and first stage use a derivative of the F-1 engine, and the second stage uses a derivative of the J-2 engine.

3-63 Figure 3-13 Mars Energia-derived HLLV with eight Zenit-type boosters.

3-64 Figure 3-14 STS External Tank-derived HLLV with seven LOX/RP boosters.

3-65 Option 3 (Figure 3-15) uses new and old Because a 240-ton-class launch vehicle as well as existing technology to create a would be such a development cost issue, vehicle that can deliver a payload that is consideration was given to the option of reasonably close to the desired value. The first launching several hardware elements to LEO stage core propellant tank structure is based using smaller vehicles, assembling (attaching) on the STS external tank but uses newly them in space, and then launching on the designed and as yet untested STME engines. outbound trajectory to Mars. This smaller The strap-on boosters use an updated version launch vehicle (with a 110- to 120-ton payload of the F-1 engine that powered the first stage capability) would have the advantage of more of the Saturn V in conjunction with newly modest development costs and is in the designed propellant tanks. The upper stage is envelope of capability demonstrated by the comparable to those discussed for the first unmodified U.S. Saturn V and Russian two options, using STS external tank Energia programs (Figure 3-18). However, technology and a single SSME. this smaller launch vehicle introduces several potential difficulties to the Reference Mission Option 4 (Figure 3-16) is indicative of a scenario. The most desirable implementation launch vehicle that uses technology derived using this smaller launch vehicle is to simply from the Saturn V launch vehicle. The first dock the two elements in Earth orbit and stage core is virtually identical to the first immediately depart for Mars. To avoid boiloff stage of the Saturn V launch vehicle in its losses in the departure stages (assumed to use basic size and its use of five F-1A engines. liquid hydrogen as the propellant), all Strapped to this stage are four boosters, each elements must be launched from Earth in with two F-1A engines and roughly one-third quick succession, placing a strain on existing of the propellant carried by the core stage. launch facilities and ground operations crews. The second stage uses six of the J-2 engines Assembling the Mars vehicles in orbit and that powered the second stage of the Saturn loading them with propellants just prior to V. However, this upper stage is considerably departure may alleviate the strain on launch larger than the Saturn second stage. facilities, but the best Earth orbit for Mars This last option was the largest of a missions is different for each launch family of launch vehicles derived using opportunity, so a permanent construction Saturn V launch vehicle technology. Figure and/or propellant storage facility in a single 3-17 illustrates some of the other vehicle Earth orbit introduces additional constraints. configurations examined and provides Several launch vehicle designs that could additional information on their capabilities. provide this smaller payload capability using All of these options can deliver a payload existing or near-term technology were almost as large as the stated need for 240 examined. Figure 3-19 illustrates one possible tonnes in a 220-nautical mile circular orbit.

3-66 Figure 3-15 STS External Tank-derived HLLV with four strap-on boosters, each having two F-1 engines.

3-67 Figure 3-16 Saturn V-derived Mars HLLV with F-1A/J-2S propulsion.

3-68 VAB Height Limit - 410'

400

300

200 Vehicle Height (ft.) Vehicle

100

0

2x2 F-1A Boost 2x2 F-1A Boost 2x2 F-1A Boost 2x2 F-1A Boost 2x2 F-1A Boost 5 F-1A Core 5 F-1A Core 5 F-1A Core 5 F-1A Core 5 F-1A Core 6 J-2S 2nd Stage 6 J-2S 2nd Stage 6 J-2S 2nd Stage 6 J-2S 2nd Stage 6 J-2S 2nd Stage

Shroud Diameter (Usable) 10 m 13 m 16 m 17 m 14 m

Payload to 220 nm Circular* 237 t 228 t 219 t 285 t 289 t (Kickstage performs circ.)

Figure 3-17 Saturn V-based Mars HLLV concepts.

3-69 Figure 3-18 Energia launch vehicle adapted to Mars mission profile.

3-70 320 ft

172 ft

27.6 ft D

89 ft Side View Base View

Figure 3-19 Mars mission launch vehicle with two external tank boosters and kick stage.

3-71 vehicle configuration and provides additional landed in close proximity to one another. The information on its capabilities. This particular transportation strategy adopted in the option uses the STS external tank for its Reference Mission eliminates the need for propellant storage and main structure. assembly or rendezvous in LEO of vehicle Engines for the core stage and the two strap- elements and for rendezvous of a crew on boosters were assumed to be the STME transport vehicle with a Mars lander in Mars engine that was under development at the orbit, both features of many previous mission time of this study. designs for Mars (NASA, 1989). But the Reference Mission scenario does require a A 240-ton payload-class launch vehicle is rendezvous on the surface with previously assumed for the Reference Mission. However, landed hardware elements and a rendezvous it is beyond the experience base of any in Mars orbit with the ERV as the crew leaves spacefaring nation. While such a vehicle is Mars. The transportation strategy emphasized possible, it would require a significant the use of common elements wherever development effort for the launch vehicle, possible to avoid development costs and to launch facilities, and ground processing provide operational simplicity. facilities; and its cost represents a considerable fraction of the total mission cost. 3.6.3.1 Trans-Mars Injection Stage The choice of a launch vehicle remains an unresolved issue for any Mars mission. A single TMI stage was developed for both piloted and human missions. The stage 3.6.3 Interplanetary Transportation is designed for the more energetically demanding 2009 human mission and is then The interplanetary transportation system used in the minimum energy cargo missions assembled for the Reference Mission consists to launch the maximum payload possible to of seven major systems: a TMI stage, a Mars. Because of the energetic trajectories biconic aeroshell for Mars orbit capture and used for human flights and the desire to Mars atmospheric entry, habitation systems deliver large payloads to the martian surface, for the crew (both outbound and return), a nuclear thermal propulsion was selected for descent stage for landing on the surface, an this stage not only for its performance ascent stage for crew return to Mars orbit, an advantages but also because of its advanced, ERV for departure from the Mars system, and previously demonstrated state of technology an ECCV (comparable to Apollo) for Earth development, its operational flexibility, and entry and landing. As mentioned earlier, the its inherent mission enhancements and crew Reference Mission splits the transportation of risk reduction (Borowski, et al., 1993). people and equipment into cargo missions and human missions, all of which are targeted After completion of two TMI burns to the same locale on the surface and must be (required by the selected thrust-to-weight

3-72 ratio), the stage is disposed of by allowing it ND engines. So for cost and performance to drift on a relatively stable interplanetary reasons, one ND engine and the shadow trajectory. Calculations (Stancati and Collins, shield are removed from this version of the 1992) using the Planetary Encounter TMI stage. Probability Analysis code indicate that the The TMI stage adopted for the Reference probability of a collision of a nuclear engine- Mission could be designed around any of four equipped vehicle and the Earth is quite low. reactor options studied by the Team: (1) The probabilities of a collision with Earth in Rocketdyne and Westinghouse NERVA- one million years are 3.8 percent for the derivative reactor (ND), (2) Pratt and Whitney piloted TMI stages and 12 percent for the and Babcock and Wilcox (B&W) CERMET fast cargo TMI stages. reactor, (3) Aerojet and B&W particle bed The basic TMI stage is shown in Figure reactor and (4) Russian Energopool and B&W 3-20. For piloted missions, the TMI stage uses engine concept using the “twisted ribbon” four 15,000 lb. thrust NERVA* derivative ternary carbide fuel form. Work done in (ND) engines to deliver the crew and their Russia is especially promising, with the surface habitat/descent stage onto the trans- possibility of higher Isp (approximately 950 Mars trajectory. Engines of this size are well seconds versus a 900-second demonstrated within the previous development history of capability by NERVA engines) at a thrust-to- NERVA engines (Borowski, et al., 1993). This weight ratio of about 3.0 (for a 15,000 pound version of the TMI stage incorporates a thrust engine) being a possible development shadow shield between the ND engine target. The Reference Mission adopts the assembly and the LH2 tank to protect the crew more conservative ND engine concept, with a from radiation generated by the engines that projected Isp performance of 900 seconds. will have built up during the TMI burns. For Table 3-11 lists the mass estimates for the cargo missions, this transportation system can various components of the TMI stage for deliver approximately 65 tonnes of useful piloted and cargo versions. In both versions, cargo to the surface of Mars or nearly 100 this stage is assumed to have a maximum tonnes to Mars orbit (250 I 33,793 km) on a diameter of 10 meters and an overall length of single launch from Earth. The TMI stage for 25.3 meters. cargo delivery requires only the use of three 3.6.3.2 Biconic Aeroshell

On each cargo and piloted mission, Mars From 1955 to 1973, the Nuclear Engine for Rocket orbit capture and the majority of the Mars Vehicle Application (NERVA) program designed, built, descent maneuver are performed using a and tested a total of twenty rocket reactors. The feasibility of using low molecular weight LH2 as both a single biconic aeroshell. The decision to reactor coolant and propellant was convincingly perform the Mars orbit capture maneuver demonstrated.

3-73 2007 Cargo Mission 1 2007 Cargo Mission 3 2007 Cargo Mission 2 2009 Piloted Mission 1

"Dry" Ascent Stage & Lander LOX/CH4 TEIS & Hab Hab Module & Lander Surface Hab with Crew and Lander

19.0 m 7.6 m 16.3 m 16.3 m

15.0 m

20.6 m* 86.0 t LH2 86.0 t LH2 86.0 t LH2 86.0 t LH2 (@ 100%) (@ 100%) (@ 91.9%) (@ 100%)

10 m 10 m 10 m 10 m

4.7 m

IMLEO = 216.6 t 216.6 t 204.7 t 212.1 t

* Expendable TMI Stage LH2 Tank (@ 18.2 m length) sized by 2009 Mars Piloted Mission

IMLEO Initial Mass to Low Earth Orbit TEIS Trans Earth Injection Stage

Figure 3-20 Reference Mars cargo and piloted vehicles.

3-74 Table 3-11 Mass Estimates for TMI Stage Alternatives

TMI Stage Element Piloted Version Cargo Version

ND Engines (4 for piloted, 3 for cargo) 9.8 7.4 Radiation Shield 0.9 0.0 Tankage and Structure 18.4 18.4

LH2 Propellant (maximum) 86.0 86.0 Control System Tankage and Propellant 3.1 3.0

Total (tonnes) 118.2 114.8 using an aeroshell (that is, aerocapture) was biconic aeroshells that can be used for both based on the fact that this option typically Mars orbit capture and descent maneuvers. requires less mass than an equivalent Given the demands on a descent aeroshell of propulsive capture stage (Cruz, 1979), and the Mars entry and landing requirements, the aerodynamic shielding of some sort will be additional capability to permit aerocapture is required to perform the Mars descent considered modest. maneuver no matter what method is used to The aerodynamic maneuvering and capture into Mars orbit. Previous Mars thermal protection requirements for the mission concepts employing aerocapture have aeroshells used in the Reference Mission were typically used more than one aeroshell to studied in some detail (Huber, 1993). Based deliver the crew to the surface. The use of two on the studies, it was determined that a aeroshells was driven by one or both of the biconic aeroshell with similar forward and aft following factors. First, Mars entry speeds conic sections provided sufficient may have been higher than those proposed maneuverability for the aerocapture and for the Reference Mission and therefore more entry phases of flight. Figure 3-21 illustrates maneuverability and thermal protection were two of these aeroshells, one for the Mars required for this phase of the mission. Second, ascent vehicle and the other for the surface the mission profile may have required a post- habitat. For this family of aeroshells, the nose aerocapture rendezvous in Mars orbit with section is a 25° half-angle cone ending in a another space transportation element, spherical cap. The skirt section is a 4° half- possibly delivered during the same launch angle cone with a 10-meter diameter base. opportunity or during a previous The skirt section consists of two parts: a fixed opportunity. Neither of these features is in the length aft section and a variable length center Reference Mission. Thus, the strategy section (“center” indicating its location employed was to develop a single family of between the aft skirt and the nose section).

3-75 6.0 (m) 25 % 18 (m)

14.9 (m) 7.7 (m) to Cg & Cp

4 %

8.9 (m)

Dia = 10.0 (m) Dia = 10.0 (m)

Reference Biconic: 10 (m) Dia by 15 (m) Extended Center Section Biconic length. I/D = 0.65 At 25° Angle of Attack 10 (m) Dia by 18 (m) length.

Cg = center of gravity Cp = center of pressure

Figure 3-21 Biconic aeroshell dimensions for Mars lander and surface habitat modules.

3-76 The length of the skirt center section is laboratory deployed robotically on a previous determined by the size of the payload carried mission. Although a smaller habitat might within. Table 3-12 lists the overall lengths of suffice for a crew of six during the the various aeroshells used in the Reference approximately 6 months of transit time, Mission. designing the habitat so that it can be used during transit and on the surface results in a Table 3-12 also lists an estimated mass for number of advantages to the overall mission. the various aeroshells. The Mars Study Team Duplicating habitats on the surface provides did not conduct a detailed study of the mass redundancy during the longest phase of the of the various aeroshells used. Based on mission and reduces the risk to the crew. By previous studies of aerocapture vehicles, a landing in a fully functional habitat, the crew simple scaling factor of 15 percent of the entry does not have to transfer from a “space-only” mass was used to determine the aeroshell habitat to the surface habitat immediately mass (Scott, et al., 1985). As more detail after landing, allowing them to re-adapt to a regarding the aeroshell is developed, gravity environment at their own pace. This variations in aeroshell mass will result caused approach also allows the development of only by differences in the amount of thermal one habitat system instead of two or more protection material used (some missions are unique, specialized systems (although some flown on faster trajectories and will encounter subsystems will have to be tailored for zero-g higher entry speeds with correspondingly operation). The performance of the transit higher heat loads) and in the size of the habitat may be tested by attaching a aeroshell structure. At the present level of this development unit to the International Space study, the simple scaling factor is considered Station (Figure 3-22). sufficient to estimate the aeroshell mass. Each habitation element will consist of a 3.6.3.3 Transit/Surface Habitat structural cylinder 7.5 meters in diameter and The crew is transported to Mars in a 4.6 meters long with two elliptical end caps habitat that is identical to the surface habitat/ (overall length of 7.5 meters). The internal

Table 3-12 Mass and Size Estimates for Biconic Aeroshell Family

Mass Estimate Overall Length Aeroshell Payload (tonnes) (meters)

Ascent Stage and Lander 17.3 15.0 Surface Habitat and Lander 17.3 16.3 TEI Stage and Habitat 17.3 19.0 Surface Habitat with Crew and Lander 17.3 16.3

3-77 Figure 3-22 Transit habitat attached to International Space Station. Figure 3-22 Transit

3-78 volume will be divided into two levels doubling the usable pressurized volume (to oriented so that each “floor” will be a cylinder approximately 1,000 cubic meters) available 7.5 meters in diameter and approximately 3 to the crew for the 600-day surface mission. meters in height. The primary and secondary This configuration is illustrated in Figure 3-26 structure, windows, hatches, docking with the first of the transit habitats joined to mechanisms, power distribution systems, life the previously landed surface habitat/ support, environmental control, safety laboratory. features, stowage, waste management, communications, airlock function and crew 3.6.3.4 Mars Surface Lander egress routes will be identical to the other A single common descent stage was habitation elements (the surface habitat/ developed for delivery of all hardware laboratory and the Earth-return habitat). After systems (the habitats, ascent vehicle, establishing these basic design features, there propellant production plant, and other exists an endless array of feasible internal surface cargo) to the surface of Mars. The role architecture designs. Deciding among feasible of this stage is to complete the descent-to- internal designs involves a trade of resources landing maneuver once the biconic aeroshell derived from a specific set of habitation goals. ceases to be effective and to maneuver the At this level of detail, habitation goals are surface systems into the appropriate relative somewhat subjective and open for discussion. position at the surface outpost. Figures 3-23, 3-24, and 3-25 illustrate one The descent stage consists of four internal arrangement for the transit/surface subsystems: a basic structure to which all habitat that was investigated for feasibility other elements (including payload) are and cost purposes. attached, a parachute system to assist in The Mars transit/surface habitat will slowing the stage, a propulsion system to contain the required consumables for the slow the stage prior to landing, and a surface Mars transit and surface duration of mobility system. approximately 800 days (approximately 180 The use of parachutes has been assumed days for transit and approximately 600 days to help reduce the descent vehicle’s speed on the surface) as well as all the required after the aeroshell has ceased to be effective systems for the crew during the 180-day and prior to the final propulsive maneuver transfer trip. Table 3-13 provides a breakdown (Figure 3-27). Sufficient atmosphere is present of the estimated masses for this particular for parachutes to be more effective than an habitat. equivalent mass of propellant. Once on the surface of Mars, this transit/ surface habitat will be physically connected with the previously landed surface laboratory,

3-79 Figure 3-23 The crew exercise facility component of the countermeasures system designed to inhibit crew degradation from exposure to reduced gravity environments.

Figure 3-24 EVA suit storage locations are critical in a robust crew safety system.

3-80 Figure 3-25 Conceptual Mars habitation module - wardroom design.

3-81 Table 3-13 Mars Transit/Surface Habitat Element

Subsystem Consumables Dry Mass Subsystem Mass Subtotal Subtotal (tonnes) (tonnes) (tonnes)

Physical/chemical life support 6.00 3.00 3.00 Plant growth 0.00 0.00 0.00 Crew accommodations 22.50 17.50 5.00 Health care 2.50 0.50 2.00 Structures 10.00 0.00 10.00 EVA 4.00 3.00 1.00 Electrical power distribution 0.50 0.00 0.50 Communications and information 1.50 0.00 1.50 management Thermal control 2.00 0.00 2.00 Power generation 0.00 0.00 0.00 Attitude control 0.00 0.00 0.00 Spares/growth/margin 3.50 0.00 3.50 Radiation shielding 0.00 0.00 0.00 Science 0.90 0.00 0.90 Crew 0.50 0.50 0.00

Total estimate 53.90 24.50 29.40

The propulsion system employs four previously landed pressurized rover. Figure RL10-class engines modified to burn LOX/ 3-28 illustrates one possible configuration for

CH4 to perform the post-aerocapture this lander with its mobility system. circularization burn and to perform the final The descent lander is capable of placing approximately 500 meters per second of approximately 65 tonnes of cargo on the descent velocity change prior to landing on surface. The dry mass of this lander is the surface. approximately 4.7 tonnes, and it can carry Once on the surface, the lander can move approximately 30 tonnes of propellant to be limited distances to compensate for landing used for orbital maneuvers and for the final dispersion errors and to move surface descent maneuver. elements into closer proximity. This allows, for example, the surface laboratory to be 3.6.3.5 Mars Ascent Vehicle connected to the transit/surface habitats. When the surface mission has been Mobility system power is provided by on- completed, the crew must rendezvous with board regenerative fuel cells and from the the orbiting ERV. This phase of the mission is

3-82 Figure 3-26 Habitat and surface laboratory joined on Mars surface.

3-83 Figure 3-27 Mars surface lander descending on parachutes.

3-84 Figure 3-28 Mars surface lander just prior to landing illustrating landing legs and surface mobility system.

3-85 accomplished by the MAV which consists of rendezvous has been completed and all crew, an ascent propulsion system and the crew equipment, and samples have been ascent capsule. transferred to the ERV, the MAV is jettisoned and remains in orbit around Mars. The MAV is delivered to the Mars surface atop a cargo descent stage (Figure 3-29 The MAV is depicted in Figure 3-31 illustrates the MAV inside the biconic showing basic dimensions for the vehicle. The aeroshell and deployed on the surface). The ascent propulsion system will require ascent propulsion system is delivered with its approximately 26 tonnes of propellant to propellant tanks empty. However, the same accomplish the nearly 5,600 meters per descent stage also delivers a nuclear power second of velocity change required for a source, a propellant manufacturing plant single-stage ascent to orbit and rendezvous (both discussed in later sections), and several with the previously deployed ERV. The tanks of hydrogen to be used as feedstock for structure and tankage needed for this making the required ascent propellant. This propellant and the other attached hardware approach was chosen because the mass of the elements have a mass of 2.6 tonnes, including power source, manufacturing plant, and seed the mass of the engines but not the crew hydrogen is less than the mass of the capsule. The ascent propulsion system uses propellant required by the ascent stage to two RL10-class engines modified to burn reach orbit (Stancati, et al., 1979; Jacobs, et al., LOX/CH4. These engines perform with an 1991; Zubrin, et al., 1991). Not carrying this average specific impulse of 379 seconds propellant from Earth gave the Reference throughout the MAV flight regime. Mission the flexibility to send more surface The ascent crew capsule has a maximum equipment to Mars or to use smaller launch diameter of 4 meters, a maximum height of vehicles or some combination of the two 2.5 meters, and a mass of 2.8 tonnes. This options. capsule contains the basic crew life support The crew rides into orbit in the crew systems and all guidance and navigation ascent capsule (Figure 3-30). This pressurized equipment for the rendezvous with the ERV. vehicle can accommodate the crew of six, their EVA suits, and the samples gathered 3.6.3.6 Earth-Return Vehicle during the expedition and from experiments Returning the crew from Mars orbit to conducted in the surface habitat/laboratory. Earth is accomplished by the ERV which is Life support systems are designed for the composed of the TEI stage, the Earth-return relatively short flight to the waiting ERV. This transit habitat, and the ECCV. The ERV is ascent capsule does not have a heat shield, as delivered to Mars orbit with the TEI stage it is not intended for reentering the fully fueled, and it loiters there for nearly 4 atmosphere of Earth or Mars. Once the years before being used by the crew returning

3-86 Figure 3-29 Mars surface lander and biconic aeroshell.

Figure 3-30 Crew ascent capsule just after launch from Mars surface.

3-87 9 (m) 4 (m)

One center (core) 3.6 (m) dia spherical LO2 tanks

One center (core) 3.3 (m) dia spherical LOH4 tanks

6 (m)

Figure 3-31 Methane/LOX ascent stage configuration.

3-88 to Earth. For the return to Earth, the crew will stage, and liquid oxygen/liquid methane jettison the MAV and wait for the appropriate with the same engine used by the lander and departure time to leave the parking orbit. the MAV. With the 4-year loiter time in Mars During the 180-day return trip, the crew will orbit, propellant boiloff was the major design recondition themselves as much as possible consideration. Liquid hydrogen would for the return to an Earth gravity require active refrigeration for this extended environment, train for those procedures they period in orbit to avoid excessive boiloff will use during the entry phase, perform losses. Liquid oxygen/liquid methane boiloff science experiments and maintenance tasks, losses could be held to acceptable levels using and prepare reports. As they approach Earth, passive insulation and appropriate the crew will transfer to the ECCV, along with orientation of the vehicle while in Mars orbit the samples they are returning, and separate (to minimize radiative heat input from Mars, from the remainder of the ERV. The TEI stage the largest source). The 30 kWe solar power and the transit habitat will fly by Earth and system (used primarily for powering the ERV continue on into deep space. The crew in the on the return to Earth) is also on board and ECCV will deflect their trajectory slightly so could be used for active cooling of these that they reenter the Earth’s atmosphere and propellants. Based primarily on this trade-off, land on the surface. liquid oxygen and liquid methane were chosen as the TEI stage propellants. The propulsion system for the ERV is sized for the velocity change needed to move With this selection, the TEI propulsion the Earth return habitat and the ECCV from system uses two RL10-class engines modified the highly elliptical parking orbit at Mars to to burn LOX/CH4. Again, these are the same the fast-transit return trajectory to Earth. As engines developed for the ascent and descent with the TMI stage, the energetically stages, thereby reducing engine development demanding 2011 return trajectory was used to costs and improving maintainability. To size this system for a 180-day return; less achieve the velocity change for the 2011 fast- energetically demanding returns could be transit return requires approximately 52 accomplished faster or with larger return tonnes of liquid oxygen and liquid methane. payloads. The remainder of the TEI propulsion system, including tanks, structure, engines, and Several propellant and engine reaction control systems, has a dry mass of combinations were considered by the Mars approximately 5.2 tonnes. Study Team for the TEI propulsion system. The two options given the most consideration The return habitat is a duplicate of the were liquid hydrogen with a NERVA outbound transit/surface habitat used to go derivative engine comparable to the TMI to Mars but without the stores of consumables

3-89 in the surface habitat. As with the surface 3.6.3.7 Interplanetary Transportation Power habitats, the primary structure of this habitat Systems consists of a cylinder 7.5 meters in diameter A source of power will be required for all and 4.6 meters long with two elliptical end of the interplanetary transportation systems caps (overall length of 7.5 meters). The during the flight times to and, in the case of internal volume will be divided into two the ERV, from Mars. While several alternatives levels, oriented so that each “floor” will be a are available as a primary source of power for cylinder 7.5 meters in diameter and these vehicles, solar energy is readily approximately 3 meters in height. The available throughout these transit phases and primary and secondary structure, windows, photovoltaic energy is a known technology. hatches, docking mechanisms, power Thus, a basic photovoltaic power capability is distribution systems, life support, assumed for those vehicles that are operating environmental control, safety features, in interplanetary space. A source of stored stowage, waste management, power will also be needed for the communications, airlock function and crew interplanetary vehicles during periods of egress routes will be identical to the other eclipse and of array retraction prior to capture habitation elements. Table 3-14 details the into Mars orbit, and for vehicles not typically mass estimate for this habitat module. operating in interplanetary space (such as the The ECCV is similar in concept to the Mars surface lander, the MAV, and the ECCV). Apollo Command Module and is eventually During the eclipse periods and for the other used by the crew to enter the Earth’s vehicles, a regenerative fuel cell (RFC) system atmosphere and deliver the crew to a safe will be used to provide necessary power. landing on land. The ECCV will have the The most significant power requirements necessary heat shield for Earth reentry and for the interplanetary transportation system will be heavier than the ascent capsule come from the transit/surface habitat and the specialized only for that portion of the ERV. Table 3-15 shows the estimated power mission. This vehicle has all of the life requirements to support the six-person crew support, guidance and navigation, and for both nominal and powerdown emergency propulsion systems to keep the crew alive for mode. The life support system is a major several days and to maneuver the vehicle into constituent of the almost 30 kWe needed for the proper entry trajectory. Once the reentry these two vehicles under nominal conditions. phase has been completed, the ECCV will use The life support system is based on a partially a steerable parafoil to land at a designated closed air and water system design that per- location on the surface (Figure 3-32). The forms CO2 reduction, O2 and N2 generation, ECCV has an estimated mass of 5.5 tonnes. urine processing, and water processing (potable and hygiene). The emergency mode

3-90 Figure 3-32 ECCV returning to Earth on a steerable parafoil.

3-91 Table 3-14 Earth-Return Habitat Element Mass Breakdown

Subsystem Consumables Dry Mass Subsystem Mass Subtotal Subtotal (tonnes) (tonnes) (tonnes)

Physical/chemical life support 6.00 3.00 3.00 Plant growth 0.00 0.00 0.00 Crew accommodations 22.50 17.50 5.00 Health care 2.50 0.50 2.00 Structures 10.00 0.00 10.00 EVA 4.00 3.00 1.00 Electrical power distribution 0.50 0.00 0.50 Communications and information 1.50 0.00 1.50 management Thermal control 2.00 0.00 2.00 Power generation 0.00 0.00 0.00 Attitude control 0.00 0.00 0.00 Spares/growth/margin 3.50 0.00 3.50 Radiation shielding 0.00 0.00 0.00 Science 0.90 0.00 0.90 Crew 0.50 0.50 0.00

Total estimate 53.90 24.50 29.40

value is based on the life support system outbound transit/surface habitat can be operating in an open loop mode with safely powered down to 20 kWe during these reductions in noncritical operations. mission phases to save RFC mass and volume, and that the RFC and solar array will The solar array as it would appear on the remain with the transit/surface habitat to be ERV (Figure 3-33) is designed to produce the used on the surface as a backup system. required 30 kWe in Mars orbit at the worst- case distance from the Sun, 1.67 AU. The Based on the size of the energy storage energy storage system is sized to provide system, eclipse power requirement, and power before and after Mars orbit capture as available power from the array, it will take well as during attitude control, array seven orbits of Mars to fully charge the RFC. retraction, orbit capture, array extension The RFC delivers power when the solar array maneuvers, and orbit eclipse. A nominal is retracted during entry, descent, and landing power profile for these activities is shown in of the transit/surface habitat. The RFC can Figure 3-34. It is currently assumed that the also deliver 20 kWe for 24 hours after landing,

3-92 Table 3-15 Estimated Power Profile for Outbound and Return Transits

Element Mode Notes Nominal Emergency Life Support System (LSS) 12.00 8.00 Open Loop in Emergency Thermal Contract System (TCS) 2.20 2.20 Mode Galley 1.00 0.50 Emergency values Logistic Module 1.80 1.80 Derated from nominal where Airlock 0.60 0.10 appropriate Communications 0.50 0.50 Personal Quarters 0.40 0.00 Command Center 0.50 0.50 Values adapted from NAS8- Health Maintenance Facility (HMF) 1.70 0.00 37126, “Manned Mars System Data Management System 1.90 0.80 Study Audio/Video 0.40 0.10 Lab 0.70 0.00 Hygiene 0.70 0.00 SC/Utility Power 5.00 5.00 Total 29.40 19.50 and it will be the prime power source for the Utility Power” in Table 3-15) is estimated at 5 transit/surface habitat and crew until the kWe. This value is assumed as the power habitat is moved to its final location and requirement for the unmanned cargo-only connected to the main power grid. The RFC vehicles during the outbound transit. could also provide power for moving the Tables 3-16 and 3-17 show the mass habitat from the landing site to its final estimates for the two power systems emplacement location, assuming no solar discussed: the 30 kWe system used for the array deployment. habitats and the 5 kWe system used for the A duplicate of the solar array and RFC cargo flights. Both tables show the resulting system will be used on the ERV, saving system characteristics if the RFCs must be development costs for a unique system. All recharged over the course of one orbit versus other spacecraft discussed will use a subset of recharging them over seven orbits. The the RFC system (assumed to be modular or at savings in mass, volume, and array area are least manufactured in smaller units) used in obvious and support the choice to stay in the transit/surface habitat. The base power orbit for a longer period of time. load for vehicle avionics, communications, and the propulsion system (noted as “S/C

3-93 Figure 3-33 Solar array power source for interplanetary spacecraft. Figure 3-33 Solar array power source

3-94 30

Max. orbit eclipse, 4.2 hr Descent (2hr)

1st Sol 2nd Sol 6th Sol 7th Sol Transit from Earth Orbit 20 10 hr to Mars Orbit

AD AR 10.6 hr 10.6 hr 10 Power Level (kWe) 180 days

0 8 hr MO Time

NOTES: Solar arrays Time axis was not drawn to scale MO = Mars Orbit, period is 1 sol (Martian day = 25 hrs) Batteries or RFC AD = Array Deployment (4 hr) AR = Array Retraction (4 hr) Solar arrays and batteries

Figure 3-34 Nominal power profile for the transit/surface habitat.

3.6.4 Surface Systems autonomy and require support from the flight The surface systems assembled to crew or Earth-based supervisors only in support the long-duration science and extreme situations where built-in capabilities exploration activities of the Reference Mission cannot cope. consist of six major systems: a surface 3.6.4.1 Surface Habitat/Laboratory laboratory and habitat module, a bioregenerative life support system, ISRU The primary function of the Mars surface equipment, surface mobility systems (rovers), habitat/laboratory is to support the scientific extravehicular mobility systems (EVA suits or and research activities of the surface crews. space suits), and power systems. All of these The same structural cylinder (7.5 meters in systems, with the possible exception of the diameter, bi-level, and vertically oriented) EVA suits, are sent to Mars, landed on the used for the other habitat elements was used surface, deployed, and determined to be here, but it is more specialized for the functioning before departure of the flight research activities. It will operate only in 3/8 crew. This requires that each system be gravity. developed with a high degree of built-in

3-95 Table 3-16 30 kWe Power System With Fuel Cells and Solar Arrays

Power 1-Orbit 7-Orbit System Type Recharge Recharge

Mass Volume Array Area Mass Array Area Volume (m3) (kg) (m3) (m2) (kg) (m2)

Fuel Cell 1481 0.194 N/A 1102 3.83 N/A Radiator 259 3.260 47 190 1.5 35 Array 2971 N/A 918 1682 N/A 520

Total 4711 3.454 965 2974 5.38 555

Table 3-17 5 kWe Power System With Fuel Cells and Solar Arrays

Power 1-Orbit 7-Orbit System Type Recharge Recharge

Mass Volume Array Area Mass Array Area Volume (m3) (kg) (m3) (m2) (kg) (m2)

Fuel Cell 398 9.498 N/A 347 0.456 N/A Radiator 76 0.971 14 49 0.653 9 Array 795 N/A 246 431 N/A 138

Total 1269 1.469 260 827 1.109 147

3-96 This surface habitat/laboratory will be extended periods of time in the habitat/ one of the first elements landed on the surface laboratory. The primary airlock for EVA of Mars. Once moved to a suitable location activities will be located in this module (with (should the actual landing site prove backup capability in one of the other habitat unsuitable or to accommodate other modules) with an EVA suit maintenance and operational needs), this facility will be charging station located near the airlock. connected to the surface power systems and Table 3-18 details the estimated mass for this all internal subsystems will be activated. Only module. after these internal subsystems and other landed surface systems have been verified to 3.6.4.2 Life Support System be operating satisfactorily will the first crew An important reason for sending humans be launched from Earth. to live on and explore Mars is to determine The surface habitat/laboratory contains a whether human life is capable of surviving large stowage area on the first level and the and working productively there. The life second level is devoted entirely to the support system (LSS) for a Mars surface primary science and research laboratory. The mission will be an integral part of the mission stowage area will initially contain architecture, and must be viewed in terms of nonperishable consumables that can be sent its requirements to maintain the health and to the surface prior to the arrival of the first safety of the crew and its capability to crew. As these consumables are used, this minimize the dependence of a Mars outpost space will become available for other uses— on materials supplied from Earth. Proving likely to be plant growth and greenhouse- that human, and by extension animal and type experiments. The other subsystems of plant, life can inhabit another world and this module, such as the primary and become self-sufficient and productive will be secondary structure, windows, hatches, a major objective of this LSS. docking mechanisms, power distribution Four options were examined for use as systems, life support, environmental control, the LSS for the Mars surface facilities: open safety features, stowage, waste management, loop, physical/chemical, bioregenerative, and communications, airlock function, and crew cached stocks of consumable materials. egress routes, will be identical to the other •The open loop option is the simplest to habitats with a few exceptions. No crew implement but typically the most expensive quarters or accommodations will be included in terms of the mass required. For this option, in this module except for a minimal galley life support materials are constantly and minimal waste management facility. replenished from stored supplies as they are However, the life support subsystem will be used (for example, as air is breathed by the capable of supporting the entire crew should crew, it is dumped overboard and replaced it become necessary for the crew to spend

3-97 Table 3-18 Mars Surface Habitat/Laboratory Mass Breakdown

Subsystem Consumables Dry Mass Subsystem Mass Subtotal Subtotal (tonnes) (tonnes) (tonnes)

Physical/chemical life support 4.00 2.00 2.00 Plant growth 3.00 1.00 2.00 Crew accommodations 7.50 7.50 0.00 Health care 0.00 0.00 0.00 Structures 10.00 0.00 10.00 EVA 1.50 1.00 0.50 Electrical power distribution 0.50 0.00 0.50 Communications and information 1.50 0.00 1.50 management Thermal control 2.00 0.00 2.00 Power generation 0.00 0.00 0.00 Attitude control 0.00 0.00 0.00 Spares/growth/margin 5.50 0.00 5.00 Radiation shielding 0.00 0.00 0.00 Science 3.00 Uncertain 3.00 Crew 0.00 0.00 0.00

Total estimate 38.50 11.50 27.00

with “new” air). While not seriously considered, this option was carried for Life Support System, although it is often comparison purposes. described colloquially as a “greenhouse system.” •The physical/chemical option is typical of the systems used in current spacecraft •The cached stocks option makes use of and relies on a combination of physical the ISRU equipment already in place for processes and chemical reactions to manufacturing propellants to also make scrub impurities from the air and water. usable air and water for the crew. Trace amounts of the constituents of usable air •The bioregenerative option uses higher and water will be by-products (in fact plant life species to provide food, impurities that must be removed) of the revitalize air, and purify water. This type propellant manufacturing process. of approach is technically embodied in Capturing and storing these impurities the concept of a Controlled Ecological as well as oversizing some of the

3-98 production processes can allow the crew stay. A physical/chemical system was chosen to at least augment other elements of the due to the mature nature of the technology. LSS. Thus, the first habitat and the surface laboratory constitute the primary and first Combinations and hybrids of these backup (although not strictly a functional but options are also possible and were also rather a redundant backup) for the crew life examined for this report. Using a combination support. of systems or a hybrid system would provide more levels of functional redundancy and It is highly desirable for the second thus provide an attractive option for backup to use indigenous resources so that enhancing the viability of the Mars surface the backup life support objective and the live facilities as a safe haven. Figure 3-35 off the land objective are both met. Table 3-19 illustrates a hybrid system using physical/ compares the various options for the chemical and bioregenerative elements. combined LSSs with an open system. Each of these options was sized for a crew of six In this example, certain life support spending 600 days on the martian surface. functions, such as CO2 reduction and water purification, can be shared by both elements, Because of the life-critical nature of the while other functions, such as fresh food propellant manufacturing facility and the production, can only come from the high level of reliability that must be designed greenhouse. As an integrated system, neither into this system, the cached stocks option was element needs to provide 100 percent of the chosen as the second backup. However, full life support demand on a continuous demonstrating the capability to produce basis. Both elements however, should be foodstuffs and revitalize air and water using capable of being periodically throttled to bioregenerative processes is considered a satisfy from 0 percent to 100 percent of the mission-critical objective for the Reference LSS load. Mission. For that reason, an experimental bioregenerative life support system capable of The Reference Mission adopted the producing a small amount of food is included philosophy that life-critical systems (those as a science payload to be delivered for use by systems absolutely essential to ensure the the second crew. crew’s survival) should have two backup levels of functional redundancy. That is, if the Several options exist for the location of first two levels fail, the crew will not be in the experimental bioregenerative LSS. One is jeopardy, but will not be able to complete all to use the storage space in the surface mission objectives. As previously discussed, habitat/laboratory that will become available each habitat is equipped with a physical/ as consumables are used. This is the simplest chemical LSS capable of providing for the to implement but would require artificial entire crew for the duration of their surface lighting and would be restricted to the

3-99 SUPPLY RECYCLE HIGHWAY PATH

O H O LSS 2 2 FOOD H2OO2 EFFL. BUS

H O DISPOSAL 2 PATH O2

PHYS. / CHEM. CO2 BIO-REGEN.

INFL. BUS MASS CO2 H2O H2O CO2

WASTE ELECT. PRODUCT POWER HIGHWAY HIGHWAY

Figure 3-35 Hybrid LSS process distribution.

Table 3-19 LSS Mass, Volume, Power Comparison.

Functional Mass Volume Maximum ∆ Architecture Redundant (mt) (m^3) Power Over Levels Open Loop (kW)

Open Loop 1 180 290 0

Physical/Chemical with Cached 2 60 470 7 Stocks Bioregenerative with Cached 2 60 410 60 Stocks Hybrid Physical/Chemical and Bioregenerative with Cached 3 80 600 60 Stocks

3-100 volume available in the storage area. Two first follow-up mission. Each ISRU plant will other options involve attaching an external produce propellants for at least two MAV pressurized structure to one of the habitat missions. However, only the first plant is modules. One external option would use a required to produce life support caches. hard opaque structure for the external shell For each MAV mission, a plant is and would also require artificial lighting. The required to produce 20 tonnes of oxygen and other external option would use an inflatable methane propellants at a 3.5 to 1 ratio: Each transparent structure for the external shell. plant must produce 5.8 tonnes of methane Natural sunlight would be used to illuminate and 20.2 tonnes of oxygen. Further, the first the plants which would reduce the power ISRU system is required to produce 23.2 needed by the system; however, the potential tonnes of water, 4.5 tonnes of breathing risk of a puncture due to natural or human- oxygen, and 3.9 tonnes of nitrogen/argon derived events would be increased. inert buffer gasses for use by any of the three In either external scheme, the greenhouse Mars crews. The system liquefies and stores atmospheric volumes would normally all of these materials as redundant life communicate directly with the atmospheric support reserves or for later use by the MAV. volume of the habitat without further The approach to ISRU production uses processing, but could be sealed off in the martian atmosphere for feedstock and contingencies. The greenhouse(s) could be imports hydrogen from Earth. The main erected or inflated at the convenience of the processes used are common to both ISRU crew. The loss of a greenhouse module for plants. The significant difference between the any reason, such as puncture, mechanical or two is that the second plant is smaller and electrical failure, or loss of shielding integrity, excludes equipment for buffer gas extraction. would not seriously impact overall mission Should sources of indigenous and readily success. available water be found, this system could be simplified. 3.6.4.3 In Situ Resource Utilization

ISRU for the Reference Mission provides 3.6.4.3.1 Processes two basic resources: propellants for the MAV The Mars atmosphere, which is used as a and cached reserves for the LSSs. Using feedstock resource, is composed primarily of indigenous resources to satisfy these needs carbon dioxide with just over 3 percent instead of transporting resources from Earth nitrogen and argon. The ISRU plants must be reduces launch mass and thus mission cost. capable of converting the carbon dioxide to ISRU production for the Reference Mission methane, oxygen, and water. Since hydrogen includes two virtually redundant ISRU plants, is not substantially present in the atmosphere the first delivered before the initial piloted in gaseous form and indigenous sources of mission and the second delivered prior to the

3-101 water are uncertain, hydrogen must be Water electrolysis is well known and has imported from Earth. The first plant must also been used for numerous terrestrial be capable of extracting the nitrogen and applications for many years. The combined argon for buffer gas reserves. The reference Sabatier and electrolysis processes generate ISRU system uses Sabatier, water electrolysis, oxygen and methane for use as propellants at carbon dioxide electrolysis, and buffer gas a mass ratio of 2:1. In this combined process absorption processes to achieve these ends. case, the hydrogen is recycled into the Sabatier process so that 0.25 tonnes of •Methane production - The Sabatier hydrogen are needed for each tonne of reaction was discovered by French methane. The engines selected for the chemist P. Sabatier in the nineteenth Reference Mission use oxygen and methane at century and is one of the most often a mass ratio of 3.5 to 1. Therefore, an cited for ISRU on Mars (Sullivan, et al., additional source of oxygen is needed to 1995). The reaction converts carbon to avoid overproduction of methane. methane and water by reacting it with imported hydrogen at elevated The carbon dioxide electrolysis process is temperatures. This process is also used in the Reference Mission to provide the commonly used in closed physical/ needed additional oxygen. The process chemical LSSs for reduction of metabolic converts the atmospheric carbon dioxide carbon dioxide. It results in a water to directly into oxygen and carbon monoxide methane mass ratio of 2.25:1 and using zirconia cells at high temperature. The requires 0.5 tonnes of hydrogen for each zirconia cell system is not as well developed tonne of methane produced. The as the Sabatier process but is under resultant methane is stored cryogenically development (Sridhar, et al., 1991; Ramohalli, as fuel. The water can either be used et al., 1989; and Colvin, et al., 1991). This directly as cached life support reserves process eliminates the overproduction of or can be broken down into oxygen and methane during propellant production except hydrogen to be recycled. during the first mission when the Sabatier- produced water is also needed. •Oxygen production - Oxygen production is accomplished with two different The two strong alternatives to carbon processes. The Reference Mission uses dioxide electrolysis—methane pyrolysis and both water electrolysis to produce reverse water gas shift—were not studied in- oxygen from water produced in the depth for the Reference Mission report, but plant and carbon dioxide electrolysis to they should be considered seriously in further directly convert the Mars atmosphere to studies of manned Mars missions. oxygen.

3-102 •Buffer gas extraction - The buffer gas 3.6.4.3.2 Initial ISRU Plant extraction process has not been The first ISRU plant is delivered to Mars examined in detail during this study. It over a year prior to the first departure of will most likely be a nitrogen and argon humans from Earth, and during that year the absorption process in which compressed plant produces all the propellants and life atmosphere is passed over a bed of support caches that will be needed. Thus, material which absorbs the nitrogen and humans do not even leave Earth until argon. The gases are then released by reserves and return propellants are available. heating the bed and the products are This plant also produces propellants for the passed on to the cooling and storage MAV mission of the third crew in the overall system. Parallel chambers are used so Reference Mission scenario. that one bed is absorbing in the presence of atmosphere while the other is A schematic of this initial plant is shown releasing its captured gases. in Figure 3-36. The plant integrates all the processes needed for both propellant and life •Ancillary Systems - Systems for support products. The water electrolyzer is atmosphere intake, product liquefaction, not used in the plant during the first period of and product storage and transfer will be operation. Because of the total mass of the needed. These systems have not been water cache, all of the water produced by the detailed for the Reference Mission at this Sabatier reactor is stored and the carbon stage of study but their necessary dioxide electrolysis reactor is responsible for functions can be described. The filter producing all the oxygen needed. In addition, and compressor equipment cleans the over 10 tonnes of excess methane are martian atmosphere of dust and produced as a by-product of the water compresses it to a pressure usable by the production process for the LSS cache. rest of the ISRU plant. Product liquefaction must include cryogenic When the plant is operated for the third liquefaction of oxygen, methane and MAV launch propellants, the water nitrogen as well as condensation of the electrolyzer is brought on-line. Instead of water stored as cached reserves. Storage being condensed, the water from the Sabatier systems will include cryogenic tanks for reactor is split by the electrolyzer into cached oxygen and buffer gasses. An hydrogen (which is recycled to the Sabatier expandable bladder-type tank is reactor) and oxygen (which is liquefied and anticipated for cached water. Propellant sent to the MAV tanks). For this operation of storage will be accomplished in the MAV the plant, no methane overproduction is tanks and so is not considered part of the needed. ISRU system.

3-103 Buffer Gas Extraction

Filter/ Mars O2(trace) Compressor Atmosphere H2O (trace)

H2

N2/Ar CO2

CO Electrolysis 2 H2 Water Electrolysis CO NC Vent NC Water Condenser Buffer Gas Sabatier Cryo Cooler NC H 0 CH4 CH4 2 MAV Vent MAV First Second Stage Stage O2 CH4 CH4

Buffer gas storage cache Cryo Cooler Breathing Water Storage O2 Storage Cache Cache O2 O2

Figure 3-36 Schematic of the first ISRU plant.

The size of the ISRU plant has only been 3.6.4.3.3 Second ISRU Plant estimated parametrically. These estimates are The second ISRU plant is delivered at based on some previous work on the options essentially the same time as the arrival of the for ISRU and on the rates needed to produce first crew on Mars. This allows time for requisite materials over a 15-month period. propellant production prior to the Earth The mass and power requirements for this departure of the second crew. The second plant are given in Table 3-20. The power plant is only charged with production of requirements represent those of the plant’s propellants since, the life support reserves are initial period of operation. presumably still present.

3-104 Table 3-20 Mass and Power Estimates for the First ISRU Plant

Plant Component Production Rate Component Mass Component Power (per day) (kg) (kWe)

Compressor 269.7 kg 716 4.09

CO2 Electrolysis 53.2 kg 2128 63.31 Sabatier 22.9 kg 504 1.15

H2O Electrolysis 27.8 kg 778 0.00 Buffer Gas Extraction 8.7 kg 23 0.13

Cryogenic Coolers 84.8 kg 653 3.59

The plant schematic is essentially the provided for basic maintenance and same as that shown in Figure 3-36. The operations activities as well as for exploration second plant does not include the buffer gas of the surface. Prior to the first crew’s arrival extraction, liquefaction, and storage and during all subsequent periods whether a equipment or the water condensation and crew is present or not, exploration at short storage equipment. Further, the size of the and long ranges will be performed by reactors is reduced because of the lower automated rovers. Surface facility setup production rates needed. Table 3-21 shows the activities will require rovers acting under the estimated mass and power requirements for supervision of Earth-based operators. this plant. Plant operations are the same as Maintenance and operations by the surface those of the first plant during its second crews can be more productive with the period: All Sabatier-produced water is availability of mobile utility systems. And electrolyzed, and the extra oxygen needed is finally, long-range, long-duration exploration produced by the carbon dioxide electrolyzer. by the surface crews will be possible only with the use of pressurized, autonomous 3.6.4.4 Surface Mobility rovers.

Mobility on a local scale and regional The Reference Mission identifies three scale will be required during all phases of the classes of mobility systems, based on the time surface exploration of the Reference Mission. and distance to be spent away from the The basic objectives for the Reference Mission surface habitats. require that a variety of mobility systems be

3-105 Table 3-21 Mass and Power Estimates for the Second ISRU Plant

Plant Component Production Rate Component Mass Component Power (per day) (kg) (kWe)

Compressor 87.8 kg atm 233 1.33

CO2 Electrolysis 18.5 kg O2 740 22.00

Sabatier 12.4 kg CH4 272 0.62

H2O Electrolysis 27.8 kg H2O 778 5.79 Cryogenic Coolers 30.8 kg 238 2.3

•Immediate vicinity of the surface base distance will be determined by their facilities: hundreds of meters and the 6- capability to walk back to the outpost within to 8-hour limit of the EVA portable LSS the time set by the recharge limits of the portable LSS. During these activities, the EVA •Local vicinity of the surface base facility: crew will have a variety of tools, including several kilometers and the 6- to 8-hour rovers, carts, and wagons, available for use. limit of the EVA portable LSS For distances perhaps beyond a kilometer •Regional distances: a radius of up to 500 from the habitats but less than 10 kilometers km in exploration sorties that allow 10 distant, exploration will be assisted by workdays to be spent at a particular unpressurized self-propelled rovers. This remote site, and with a transit speed rover is functionally the same as the Lunar such that less than half of the excursion Rover Vehicle used in the Apollo Program time is used for travel (for example, for and is meant to assist the EVA crews by 10 workdays, no more than 5 days to transporting them and their equipment over reach the site and 5 days to return). relatively short distances. Figure 3-37 These divisions resulted in three basic illustrates one concept for this rover (partially rover types and a number of other mobility hidden behind one of the teleoperated long- systems to support the kinds of activities at range rovers) with a gabled radiator above these ranges and for these amounts of time. the aft end. This rover is driven by six cone- On the local scale, any time the crew is shaped wheels and has an estimated mass of outside of the habitat(s) they will be in EVA 4.4 tonnes. Three of these vehicles will be part suits and will be able to operate at some of the cargo carried to the surface for use in distance from the habitat. The maximum and around the surface facilities.

3-106 On the regional scale, beyond the safe this rover is the power system. The choice of range for exploration on foot or in the specific power system is discussed in a unpressurized rovers, crews will explore in later section. However, this system will be pressurized rovers, allowing them to operate mounted on a separate trailer to be towed by for the most part in a shirtsleeve the rover whenever it is in operation. At times environment. Figure 3-38 illustrates one when the rover is dormant, the power trailer possible concept for this rover. The rover is can be used for other purposes, including its assumed to have a nominal crew of two use as a backup power source for any of the people, but can carry four in an emergency. surface facilities. Two pressurized rovers will Normally, the rover would be maneuvered be carried to the surface. This allows for and EVAs would be conducted only during redundancy in this function, including the daylight hours, but sufficient power will be possibility of rescuing the crew from a available to conduct selected investigations at disabled rover located at a distance from the night. Crew accommodations inside the rover habitats. Each rover is driven by four cone- will be relatively simple: a drive station, a shaped wheels and is estimated to have a work station, hygiene facilities, a galley, and mass of 16.5 tonnes. sleep facilities. An airlock on this rover will be Exploration at a regional scale will also capable of allowing not only surface access be undertaken by small teleoperated rovers. for an EVA crew, but also direct connection to The foreground of Figure 3-38 illustrates one the habitat, thus precluding the need for an possible concept for this rover. The main EVA to transfer either to or from the rover. purpose for these rovers is to explore the Each day on an excursion away from the martian surface at long distances, hundreds to main surface facilities, the rover has the thousands of kilometers, from the habitats. capability of supporting up to 16 person- The activities carried out by this type of rover hours of EVAs. Facilities for recharging the will be to conduct scientific investigations, portable LSSs and for making minor repairs collect and return samples to the habitats, and to the EVA suits are also included. The work scout possible locations for human crews to station will be used, in part, to operate two investigate in more detail. Three of these mechanical arms that can be used to rovers will be delivered as part of the first manipulate objects outside the rover without cargo mission and will be supervised from leaving the pressurized environment. These Earth during the time between landing and arms, along with other mobility subsystems, the arrival of the first crew. Determining sites can also be operated remotely by Earth-based for the crews to investigate and safe routes to personnel. This feature is required to allow the sites will be the primary activity before many of the deployment, setup, and the first crew arrives and during those monitoring activities to be carried out prior to periods when no crew is at the surface base. the arrival of the first crew. A final feature of When a crew is on the martian surface, these

3-107 Figure 3-37 Concepts for the unpressurized and automated surface rovers.

3-108 Figure 3-38 Concept for the large pressurized surface rover.

3-109 rovers will be available for teleoperation by allow the crew to safely exit and enter the the crews. Focused exploration, sample pressurized habitats. collection, and scientific measurements will The EVA system will have the critical be the main tasks for these rovers while under functional elements of a pressure shell, the control of the surface crew, who will be atmospheric and thermal control, able to operate these rovers from the communications, monitoring and display, and shirtsleeve environment of the surface nourishment and hygiene. Balancing the habitat/laboratory. Each rover is estimated to desire for high mobility and dexterity against have a mass of 440 kilograms. accumulated risk to the explorer will be a This range of mobility systems will allow major design requirement on a Mars EVA exploration activities to be carried out system. Lightweight and ease of maintenance continuously once the first cargo mission has will also contribute to the design. Specific delivered its payload to the martian surface. concepts for an EVA suit that will satisfy these The variety of range requirements and surface requirements were not investigated in this activities leads to a suite of mobility systems study. Further effort will be required to that have overlapping capabilities. translate these general needs into specific requirements and an actual implementation. 3.6.4.5 EVA Systems The airlock system, although integral The ability for individual crew members with the habitation system, was developed as to move around and conduct useful tasks an independent element capable of being outside the pressurized habitats will be a “plugged” or relocated as the mission necessary capability for the Reference requires. Because EVA will be a substantial Mission. EVA tasks will consist of element of any planetary surface mission, the constructing and maintaining the surface design and location of the associated airlock facilities, and conducting a scientific facilities will have a major impact on the exploration program encompassing geologic internal architecture of each pressurized field work, sample collection, and element. deployment, operation, and maintenance of A conceptual airlock configuration was instruments. EVA systems provide a primary prepared (Figure 3-39). In the foreground of operational element and a critical component this conceptual design is an airlock sized for of the crew safety system and must be two suited crew members. In the rear of the integrated into the design of a habitation illustration is a facility for EVA suit system during the very early stages. Two maintenance and consumables servicing. systems will make EVA possible for the crews: Each habitat will have an airlock located an EVA suit designed for use in the martian within it. The maintenance and consumables environment and an airlock system that will

3-110 synergies that would suggest common hardware (duplicates of the same or similar design) or multiuse (reuse system in a different application or location) wherever prudent, the specific requirements for the fixed and mobile power sources were examined individually.

3.6.4.6.1 Fixed Surface Power Systems

To best determine the type and design of the fixed power system, an estimated power profile was developed and is shown in Figure Figure 3-39 Conceptual airlock and 3-40. EVA suit maintenance facility. The power system must be one of the servicing facility will be located in the surface first elements deployed because it provides habitat/laboratory. power to produce the life support cache and ascent vehicle propellants prior to the launch 3.6.4.6 Surface Power Systems of the first crew. Approximately 370 days will A source of power will be required for a be available to produce the required life number of diverse systems operating on the support cache and ascent propellant. surface of Mars. A large fixed power source is However, this will be reduced by the time to required to support the propellant deploy the power system. With an estimated manufacturing facility and the surface power system deployment time of 30 to 60 habitats. A mobile source of power is required days, about 320 days remain for producing to support the three categories of rovers that these products. An initial 60 kWe power level will move crew and scientific instruments was determined by this required deployment across the martian surface. Various power time and the energy required to produce the system options were reviewed for their life support cache and ascent vehicle appropriateness to meet mission propellants during the time remaining. As the requirements and guidelines for these surface outpost reaches full maturity, power levels systems. Contending power system approach 160 kWe due to increased habitation technologies include solar, nuclear, isotopic, volumes and life support capability. electrochemical, and chemical for both the Significant design requirements are also fixed and mobile power source. placed on all the surface equipment delivered While all surface element power system on the initial cargo flights. Each system must requirements were assessed for application be deployed to its respective locations and

3-111 175

150

125 P o w 100 e r 75 kWe

50

25

1 2 34 56 7 Years After First Cargo Landing Figure 3-40 Mars surface power profile. function autonomously for almost 2 years. The power management, transmission, Crew safety and well-being demands and distribution system masses (at 95 percent reliability and robustness in all surface efficiency) have been included in each of the elements. (Part of this risk is mitigated by system sizing estimates. Transmission cable backup and redundant systems or systems masses were calculated using 500 volts due to that can perform multiple functions.) These the Paschen breakdown limit associated with requirements all impact the design and Mars’ atmospheric pressure. (For a wide selection of the power system for the central range of conditions, exposed conductors at an base. electrical potential greater than 500 volts could experience large power drains due to To meet the evolutionary power atmospheric discharges.) requirements of the base, two types of power systems were evaluated: nuclear and solar. Due to the potential radiation hazard of a Table 3-22 shows estimated mass, volume, nuclear power source, the nuclear power and area for each of these options. system is configured with a completely

3-112 Table 3-22 Characteristics for Fixed Surface Power System Options

Main Power Type Mass Volume Area (m2) System (kWe) (MT) (m3)

NUCLEAR- 14 42 SP-100 type, low-temp, stainless 160 321 radiator area steel, dynamic conversion, 4-Pi shielding

SOLAR - tracking, 120 19.6 341 6,400 array area O.D. = 0.4 45,000 field area

SOLAR - nontracking, 33.5 686 13,000 array area O.D. = 0.4 39,000 field area SOLAR - tracking, 7,600 array area Backup 40 14 390 O.D. = 6.0 53,000 field area

SOLAR - nontracking, 26 816 16,000 array area O.D. = 6.0 48,000 field area

Emergency Use Pressurized Rover Power System (See Table 3-21)

O.D. - optical depth enveloping shield for remote deployment and mission requirement, but it will not be turned is integrated with a mobile platform. The on unless required. entire system is deployed from the landing The second option, a solar power system, site (trailing distribution cables) to a site at requires array panels to supply the main base least 1 kilometer from the base. It is planned load and recharge the energy storage for to use one of the rovers for this task. Power nighttime operations. The primary 120 kWe from the rover will be used to start up the system was sized to produce required power power system, deploy radiators, and obtain during winter diurnal cycles at the equator. operating conditions. All of these activities The backup habitat power system was will be supervised remotely by personnel on designed to operate at worst-case global dust Earth and will be performed in a manner that storm conditions, characterized by an optical will minimize the risk to this critical piece of depth (O.D.) equal to 6.0, since these equipment. The first nuclear power system conditions could be present at the base when will be capable of delivering the full base an emergency power situation arose. Under needs of 160 kWe. A second system is nominal conditions, these two systems were delivered during the first opportunity and is assumed to be operating in unison to provide deployed to satisfy the fail-operational the maximum 160 kWe required for the

3-113 mature base. The ISRU plant was not 3.6.4.6.2 Mobile Surface Power Systems considered a life-critical function so the The other major category of surface power system was designed to produce full systems needing a power source will be the power at an O.D. of 0.4 or a clear Mars sky. rovers. The three types of rovers identified, Both sun tracking and nontracking arrays long-range pressurized, local unpressurized, were evaluated. The solar tracking array total and long-range robotics, each have power land area is greater that the nontracking requirements driven by their range and the because of the required panel spacing needed systems they must support. Several power to eliminate shadows from one panel upon source options were evaluated for the rovers, the other. including solar arrays/RFCs, combustion O.D., or the intensity of the solar engines, and isotopes. Solar array systems radiation reaching the surface of Mars, has a were not considered due to the large size of significant impact on system size and mass. the array needed to support each vehicle. For example, if the entire 160 kWe were solar The long-range pressurized rover must generated, the array field would encompass be able to support a crew of 2 to 4, with a 500- about 11 (O.D. = 0.4) to 40 (O.D. = 6.0) football km range sortie (5 days out, 10 days at site, 5 fields. In addition, the need for prompt days back). The power estimate for this rover telerobotic emplacement of the array panels is 10 kWe continuous. It is anticipated that the and interconnecting cables would present a pressurized, regional rover or its power significant challenge. Dust erosion, dust system would be used to assist in the accumulation, and wind stresses on the array deployment of the main power system, panels raise power system lifetime issues. For situate future habitat modules, and serve as these reasons, nuclear power was deemed the backup emergency power when required. A most appropriate primary power source for desirable feature for the rover power system the fixed surface power system. However, use is that it be mounted on its own cart. This of the “in-space” solar array and fuel cell would add considerable versatility to its use power system is assumed as the habitat when the rover is not on a sortie. emergency/backup power systems, which could be stowed until needed. The MAVs will The local unpressurized rover is also be provided with this same solar array conceptually the same as the Apollo lunar backup system to ensure that the rover. It would function to transport the crew manufactured propellants are maintained in 10's of kilometers, 3 hours out and back, and 4 their cryogenic state should power from the hours at the site. nuclear system be lost (Withraw, et al., 1993). Table 3-23 shows the estimated mass, volume, and array or radiator area for the four power system options listed.

3-114 The Dynamic Isotope Power System scenario, anticipating suspended operations (DIPS) was considered primarily for its low during potential global dust storm season. mass and significantly lower radiator size Methane is a possible fuel for the rover compared to the photovoltaic array (PVA) since the propellant plant could produce area. The 238Pu isotope has a half life of 88 additional fuel, given that extra hydrogen is years and can be the same design as the flight brought from Earth. Methane could be used proven radioisotope thermoelectric generator in an appropriately designed fuel cell. The (RTG). The isotope fuel would be reloadable reactant water would be returned and fed into other power units in the event of a through an electrolyzer to capture the failure, thus preserving its utility. Another hydrogen. However, once the water has been feature of isotope fuel is that it does not need electrolyzed into H and O , which the fuel to be recharged and is always ready as a 2 2 cell actually uses to operate, it is not prudent backup, emergency power source from an energy utilization standpoint to make independent of solar availability or methane again. Storing and maintaining atmospheric conditions. However, the 238Pu reactants on the rover also needs further isotope availability, quantity, and cost are study. issues to be addressed. A methane-burning internal combustion The PV/RFC power option seems engine could be used to operate either rover. impractical for the regional rover due to the However, combustion materials would need large array area. The arrays would have to be to be collected to reclaim the H . sized to provide required power output 2 during a local dust storm, the worst-case

Table 3-23 Rover Power System Characteristics

Mass Area Mass Area Power System Volume (m3) Volume (m3) (MT) (m2) (MT) (m2)

Regional Rover Local Rover

Dynamic isotope 1.1 10 33 0.5 4 16

66 1,275 2.8 Photovoltaic (PV) RFC (RFC-4) recharge by fueling PV-62)

Primary Fuel Cell 6.5 29 13 0.160 1 6

Methane/Oxygen Internal 12 36 n/a 0.160 0.4 n/a Combustion Engine

3-115 Given these system characteristics, the weather and provide global maps of martian DIPS system was selected for the long-range surface topography and mineral distribution. pressurized rover, and the primary fuel cell The Mars Pathfinder will validate entry, was selected for the local rover. The DIPS descent, and landing technologies and will system can be another level of functional also deploy a microrover on the surface to redundancy for the base systems, and the analyze the elemental composition of martian small amounts of radiation emitted can be rocks and soil. mitigated by a small shield and distance to NASA’s Mars Surveyor Program will the rover crew. The primary fuel cell would continue the robotic exploration of Mars with meet the local rover requirements at less mass two spacecraft launches planned during each than other options. However, this power of the 1998, 2001, and 2003 opportunities. A system design assumes refueling after every Mars sample return mission is scheduled for sortie. The power system for the long-range 2005. The goals of the Mars Surveyor Program robotic rover was not specifically addressed are to expand our knowledge of the geology in this analysis. However, the long range over and resources on Mars, to understand the rugged terrain and long duration of this meteorology and climate history, and to rover’s missions will likely drive the selection continue the search for evidence of past life. to an RTG- or DIPS-type system. 3.7.2 Mars Sample Return With ISRU 3.7 Robotic Precursors Detailed laboratory analyses of martian Robotic precursor missions will play a rock, soil, and atmosphere samples at Earth significant role in two important facets of the will provide essential information needed Reference Mission. The first will be to gather before sending humans to Mars. In addition information about Mars that will be used to to an understanding of the martian determine specific activities the crew will environment, a sample return mission will perform and where they will perform them. afford the opportunity to validate the The second will be to land, deploy, operate, technology of ISRU for propellant production. and maintain a significant portion of the As discussed in Section 3.6.4.3, ISRU is a surface systems prior to the arrival of the critical technology for the Reference Mission. crew. To ensure that this technology is available for the human missions, it should be 3.7.1 Current Robotic Program Plans demonstrated on the Mars sample return in In November and December 1996, NASA 2005. launched two missions to Mars: the Mars Global Surveyor (MGS) and the Mars Pathfinder lander. MGS will monitor global

3-116 3.7.3 Human Exploration Precursor various candidate sites. Detailed maps of Needs candidate landing sites built from data Robotic precursor missions offer the gathered by these precursor missions will capability to demonstrate and validate the define the safety and operational hazards of performance of key technologies that are the sites, as well as confirm access to essential to the Reference Mission (such as scientifically interesting locations and ISRU, aerobraking and aerocapture at Mars) resources. and to provide information needed for site In summary, then, the Reference Mission selection. assumes a set of robotic precursor missions Critical to selection of the landing site for which includes: the humans will be the availability of •The Mars Surveyor Program indigenous resources, and of paramount •A Mars sample return mission in 2005 importance is water. Precursor missions which also demonstrates in situ which can identify the location and propellant production accessibility of water will be invaluable in the Mars exploration program. To satisfy the •Other sample return missions to various human habitation objectives in particular, it interesting regions would be highly desirable to locate an •A demonstration of aerobraking/ outpost site where water can be readily aerocapture extracted from minerals or from subsurface deposits. Such a determination may only be •Mission(s) to search for resources, possible from data collected by a surface particularly water mission. •Site reconnaissance landers to aid in the With the three human missions all selection of the human landing site landing at the same site, selection of that The last two mission types may have landing site is very important. The location their objectives incorporated into the Mars chosen must permit the objectives of the Surveyor Program or the Mars sample return Reference Mission to be achieved. mission; or a separate set of missions may be Consequently, the site will be chosen on the required. basis of proximity to a region of high science yield, availability of water or other 3.7.4 Autonomous Deployment of indigenous resources, and operations Surface and Orbital Elements considerations such as a hazard-free terrain As described in Section 3.5.3.2, a key for safe landing and surface mobility. Final strategy of the Reference Mission is to use a site selection may require several robotic site split mission concept that will allow reconnaissance landers to be sent to survey

3-117 unmanned cargo to be sent to Mars on low •Provision of the facilities and an energy, longer-transit-time trajectories. These environment which allow users (such as unmanned elements must arrive at Mars and scientists, payload specialists, and to an be verified to be operating properly before the extent crew members) to conduct human crew is launched from Earth. The activities that will enhance the mission arrival, precision landing, deployment, and objectives. operation of these surface or orbital elements •Successful management and operation of will be performed using robotic systems. The the overall program and supporting detailed nature of these robotic systems was organizations. This requires defining not examined as part of this study; however, roles and responsibilities and the discussion of the surface facilities and the establishing a path of authority. Program nature of the operations involved to set up, and mission goals and objectives must maintain, and, if necessary, repair these be outlined so that management facilities can well be imagined. This area of responsibilities are clear and direct. technology development will be a very active Confusing or conflicting objectives can one to meet the needs of the Reference result in loss of resources, the most Mission. important of which are time and money. In addition, minimizing layers of 3.8 Ground Support and Facilities authority will help avoid prolonged Operations operational decision-making activities. The overall goal of mission operations is This is key when considering large, to provide a framework for planning, complex programs such as the Reference managing, and conducting activities which Mission. achieve mission objectives. (In general, As with the discussion of crew operations mission objectives can be considered all (Section 3.4), specific hardware, software, and activities which maintain and support human system recommendations will not be made in presence and support scientific research this section. Guidelines for the organization during the mission.) Achieving this and management of operations are put operational goal requires successful forward as foundation on which an actual accomplishment of the following functions. operations philosophy and detailed plan •Safe and efficient operation of all should be built. resources (includes, but is not limited to, The organization of supporting facilities vehicles, support facilities, training must follow the lower costing and innovative facilities, scientific and systems data, and approaches being taken by other areas of the personnel knowledge and experience Reference Mission. One way of achieving this bases).

3-118 is to use the related expertise and benefit of involving system and payloads functionality of existing facilities to keep to a experts in the overall planning, yet giving minimum the layers of authority and crews the flexibility to execute the tasks. This overhead in the program and take advantage approach differs from current Space Shuttle of the existing knowledge bases at each operations where detailed plans are prepared facility. Proper and efficient organization of by ground personnel, crew members execute mission operations and support facilities is the plans, and ground personnel monitor in required for any program to be successful. near real-time. The crew members are fully involved in execution but do little in terms of The Reference Mission has the added planning. The proposed method for the complication of being a program with phases Reference Mission would take advantage of that cannot be supported with near real-time the unique perspective of crew members in a operations. Planetary surface operations pose new environment but would not restrict their unique operational considerations on the activities because of the mission’s remote organization of ground support and facilities. nature. Additionally, it places the Near real-time ground support, as provided responsibility of mission success with the for current manned space programs, is not crew, while the overall responsibility for possible. A move toward autonomy in vehicle prioritizing activities in support of mission operations, failure recognition and resolution, objectives resides with Earth-based support. and mission planning is needed; and ground support must be structured to support these After dividing functional responsibilities needs. Some of the specific criteria required between Earth-based support and crew, the for allocating functions between ground support may be structured to manage the support and the Mars surface base will be the appropriate functions. To accomplish mission available resources at the remote site versus objectives while maintaining the first on Earth, criticality of functions for crew operational objective of safe and efficient safety and mission success, and desired time operation of all resources, Earth-based and resources available for achieving support can be organizationally separated scientific mission objectives. into systems operations and science operations, provided a well-defined interface In general, due to the uniqueness of exists between the two. The systems planetary surface operations, Earth-based operations team would be responsible for support should manage and monitor conducting the safe and efficient operation of operations planning and execution, and crew all resources, while the science operations members should be responsible for operations team would be responsible for conducting planning and execution. Crew members will activities which support scientific research. be told what tasks to do or what objectives to Such an organizational structure would accomplish, but not how to do it. This has the

3-119 dictate two separate operations teams with of program resources. Thus, the systems distinct priorities and responsibilities yet the operations team has the responsibility for same operational goal. conducting the safe and efficient operation of all such resources and consists of Crew and vehicle safety are always of representatives from each of the primary primary concern. When those are ensured, systems (power, propulsion, environmental, science activities become the highest priority. electrical, etc.) used throughout the various To accommodate this hierarchy of priorities mission phases. This organizational structure within the operations management structure, is similar to current flight vehicle operations the overall operations manager should reside where representatives for each system are within systems operations. A science responsible for verifying the system’s operations manager, who heads the science operational functionality. Each system operations team, should organizationally be representative will have an appropriate in support of the operations manager. Various support team of personnel familiar with the levels of interfaces between systems engineers hardware and software of that system. and science team members must exist to maximize the amount of science and mission Real-time operational support will be objectives that can be accomplished. For applicable only during launch, Earth orbit (for example, a proposed science activity may vehicle and crew checkout), and Earth entry need systems information for its planning and phases. As a result, the systems operations feasibility studies, and such information, team will function in a response, tracking, including providing access to the systems’ and planning mode throughout most of the experts, must be made available. There may other mission phases. Thus, Earth-based be a few overlapping areas of responsibility operations will be a checks and balances between the systems and science teams. (In function analogous to the mission the area of crew health and safety, for engineering functions executed during Space example, scientific investigators doing Shuttle missions. Hardware and software biomedical research on the crews will have to documentation will be available to the crew interface with the systems medical team on board for real-time systems operations and responsible for maintaining crew health.) failure response. However, Earth-based Avenues for such interaction and exchange support must be provided for instances where must be provided to ensure mission success. documentation is limited or does not cover a particular situation. 3.8.1 Systems Operations Except for the above mentioned near Systems operations are those tasks which real-time mission phases, data monitoring by keep elements of the program in operational Earth-based personnel must be limited to condition and support productive utilization periodic evaluations. Data and

3-120 communication constraints will make real- the primary interface between the science time system monitoring by Earth-based team and the operations manager. personnel impractical and unfeasible. Failures As science activities (such as initial and other systems issues will be worked by investigations, clarification of previous Earth-based personnel on an as needed basis research, and follow-up investigations) are and in support of long-term trend analysis. proposed by various principle investigators, Vehicle and system maintenance and the science team will evaluate the proposed checkout will be evaluated by the Earth-based research, determine feasibility and systems experts to assist in crew monitoring appropriateness of the study, and select and verification. Consumables management appropriate crew activities based on available such as usage planning and tracking will be time and personnel. This process is similar to done by the crew (with some degree of the process used by the National Science automation) with Earth-based personnel Foundation for the U.S. Antarctic Program doing verification only. which has successfully operated remote scientific bases in Antarctica since 1970 3.8.2 Science Operations (Buoni, 1990). Selected science proposals will The science operations team’s sole be presented to the systems operations team function is to recommend, organize, and aid for evaluation of feasibility and resources. For in conducting all activities which support example, appropriate members of the systems scientific research within the guidelines of the operations team will determine if there are mission objectives. The team will consist of enough consumables to support the required representatives from the various science activities and if all of the desired activity is disciplines (biology, medicine, astronomy, operationally feasible from a systems geology, atmospherics, etc.) which support standpoint. Upon verification, the proposed the science and mission objectives. Each research activity will be submitted to the crew scientific discipline will have an appropriate for execution. support team of personnel from government, An initial set of science activities will be industry, and academia who have expertise in planned before each crew departs Earth. This that field. The science operations team will act is especially true of the scientific as the decision-making body for all science investigations which support not only crew activities from determining which activities health and safety but also the primary have highest priority to handling and mission objectives. As new discoveries are disseminating scientific data. The science made and new avenues for research are operations team will be coordinated and opened, an iterative science planning process managed by the science operations manager, will become essential for the success and who will be the ultimate decision maker and effectiveness of all scientific activities.

3-121 Successful scientific operations will also resources in this program or some require, when needed, crew access to the alternative program. As many of the principal investigators for a given research benefits of an exploration program are avenue. Such access must be made feasible intangible and long term, reducing the within the structure of mission operations. program costs to an understandable and supportable level is of prime 3.9 Programmatic Issues importance.

Three significant programmatic issues •Whatever the total cost, the program will must be considered in an undertaking of this not be undertaken if resources are not magnitude, if the undertaking is to be available. Thus, cost estimates can be the successfully achieved: cost, management, basis for apportionment of resource and technology development. Each of these requirements between participants, factors was examined to determine how they phasing of resource provisions, or should be incorporated into this and further phasing of mission elements to avoid studies of the Reference Mission or peak-year funding issues that could comparable endeavors. stymie the program. Little has been done in the Reference Mission costing to 3.9.1 Cost Analysis address this question; however, the Cost analysis is an important element in database is available to analyze cost- assessing the value of a program such as this phasing strategies. and should be used from the very beginning. •The cost of mission elements and But at the beginning of a program and, in capabilities needs to be understood in many cases, up to the time that specifications order to prioritize early investments in are written and contracts are let, it is not technology and initiate other cost- possible to analytically determine the cost of a reduction strategies. The estimated cost program. If new systems need to be of each element (for example, ETO developed for programs, it is not possible to launch) is related to the program risk, know at the outset what the total cost will be with higher relative costs associated because hardware is not on the shelf. For with larger perceived risks of these reasons, cost models are used that are development or operation. Thus, typically based on historical data for similar understanding the cost can be a first step programs. in designing program risk-reduction •The total program cost will be important strategies. As part of this process, to the beneficiaries and resource estimates were also made of the cost providers, who will be interested in uncertainty for each of the technical whether to invest current and future elements of the mission, which are also

3-122 useful in understanding the appropriate program. It is also a major reason to seek capability development strategies. In the examples or benchmarks in other programs to past, technology development efforts determine the best possible management have focused primarily on improving approaches to design and development, or to performance. Now, it is important to conduct specific programs under new address reduction of cost as a goal of the management rules as prototypes for the technology development program. approach that will be used in the actual program. The cost of a program such as the Reference Mission is a function of two major The cost of doing space missions lies at variables: the manner in which it is organized the extreme edge of costliness in comparison and managed and the technical content of the to other high technology systems. The program. technical reasons for this appear to be that space missions: 3.9.1.1 Organizational Culture and Cost •Are usually one of a kind or are projects Management systems and the with small numbers of production units organization under which programs are •Are typically aimed at expanding conducted are a major factor in the cost of a capability and technology, so are program. Basing costs simply on historical designed with small margins of mass, data implies that the management system power, volume, etc. under which the historical programs were carried out will be assumed for the new •Have high transportation costs, so high program. This is a particularly serious reliability in the spacecraft is important problem in estimating the Reference Mission •Are expected to operate for extended costs, as the environment in which future periods of time in difficult environments space exploration will be carried out will be and, in the case of crewed vehicles, they much more cost-conscious than in the past. must meet high standards of safety Changes in management, for which no comparative costs are available, will have to The engineering and management occur. Because management style and culture culture that has been built up around these are introduced at each level of design and characteristics has stressed excellence of production, the leverage of management performance, safety, and high reliability. Cost changes in making cost reductions can be has typically been a secondary criterion. It is quite high. However, such changes are not clear that high quality performance and difficult to estimate. This is a major reason high reliability always require the why cost analysis should be considered a corresponding costly culture. design tool to be used at all stages of a

3-123 To illustrate the effect of culture on cost, (Cyr, 1988). This model considers the scale consider Figure 3-41 which shows the relative (particularly mass), the scope (number of cost of programs developed using different production and test articles) of the management approaches. Point 0 is the development of each of the systems required relative cost for human spacecraft, point 1 is to undertake the program, the complexity or for robotic spacecraft, point 2 for missiles, and technical readiness for each of the systems point 3 for military aircraft. Differences in and their subsystems, the schedule under management styles develop as a result of the which the program will be carried out, and different environments in which programs are the production generation in which the item carried out. is produced. To the extent that experience exists or off-the-shelf hardware can be Table 3-24 depicts the differences procured, more precise numbers can be between a “Skunk Works” management estimated. The newer or more untried a environment, such as might be used on a technology is, the greater will be its cost in the military aircraft development program (point model. 2 in Figure 3-41) and the environment for NASA’s human programs. Some of these Input for the AMCM model was derived differences will have to be addressed if the from previous experience and information cost of human space exploration is to be provided by members of the Study Team. reduced. To further illustrate differences, Included in the estimate were the Table 3-25 compares the parameters of the development and production costs for all of development culture for commercial aircraft the systems needed to support three human and NASA human programs. These are crews as they explore Mars. In addition, starting points that indicate the changes that ground rules and assumptions were adopted will be necessary. that incorporated some new management paradigms, as discussed later in the Program The cost model used for the Reference Management and Organization section. The Mission (see next section) takes these management costs captured program level variables into account in a “culture” variable, management, integration, and a Level II which can be characterized in more detail by function. Typical pre-production costs, such such attributes as organizational structure, as Phase A and B studies, were also included. procurement approach, and the degree of program office involvement in production. Not included in the cost estimate were selected hardware elements, operations, and 3.9.1.2 The Cost Model management reserve. Hardware costs not The cost model used for the technical estimated include science equipment and EVA content of the Reference Mission is the systems, for which data were not available at Advanced Missions Cost Model (AMCM) the time estimates were prepared; however,

3-124 Figure 3-41 The relative cost of programs using different management approaches. these are not expected to add significantly to When compared to earlier estimates of a the total. No robotic precursor missions are similar scale (NASA, 1989), the cost for the included in the cost estimate although their Reference Mission is approximately an order need is acknowledged as part of the overall of magnitude lower. A distribution of these approach to the Reference Mission. costs is shown in Figure 3-42. It can be seen Operations costs have historically been as from this figure that the major cost drivers are high as 20 percent of the development cost. those associated with the transportation However, due to the extended operational elements: the ETO launch vehicles, the TMI period of the Reference Mission and the stages, and the Earth-return systems. In recognized need for new approaches to addition, the organization mechanisms managing and running this type of program, chosen have significantly reduced the cost for estimating the cost for this phase of the these elements of cost, when compared to progam was deferred until an approach is traditional programs of this type, creating a better defined. Similarly, the issue of significant challenge for those who would management reserve was not addressed until manage this program. a better understanding of the management The Mars Study Team recognizes that, approach and controls has been developed. even with a significant reduction in the program cost achieved by this team, the

3-125 Table 3-24 Program Environment Effects on Program Management Style

NASA Human Program Environment Factor "Skunk Works" Management Management

Political Environment - Major threat perceived by all - Non-urgent involved - Threat not perceived as critical

Cost of Failure - Hidden - Public - Potentially catastrophic to Agency Products - High technology - High technology - Prototypes - High quality "mature" designs - Experimental Risk to Life - Acceptable, but - Unacceptable - Worthy of spending major resources - Worthy of spending major to avoid resources to avoid Public Perception - Secret - Public - Defense - Science, exploration - Urgent - Discretionary - Unaware of existence until after - Every detail open to public deployment scrutiny and criticism

Schedule - Typically 2 years - Typically 8 to 10 years Quantities - Small to moderate - Small to moderate Management Teams - Very small (under 10) - Moderate to large (dozens) • Contractor - Very small (3 to 10 typically) - Large (hundreds) • Government Political Support - High - High Cost - Small portion of parent agency - High percentage of parent budget agency budget - Low specific cost (e.g., $/1b) - High specific cost

3-126 Table 3-25 A Comparison of Development Culture Parameters for Commercial Aircraft and NASA Manned Programs

Parameter Commercial Aircraft Program NASA Human Program Management

Customer Role Requirements definition, arms Highly interactive length Detailed build specifications, some to Type of Requirements Performance of the product piece part level

Small (tens or less) Program Office Size and Large (hundreds) Interaction for clarification of Type of Interactions Interaction to lowest WBS levels details

Proximity of Program Office Geographic separation, frequent Geographic separation, with frequent Relative to Customer travel by very small groups travel for face-to-face meetings by large numbers of project people Commitment to fixed price by Three phases: end of preliminary Competition Through supplier design, program definition, start of detailed design and development Totally demonstrated flight Proof of concept Technology Status at Full systems Scale Development Start

Supplier's systems only: Management Systems Customer imposed, often duplicative occasional tailored reports to the with contractor systems customer Length of Full Scale 2 to 3 years 6 to 15 years Development Budget Strategy Full commitment with guarantees Annual, incremental, high risk by both parties Changes None to very few Thousands per year Fixed, and/or award, based on Fee Type Included in fixed price supplier performance Contract Type Fixed price with incentives Cost plus fixed, award fee

SR&QA Customer specified Industry and supplier standards

3-127 magnitude is probably still too high in today’s carried out using two HLLV launches fiscal environment. More work to further per opportunity (requires some reduce these costs is needed. reduction of capability) (Zubrin, et al., 1991). Reducing the number of launches The largest cost element of the Reference from 12 to 8 would reduce the Mission is the ETO transportation system production costs by one-third and would which makes up approximately 32 percent of reduce total costs of this element by 26 the total program cost. This element was percent. Developments in new materials, assumed to be a new HLLV capable of lifting which are rapidly occurring, could 220 tonnes of payload to LEO. Although this improve systems performance and is a launch vehicle larger than any previously reduce the mass of the protective shells developed, its design was assumed to be and vehicle systems. based on the Saturn V technology, and engines were selected from existing designs. •Reduce the size of the HLLV (also The costs of development were approximately proposed by Zubrin). This might or 20 percent of the total ETO Line Item, and might not reduce total costs, because production costs (assuming that 12 HLLVs additional costs for on-orbit operations would be produced to support the program, might be required. Reducing the cost of using 3 HLLVs for the first opportunity and 3 launch to LEO using reusable vehicles HLLV launches at each of the remaining 3 currently under consideration in the launch opportunities) were 80 percent of the reusable launch vehicle program would ETO Line Item. require very large investments in LEO assembly. The trade-off might be To reduce the cost of the HLLV favorable, but may or may not make a component, several possible strategies could significant reduction in total cost. The be used. availability and use of an in-orbit •Reduce the mass of systems, assembly capability like the International infrastructure, and payloads that need to Space Station could make this an be launched into Earth orbit for effective strategy. transport to Mars to support the surface •Improve the production efficiency for mission (assume that mission capability HLLVs. The AMCM model includes a is not going to be reduced, which is also learning curve assumption that each possible but not desirable). This could time the number of items produced reduce the total number of HLLV doubles, the cost per item is 78 percent launches and the assumed production of the previous production cost. More cost. For example, Robert Zubrin production learning could be very believes that the program could be

3-128 TMI Stage Habitation 16% 14% R&D Resources 2% 2%

Space Transport 22%

ETO 32% Surface Systems CoF 11% 1%

Figure 3-42 A comparison of the relative costs for Reference Mission elements.

significant. For example, if 12 HLLVs of conventional manner; however, some equal capability had been produced for procurement aspects were assumed to be another program, the cost of HLLVs for new, and credit was taken in the the Mars program could be cut by 22 estimates for these new ways of doing percent. To achieve these cost reductions business. The HLLV might be developed would require that no special by industry at lower cost, to meet modifications be necessary for the ETO performance specifications rather than vehicles used by the Mars program. government technical specifications. The assured sale of 12 vehicles may be large •A significant reduction in HLLV cost enough to achieve some amount of cost might be designed in at the start if new reduction to LEO, but is not likely to techniques for manufacturing and lead to major cost reductions. However, testing were introduced. However, the industry might be able to consider the learning curve benefits of mass government an “anchor tenant” for production might be less. HLLV production, develop additional •The HLLV development was assumed to markets for their technology, and be purchased by the government in a amortize the investment over a larger

3-129 number of vehicles. This would imply an included). The TMI stage was costed assumption that the space frontier is separately because it was assumed to require expanding significantly. separate development of a nuclear thermal propulsion system. The TMI stage was •The HLLV could be supplied by the assumed to be jettisoned before reaching Russians or as a joint effort by multiple Mars. Conventional space storable chemical international partners. This might be a propellants were assumed to be used in the contribution to an international program ERV stage to return to Earth. The nuclear where it would be an example of cost- thermal stage assumed considerable sharing between partners. At the present inheritance from the U. S. nuclear propulsion time, this does not appear to be a feasible program that produced the NERVA engines in solution; however, it may be reasonable the 1960s; development costs for the TMI in 15 years. If the U. S. or other partners stage were projected to be 16 percent of the were expected to pay the Russians for total cost. The space transportation vehicles their participation, it would require the are all new and include several vehicles appropriate political rationale. If the (ascent vehicle, crew capsule, and the TEI Russians were to contribute the HLLV stage). The cost of the space transportation without payment, it would be the vehicles comprises 22 percent of the total. equivalent of one-fourth of the total program cost, though it might not cost The ratio of development cost to the Russians as much as it would cost production cost for these vehicles is rather the U. S. in absolute dollars. high, partly because of the smaller number of vehicles produced for the return home. •Finally, innovative advances in Various ways of reducing the costs of these propulsion could result in the elements might be considered. development of new propulsion techniques; for example, electromagnetic •Development of nuclear electric or solar propulsion for ETO could substantially electric propulsion vehicles that are more decrease the transportation cost for some efficient could lower transportation costs materials (propellant). for cargo but might not reduce costs of human flights and might increase costs if The Earth-Mars vehicle (the TMI stage) parallel development of two and the Mars-Earth vehicle (the ERV) transportation systems was necessary. If elements provide for the delivery of humans a single technology with higher and payloads to Mars and the return of efficiency than chemical rockets could be humans to Earth. The costs are for the used to go to Mars and return, much of transportation elements alone (the the cost associated with developing the interplanetary habitat elements are not space transportation stages might be

3-130 saved because the number of separate habitats is development, production is the developments would be minimized. remaining two-thirds. Thus, cost reductions involving the improvement of design and •Systematic application of new procurement processes are potentially the techniques of automated design to the most important objectives. Note, however, development process and use of that the habitats are also a significant mass concurrent engineering could reduce life element; therefore, technology that reduces cycle costs of the systems. their mass will also have a significant effect •General improvements in methods of on the transportation system. procurement and program management Surface systems, including mobility could have significant returns in these systems and resource utilization systems, areas. Reduction of integration costs can surface power, and other nonhabitat systems, be accomplished by centrally locating constitute about 11 percent of the total design and development teams and mission cost. Because these surface systems keeping simple interfaces between are rather complex, critically determine systems manufactured by different mission productivity, and are a small fraction providers. of the total, this area does not appear to be a •Several vehicle elements could be high-priority source of major additional cost provided by international partners. Each reductions. However, mass reductions in the of the vehicles provided without cost to hardware will have high leverage in the space the program could reduce total program transportation cost elements, if the size of the costs by several percent. transportation vehicles or the number of Habitats are an essential part of the launches can be reduced. Surface systems Reference Mission scenario. They represent 14 costs are probably underestimated in the percent of total mission cost and are assumed current model, because no data for a closed to have inheritance from the International LSS, EVA hardware, and science hardware Space Station program. The Reference were included in this estimate. Development Mission has made the assumption that all of a suitable EVA suit will be a significant habitats required by the program are technology challenge and potentially essentially identical, which is probably an expensive. The closed environment LSS oversimplification. To the extent the design of hardware probably is not extraordinarily space habitats and surface habitats diverges, expensive. However, testing and the cost could rise. Eight production habitats demonstrating it will only partially occur in are required. Modest learning curve cost the International Space Station program, so reductions are assumed for the production additional cost and risk are involved in its line. About one-third of the estimated cost of development. Science equipment is not a

3-131 major cost item, in comparison with the large the expectation that optimizing the surface costs ascribed to the transportation system. mission for its benefit is also the way to improve the benefit/cost ratio for the human Operations was not included as part of exploration of Mars. the cost analysis, but has been previously estimated as a proportion (historically as high The question of management style must as 20 percent) of the total development costs. now be addressed. Particular attention needs The operations costs are incurred primarily in to be paid to the process by which the the 11 years of the operational missions. The production elements are procured. The allocation of budget that would be associated current estimates probably are still influenced with this estimate is equivalent to by current ways of doing business. If total approximately 20,000 people per year for that Reference Mission costs are to be reduced, it is period of time. This is definitely an old way of at this level of effort that the most effective doing business which must change for the changes can be made. Focusing on the wrap Mars missions. A reasonable target would be factors may not accomplish significant an operational team of approximately l,000 additional reductions, although reducing the persons. This is likely to be attainable in part production costs will also reduce the amount because automation and autonomy will be a that must be spent in these areas. necessary characteristic of the Mars missions. A principal mechanism for reducing these 3.9.2 Management and Organizational costs may be a directed program to reduce the Structure operational costs of the International Space Organization and management is one of Station as an analog to Mars missions. the principal determinants of program cost. The number and type of systems This is a rather wide-ranging topic, which is represented in the Reference Mission is near not entirely divisible from the technical minimal considering the desired surface content of the program, because it includes mission capability. It is always possible to program level decision making that is reduce costs by reducing the required intimately tied to the system engineering performance. For example, using the same decision-making process. assumptions used for this model if only a The magnitude of the Reference Mission, single landing were carried out, the total once it has been initiated, is enormous. Many program costs would be reduced by about 30 good examples exist of smaller programs that percent in comparison to the full three piloted have failed or have not performed well due to mission program. Reducing the scope of the management deficiencies. Thus, as the surface activity will not have a big effect on Reference Mission is examined and improved, cost, as it is already a relatively small continued consideration should be given to proportion of total mission costs, confirming streamlining its management; assigning

3-132 authority, responsibility, and accountability at •The human exploration of Mars will be the right levels; and developing processes that highly visible to the world, will be a tool are simple, with clear-cut interfaces and of international policy in many measurable performance standards. countries, will be complex and expensive, and will take several years to The relationship between cost and develop. Under these conditions, it is management style and organizational culture essential that a philosophical and is rather well-known in a general manner, budgetary agreement be reached prior to through a large number of lessons learned initiating development. A formal analyses made postprogram. The list of key agreement should be reached between elements of lower-cost programs is shown in all parties as to the objectives and Table 3-26. These have been pointed out in a requirements that are imposed on the series of analyses, but have not commonly mission before development is initiated, been applied at the critical stage of and an agreement to fund the project to developing program organization and its completion should be reached prior to management approaches. Rather, the development. In the U. S., this would organizational and management style has include multiyear budgetary authority. been determined rather late in the program, This should be accompanied by a generally because the program content and management process that would protect final design were typically delayed through against program overruns through redesign, changing requirements, and appropriate incentives. funding irregularities. •The human exploration of Mars will To manage a Mars program to a lowest have quite different risks than any space possible cost, a number of considerations mission which will have been have been identified. undertaken at its time. These include •The design of the organization and risks to the safety of the crew and management system should be an area accomplishment of the mission of investigation in subsequent studies of (primarily technical risks) and risks of the Reference Mission. The relationship meeting cost and schedule objectives. between program cost and program Maintaining launch schedule is culture is illustrated in Figure 3-46. exceedingly important, due to the Although several factors are involved, dependency on several successful this figure indicates that significant cost launches for mission success and the impacts are tied to the organizational high cost of missed launch windows culture and the management system. (missed launch windows imply 2-year program delays at potentially high

3-133 Table 3-26 Key Elements of Lower-Cost Programs

• Use government to define only requirements • Keep requirements fixed; once requirements are stated, only relax them; never add new ones • Place product responsibility in a competitive private sector • Specify end results (performance) of products, not how to achieve the results • Minimize government involvement (small program office) • Ensure that all technologies are proven prior to the end of competition • Use the private sector reporting reporting system: reduce or eliminate specific government reports • Don't start a program until cost estimate and budget availability match • Reduce development time: any program development can be accomplished in 3 to 4 years once uncertainties are resolved • Force people off development programs when development is complete • Incentivize the contractor to keep costs low (as opposed to CPAF, CPFF, or NASA) • Use goegraphic proximity of contractor organizations when possible • Use the major prime contractor as the integrating contractor

program cost). Thus a risk management control for the program. To accomplish plan can help identify the risks and this: formulate a mitigation strategy. -There should be a clear demarcation •The Reference Mission requires a between the design phase and the number of elements, many of which are development/production phase of the technically alike but serve somewhat project, and development should not different functions over the duration of begin before the design phase is ended. the program. For example, the surface -All technologies should be proved prior habitat may be the basis for the transit to initiation of production of program habitat, and each habitat delivered to the elements. surface will have a different complement of equipment and supplies, according to -Once the requirements have been its position in the delivery sequence. The established, they should not be changed elements will be developed over a unless they can be relaxed. period of several years, and there will be -A system should be developed that a temptation to improve the equipment documents the relationship and and supply manifest. It will be important interaction of all requirements and for requirements to be fixed at the time should be available for use prior to the of initial development to maintain cost beginning of production.

3-134 •The design phase of the program is there may be a high enough production critical to successful cost control. The rate that costs will drop as experience is design should be based on a set of gained. A new approach will be needed functional requirements established by a to ensure that the development time for Program Office, which may well be a each individual element is strictly multinational activity. The Program limited. Office should be in place to manage •The program will require two levels of technical requirements, provide integration, similar to that of the decisions that require consultation and International Space Station program: a trade-offs (technical and political), and program level which ensures that overall manage development contracts. The mission requirements will be met at each Program Office should also establish stage of the mission, and a launch functional requirements for the design package level integration in which all phase and conduct a competitive required elements of each launch to procurement for the design phase with Mars are packaged and their the selection of a prime contractor. To performance ensured. To accomplish accomplish this: this, both aspects of integration should -Requirements should be provided for the be the responsibility of a single design phase, describing the organization, a prime contractor to the performance expected, and a clear set of Program Office. criteria for completeness of design as a •The operational phase of the Mars function of resources expended in program must be represented in the design. design and development phase. This will -A significant design cost margin should require a concurrent engineering be used to manage the design resources. approach which considers the operational costs as well as the -The successful prime contractor should development costs in a life cycle cost be selected as integration contractor for approach to the program. To accomplish the development phase. this, operational considerations must be •Once committed to development, the included in the design and development development time should be strictly phases of the program, and life cycle limited if costs are to be contained. This costs should be used as the determinant will be difficult in the Mars program, for program design and development where it probably will be effective to decisions. produce common elements sequentially rather than all at one time, although

3-135 •Finally, at all stages of design, the effort to bring the original technology to development, production, and its desired state. operations, all program office officials At this particular stage in developing and contractor organizations must be human exploration missions to Mars, it is incentivized to maintain program costs difficult to do more than speculate about spin within approved levels, and positive off and spill over technologies that could incentives must be put into place to result from, or be useful to, this endeavor. reduce costs of each phase of the However, identifying dual uses for some of program. the assumed technologies can be started now and, to a certain degree, will be required for 3.9.3 Technology Development such a program to progress. In the current The Reference Mission was developed political environment, investment in with advances assumed in certain technology technology is seen as a means of improving areas known to be necessary to send people to the general quality of life, and multiple use of Mars for a reasonable investment in time and technologies is emphasized to obtain the best resources. The same objective could be return on the resources invested in their satisfied using other technologies in some development. Space programs are not spared cases, making it necessary to identify this requirement. A program strategy that selection criteria for the set of technologies the emphasizes dual-use technologies, besides Reference Mission should favor. A reasonable being consistent with this current trend could: investment also implies that there must be •More easily generate funds through some reliance on technologies developed for increased cooperation and joint ventures other uses or simply discovered during some with other U.S. federal agencies, other development activity. international partners, and commercial Dual-use technologies are those which concerns are deliberately developed with more than •Provide smaller projects which could be one application in mind and which carry more easily funded requirements for these various uses through the development period. Spin off or spin in •Provide a step-by-step approach to the technologies are those which are developed Reference Mission with a specific application in mind but which •Provide a stimulus to local and national find other uses with little or no additional economies development work. Spill over technologies are those which grow to include entirely new, •Foster an increase in advocacy for space unplanned technologies as a by-product of programs

3-136 To this end, the Reference Mission study NASA and the Department of Energy to identified and worked with 10 Mars mission- develop small nuclear power sources for related technology categories: propulsion, robotic spacecraft could be expanded to communications and information systems, include the development of larger power ISRU, surface mobility - suits, surface sources (perhaps as part of a cooperative mobility - vehicles, human support, power, endeavor with the Russian government) or structures and materials, science and science for the propulsion system technologies equipment, and operations and maintenance. assumed for the Reference Mission. The These categories were then associated with a Department of Defense is currently studying total of 54 technology areas along with their an integrated propulsion and electrical power applications. Tables 3-27 through 3-36 system driven by the heat of the Sun document these various technology (Reference: Anon., 1995). This could be a applications. In addition, the tables indicate technology useful to the Reference Mission as where these technologies may spin off into an alternative to the nuclear system assumed other applications and where developments and form the basis for a cooperative in other areas may, in fact, benefit or spin into development program. the Mars program. Several specific examples may help Not all of the advantageous technology illustrate how technology development for for the Reference Mission must be developed the Reference Mission will benefit from spill by the program organization. International over, spin off, and dual-usage. cooperation can benefit from the technology One of the precursor activities to the advancements needed for this class of space Reference Mission that has a high priority will mission. Two obvious examples include be the characterization of the martian surface heavy lift launch technology and space-based in great detail by orbiting robotic spacecraft. nuclear power. The relatively heavy lift Data collected by this vehicle or vehicles will launch capabilities either developed or be needed in many areas to prepare for this nearing completion for the Russian Energia Reference Mission. One of the most and the European Ariane V could form the significant areas will be the choice of a basis for at least part of a cooperative landing site at which the outpost will be technology development program. The established. This selection will be based in former Soviet Union had also developed a part on information ranging from hazards in relatively sophisticated operational space- the proposed landing zone to the proximity of based nuclear power capability. the site to a variety of surface features, the U.S. federal agencies can also cooperate investigation of which will contribute to to develop mutually beneficial technologies. meeting the overall Reference Mission The long-standing cooperation between objectives. Technology to obtain this remote

3-137 sensing data could be available from the U.S., •The Russian Energia heavy lift launch Russia, Japan, and the Europeans, based on system can be maintained and upgraded their previous Earth-orbiting, remote-sensing until human missions to Mars can begin. missions and other planetary explorations. A variation of this would be to evolve a But due to the high cost of transporting these higher capacity launch vehicle using sensors to the vicinity of Mars, further technologies developed for Energia, development or enhancement of these Ariane V, and the Space Shuttle. Either of technologies could reduce their size, mass, these options would offer an and need for supporting resources (power, opportunity for international communications band width, etc.). cooperation that would not only benefit Advancements in other areas, such as the Ka the Reference Mission but also allow for band utilization, data compression, and heavier, more sophisticated payloads to information processing technologies be launched into Earth orbit or used for mentioned in the Communication and lunar missions. Information Systems category or from •The mass of hardware required to technology developed as part of the explosive support humans in Mars journeys can be growth in the PC marketplace, can also serve reduced. Few concepts now exist for to improve performance and reduce costs for this, but advancements in the technology these systems and the data they return. Any options mentioned in most, if not all, of technology enhancement developed to the 10 categories identified by the Mars support the Reference Mission will then be Study Team will lead to a reduction in available for use in Earth-orbiting the hardware mass that must be sent to applications. Mars. Each of the 10 categories also The single largest cost of a human Mars identified Earth-bound applications that exploration program may be the cost of ETO may also benefit from these transportation. The development of a new advancements. HLLV solely for the Mars program could A third example involves the significant require up to 30 percent of the total resources level of automation assumed for the for the program. However, approaches that Reference Mission. The program assumes can launch the appropriate payloads to Mars infrastructure elements (including a system to using smaller launch vehicles have not produce propellant and life support appeared to be viable in the past. This is a consumables, the first of two habitats, power conundrum which has and may still stymie systems, and surface transportation elements) human exploration of Mars. Other avenues will robotically land on the surface at a exist: designated location. All of these systems will be delivered, set up, and checked out using

3-138 Table 3-27 Dual-Use Technologies: Propulsion

Terrestrial Application Technology Space Application

• Nuclear Reactors • Weapons and Nuclear Waste Disposal • NTR • High-Temp Materials • High-Efficiency Heat Engines • Aerobraking (Turbines, Thermostructural Integrity)

• High Efficiency • Propellant • Clean-Burning Engines (H /O ) 2 2 Cryo-Refrigeration Maintenance

• Methane/O Rocket • ISRU-Based Space • Higher Performance Commercial Launches 2 Engines Transportation

Table 3-28 Dual-Use Technologies: Communications/Information Systems

Terrestrial Application Technology Space Application

• Communications High-Definition • Ka Band or Higher • Telepresence: Vision and TV Broadcast Video Data • Interferometers: Raw Data Transmission • Entertainment Industry • Machine-Human Interface • Control Stations • Commercial Aviation • System Management

• Communications • Data Compression • Interferometers: Raw Data • Archiving Information Processing Transmission Information • Large Scale Data Processing Management Systems • System Management, Expert Data • Archiving/Neural Nets spin-in spin-off Both

3-139 Table 3-29 Dual-Use Technologies: In Situ Resource Utilization

Terrestrial Application Technology Space Application

• Mineral Analysis, Yield Estimation- • Advanced Sensors • Mineral Analysis, Yield Deep Mine Vein Location and Tracking Estimation Surface Mineral • Wall and Ceiling Integrity Analysis, and Resource Location • Deep Mine Robotic Operations • Advanced Robotic • Surface Mining Operations • Mining Mining • Mining • Beneficiating • Beneficiating • Removal • Removal

• Improved Automated Processing; • Automated Processing: • Remote, Low- Increased efficiency Advanced FDIR Maintenance, Processing

• Reliable, Low-Pollution Personal • Alternative, Regenerable • ISRU-Based Engines Transmission Energy Economies • Regenerable Energies

• Regenerable Energy Economies • Methane/O2 • High-Density Energy Storage

• Small, Decentralized Power Systems for • H2/O2 Remote or Third World Applications

• Environmentally Safe Energy Production • Space-Based Energy • Surface Power Generation Generation and and Beaming Transmission spin-in spin-off Both

3-140 Table 3-30 Dual-Use Technologies: Surface Mobility - Suits

Terrestrial Application Technology Space Application

• Hazardous Materials Cleanup • Lightweight, Superinsulation • Surface Suits: Thermal • Fire Fighting Protection and Materials Protection Underwater Equipment

• Robotic Assisted Systems • Robotics •Robotic Assisted Suit Systems • Orthopedic Devices for Mobility • Mobility Enhancement Devices Impaired Persons and Manipulators

• Hazardous Materials Cleanup • Dust Protection, Seals, Abrasive • Surface Suits: Outer Garment • Fire Fighting Protection and Resistant Materials Underwater Equipment

• Hazardous Materials Cleanup, • Lightweight Hi-Rel, Life Support • Portable Life Support for Surface Underwater Breathing Gear Suits

• Remote Health Monitoring • Portable Biomedical Sensors and • Surface EVA Crew Member Health Evaluation Systems Health Monitoring

• Hypo-Hyper Thermal Treatments • Small, Efficient, Portable, • Surface Suits: Thermal Control • Fire Fighting Protection and Cooling/Heating Systems Systems Underwater Equipment • Artic/Antartic Undergarments

Table 3-31 Dual-Use Technologies: Surface Mobility - Vehicles

Terrestrial Application Technology Space Application

• All-Terrain Vehicles • Mobility • Surface Transportation • Research (Volcanoes) • Humans • Oil Exploration • Science Equipment • Maintenance and Inspection

• Reactor Servicing/Hazardous • Robotics and Vision Systems • Teleoperated Robotic Systems Applications • Earth Observation, Weather, Research • Super-Pressure Balloons • Mars Global Explorations (110,000 ft - Earth Equiv)

• Efficient, Long-Term Operations • Tribology • Surface Vehicles Low-Maintenance • Drive Mechanisms • Machines in Artic/Antaric • Robotic Arms Environments • Mechanisms • Helicopers, Autos • Variable Speed Transmissions • Surface Vehicles

• Automated, Efficient Construction • Multipurpose Construction • Robotic Construction and Equipment Vehicle Systems and Mechanisms Set-up Equipment spin-in spin-off Both

3-141 Table 3-32 Dual-Use Technologies: Human Support

Terrestrial Application Technology Space Application

• Stored Food • Long-Life Food Systems • Efficient Logistics • US Army • With High Nutrition • Planetary Bases • NSF Polar Programs • Efficient Packaging • Long Spaceflights • Space Stations

• Improved Health Care • Physiological Understanding of the • Countermeasures for Long-Duration • Sports Medicine - Cardiovascular Human/Chronobiology and/or Micro-g Space Missions • Osteoporesis - Immune Systems • Understanding of Psychosocial • Health Management and Care • Isolated Confined Environments/Polar Issues Operations • Instrumentation Miniaturization • Noninvasive Health Assessments

• Health Care • Long-Term Blood Storage • Health Care for Long-Duration Space • Disaster Response Missions • US Army

• Office Buildings • Environmental Monitoring and • Environmental Control for ("Sick Building" Syndrome) Management • Spacecraft Cabins • Manufacturing Plants • Planetary Habitats • Pressurized Rovers

• Contamination Cleanup • Waste Processing/SCWO • Closed Water Cycles for • Waste Processing • Water Purification • Spacecraft Cabins • Planetary Habitats • Pressurized Rovers

• Long-Life Clothes • Advanced Materials/Fabrics • Reduced Logistics Through Long-Life, • Work Clothes in Hazardous Easy-Care Clothes, Wipes, Etc. Environments • Fire Proof/Low-Out-gassing Clothes • US Army

• Efficient Food Production • Advanced Understanding of • Reduced Logistics Through Local Food Food Production/Hydroponics Production for • Spacecraft Cabins • Planetary Habitats

Table 3-33 Dual-Use Technologies: Power

Terrestrial Application Technology Space Application

• Batteries/RFCs for • High-Density Energy Storage • Reduced Logistics for Planetary • Autos • Alternate Energy Storage Bases • Remote Operations (Flywheels) • High-Rel, Low-Maintenance • DOD Power Systems • NSF Polar Programs

• Clean Energy From Space • Beamed Power Transmission • Orbital Power to Surface Base • Surface Power Transmission to Remote Assets

• Remote Operations • Small Nuclear Power Systems • Surface Base Power • DOD •Pressurized Surface Rover • NSF Polar Programs • Interplanetary Transfer Vehicle

• Remote Operations • High-Efficiency, High-Rel, • Energy Conversion for Planetary • DOD Low-Maintenance Heat-to- Bases • NSF Poloar Programs Electric Conversion Engines • Low Servicing Hours • High-Efficiency Auto Engines • Little or no Logistics spin-in spin-off 3-142 Both Table 3-34 Dual-Use Technologies: Structures and Materials

Terrestrial Application Technology Space Application

• Vehicles • Composite Materials • Cryo Tanks • Fuel-Efficient Aircraft • Hard • Habitat Enclosures • Modular Construction (Homes, etc.) • Soft • Pressurized Rover Enclosures • Advanced Alloys, High- • Space Transit Vehicle Structures Temperature

TBD • Superinsulation • Cryo Tanks • Coatings • Habitable Volumes

• Large Structures, High-Rises, Bridges • Smart Structures • Space Transit Vehicle Structures • Commercial Aircraft • Imbedded Sensors • Planetary Habitat Enclosures • Improved Safety • Surface Power Systems • Lower Maintenance • Rover Suspensions

Table 3-35 Dual-Use Technologies: Science and Science Equipment

Terrestrial Application Technology Space Application

• Energy Resource Exploration • Spectroscopy • Geo-chem Mapping • Environmental Monitoring, Policing • Gamma Ray • Resource Yield Estimating • Laser • Planetary Mining Operation • Other Planning

• Undersea Exploration • Telescience • Remote Planetary • Hazardous Environment Assessments, Exploration Remediation

• Environmental Monitoring • Image Processing • Communication of Science • Medicine • Compression Technique Data • Storage • Correlation of • Transmission Interferometer Data • Image Enhancements

• Improved Health Care • Physiological Understanding of • Countermeasures for Long- • Sports Medicine - Cardiovascular the Human Duration and/or Micro-g • Osteoporesis - Immune Systems • Instrumentation Miniaturization Space Missions • Isolated Confined Environments/Polar • Health Management and Operations Care • Noninvasive Health Assessments

spin-in spin-off Both

3-143 Table 3-36 Dual-Use Technologies: Operations and Maintenance

Terrestrial Application Technology Space Application

• Task Partitioning • R & QA in Long-Term, Hazardous Environments • System Health Management and Failure Prevention Through A1 and Expert Systems, Neural Nets

We mentioned this area as important, but did not complete. Recommend that we work with Jon Ericson and bob Savely to get ir right.

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