Extending Human Presence into the Solar System An Independent Study for The Planetary Society on Strategy for the Proposed U.S. Space Exploration Policy July 2004 Study Team William Claybaugh Owen K. Garriott (co-Team Leader) John Garvey Michael Griffin (co-Team Leader) Thomas D. Jones Charles Kohlhase Bruce McCandless II William O’Neil Paul A. Penzo The Planetary Society**65 N. Catalina Avenue, Pasadena, CA 91106-2301**(626) 793-5100** Fax (626) 793- 5528**E-mail: [email protected]** Web: http://planetary.org Table of Contents Study Team 2 Executive Summary 4 Overview of Exploration Plan 5 Introduction 6 Approach to Human Space Flight Program Design 9 Destinations for the Space Exploration Enterprise 9 International Cooperation 13 1. Roles 13 2. Dependence on International Partners 14 3. Regulatory Concerns 15 Safety and Exploration Beyond LEO 15 The Shuttle and the International Space Station 17 Attributes of the Shuttle 17 ISS Status and Utility 18 Launch Vehicle Options 18 U.S. Expendable Launch Vehicles 19 Foreign Launch Vehicles 20 Shuttle-Derived Vehicles 21 New Heavy-Lift Launcher 21 Conclusions and Recommendations 22 Steps and Stages 22 Departing Low Earth Orbit 22 Electric Propulsion 24 Nuclear Thermal Propulsion 25 Interplanetary Cruise 27 Human Factors 27 Gravitational Acceleration 27 Radiation 28 Social and Psychological Factors 28 System Design Implications 29 The Cost of Going to Mars 30 Development Costs 30 Production Costs 30 First Mission Cost 31 Subsequent Mission Cost 31 Total 30-Year Cost 31 Sensitivity Analysis 31 Cost Summary 32 Policy Implications and Recommendations for Shuttle Retirement 32 Overview, Significant Issues, and Recommended Studies 33 References 35 The Planetary Society**65 N. Catalina Avenue, Pasadena, CA 91106-2301**(626) 793-5100** Fax (626) 793- 5528**E-mail: [email protected]** Web: http://planetary.org Executive Summary we recommend phased development of the (modified 08/17/04) new CEV, with the “Block 1” version designed for LEO access and return only, We propose here a staged approach to with a later “Block 2” version suited to the human exploration beyond low Earth orbit requirements of interplanetary missions. The (LEO). We believe such a plan must be CEV would be launched on a new human- adopted if the overall funding profile is to be rated vehicle, possibly based on the existing kept within the bounds that are likely to be Shuttle solid rocket motor (SRM), acceptable to the many future Congresses augmented with a new liquid upper stage. and Administrations that must “sign on” to Such a system could be available before the Exploration Initiative if it is to succeed. 2010. With Orbiter retired after U.S. Core Stage 1 features the development of a complete and with international agreement new crew exploration vehicle (CEV), the to proceed, any remaining assembly tasks completion of the International Space can be completed by the heavy-lift launch Station (ISS), and an early retirement of the vehicle (HLLV) that must be developed to Shuttle Orbiter. Orbiter retirement would be support later stages of the Exploration made as soon as the ISS U.S. Core is Initiative, by use of expendable launch completed (perhaps only 6 or 7 flights) and vehicles (EELVs) as appropriate, or on the smallest number of additional flights suitable international vehicles such as necessary to satisfy our international Ariane or Proton. partners’ ISS requirements. Money saved by Stages 2 and 3 of the proposed early Orbiter retirement would be used to Exploration architecture will require heavy- accelerate the CEV development schedule to lift launch capability well in excess of the minimize or eliminate any hiatus in U.S. 20–25 metric ton capacity of the present capability to reach and return from LEO. evolved EELV fleet. We believe these Stage 2 requires the development of requirements can best be met, at least additional assets, including an uprated CEV initially, by means of designs that utilize capable of extended missions of many existing Space Shuttle components (e.g., the months in interplanetary space. Habitation, SRM and External Tank). Some proposed laboratory, consumables, and propulsion Shuttle-derived HLLVs have a payload modules, to enable human flight to the capacity in excess of 100 metric tons and vicinities of the Moon and Mars, the offer a near-term approach to meeting Lagrange points, and certain near-Earth Exploration requirements with a minimum asteroids. Development of human-rated of non-recurring investment. planetary landers is completed in Stage 3, Prompt studies to confirm our allowing human missions to the surface of recommendations are needed in areas of the Moon and Mars beginning around 2020. early CEV design for Block 1 capability to The overall plan is summarized in Table 1. and from LEO, to establish the minimum A key to this vision is the requirement to number of Shuttle flights necessary to meet complete assembly of the ISS and to retire international requirements, to find the best the Shuttle Orbiter, without in the process launch vehicle for the CEV, and to perform incurring another lengthy hiatus in the trade studies for HLLV needs and ability of the United States to conduct configuration. crewed spaceflight operations. To this end, The Planetary Society**65 N. Catalina Avenue, Pasadena, CA 91106-2301**(626) 793-5100** Fax (626) 793- 5528**E-mail: [email protected]** Web: http://planetary.org Overview of Exploration Plan Stage One, access to LEO, through 2010 • Shuttle-Orbiter return to flight (RTF), complete the ISS through at least “US Core Complete” • Select and demonstrate launch vehicle for CEV • Demonstrate early CEV use for crew transfer at the ISS • Negotiate with international partners to obtain best way to transport remaining heavy modules to the ISS • Retire Orbiter as soon as above steps are completed • Costs distributed across full Exploration window Stage Two, interplanetary cruise, through 2015 and beyond • Develop interplanetary cruise capability; uprated CEV, and necessary additional modules for the destination selected • Ensure HLLV available, probably a Shuttle-derived HLLV • Enable lunar orbit missions, remote sensing, Rovers with sample return • Enable visits to Sun-Earth-Lagrange #2, astronomy, etc. • Enable visit and study of near-earth objects (NEOs) • Enable visits to Mars vicinity, including moons Phobos and Deimos. Include remote sensors and Rover with return samples. Begin infrastructure placement. Select sites. • Select destinations as appropriate: science, public, other interests Stage Three, human surface landings, 2020 and beyond • Prepare infrastructure for moon and/or Mars bases • Build on thorough preparation in preceding stages • Initiate human landings at selected destinations • Plan for future solar system exploration The Planetary Society**65 N. Catalina Avenue, Pasadena, CA 91106-2301**(626) 793-5100** Fax (626) 793- 5528**E-mail: [email protected]** Web: http://planetary.org Introduction The CEV should be designed explicitly to have sufficient on-orbit life that it can be The recent Presidential Directive to focus resident at the ISS for extended periods, thus NASA’s future on exploration via "the Moon and on to Mars" has invigorated the space community and many of the general providing the emergency crew return public. Meeting these goals while remaining capability that, at present, is available only within realistic funding expectations is via the Russian Soyuz spacecraft. The long- foreseen as the major difficulty in meeting duration requirement is an obvious necessity this challenge. The Planetary Society has in an exploration vehicle. In addition, the commissioned this Report to encourage crew-return vehicle (CRV) function requires support for this new venture and to suggest a that it be capable of remaining stable and workable strategy for human exploration of quiescent, with minimal power drain, for the solar system, with the specific goal of long periods. placing humans on the Martian surface at We believe that there are significant the earliest possible moment, while allowing advantages, both for the United States and costs to be managed at reasonable levels. for the ISS partners, associated with It will be suggested below that the developing the new LEO transportation exploration can be conducted in three stages. capability as early as possible. All partners Stage 1 is the early development of a new would benefit from an earlier beginning of Crew Exploration Vehicle (CEV), as the the benefits of having larger multinational President has directed, accompanied by the crews on the ISS. The remaining heavy development of a launch vehicle to transport modules for the ISS might be better the CEV to and from low Earth orbit (LEO). transported to the ISS by means of a Shuttle- Success with the CEV will lead to missions derived HLLV, to be discussed below. It beyond LEO. We are recommending that should again be emphasized that the strong consideration be given to a specific proposed early development of a new LEO design using the Shuttle solid rocket motor transport system is intended to achieve (SRM), together with a new liquid earlier and more frequent access to the ISS propellant upper stage, for this role. We for all partners. The Orbiter would then be believe that this evolutionary development retired promptly to save the high costs of will be the quickest and least expensive path maintaining Orbiter operations, with the cost to realizing a U.S. capability to send humans savings making funds available for Stages 2 to LEO, and beyond, without the use of the and 3. The ISS can be used not only by our Shuttle Orbiter. This capability should be international partners but also by U.S. crews available well before 2010, the date by for tasks associated with solar system which the Orbiter is to be retired. By this exploration, including qualifying personnel time, the International Space Station (ISS) for long-duration missions and for studying should have reached at least the “U.S.