Humans to Mars: Fifty Years of Mission Planning, 1950-2000

The Living and Working on Mars group looked at chores the crew would need to perform during their Mars stay. These included initial base setup, such as deploying an inflatable greenhouse, and base maintenance, such as ridding air filters of ever-present ultra-fine Martian dust. Astronauts on Mars would also harvest crops, service their space suits, and perform less mundane tasks such as exploring the surface in the pressurized rover and drilling deep in search of Martian microorganisms that might hide far beneath the surface.

The workshop recommended that "a process and program be put into place whereby a wide range of people could contribute to the thought process." The report urged that students in particular be involved, because "their representatives will be the ones who are actually to do this exploration." 33

A New Concept

Meanwhile, engineers at NASA Lewis studied using solar-electric propulsion in the DRM to further reduce the amount of weight that would have to be launched into orbit. In January 1999, they proposed a novel concept using a Solar-Electric Transfer Vehicle (SETV) which never left Earth orbit, but which provided most of the energy needed to launch the Mars vehicles from Earth orbit toward Mars. 34

The 1997 DRM required eight Shuttle-derived rockets for the first Mars expedition. By contrast, the Lewis solar-electric DRM required only five rockets. Removal of the backup Habitat lander—a decision taken by Mars planners in the JSC Exploration Program Office—eliminated two heavy-lift rockets. Replacing the four nuclear stages used to leave Earth in the 1993 and 1997 DRMs with the SETV and three small expendable chemical stages eliminated one more. This substitution also eliminated the cost of developing a nuclear rocket engine and the potential political headaches of launching nuclear payloads.

The Lewis team envisioned a self-erecting SETV weighing 123 tons and measuring 194.6 meters across its thin-film solar arrays. The arrays would provide electricity to two sets of Stationary Plasma Thrusters (SPTs), also known as TAL (Thruster with Anode Layer) or Hall thrusters, an electric propulsion technology pioneered by the Russians.

The SETV would need months to complete large orbit changes. Because of this, it would spend considerable time crossing through Earth's Van Allen Radiation Belts. This meant that the Lewis DRM vehicles would require radiation-hardened systems. The authors assumed that the SETV would be good for two missions beyond the Van Allen belts before radiation, temperature extremes, meteoroid impacts, and ultraviolet light seriously degraded its solar arrays.

Figure 30—In 1998, NASA Lewis Research Center proposed a reusable Solar-Electric Transfer Vehicle (SETV) and clever use of orbital mechanics to reduce Mars expedition mass. SETV's solar panel spars would inflate in orbit, spreading "wings" of solar cell fabric. (NASA Photo S99-03585)

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The SETV's first mission would place one unpiloted cargo vehicle and one unpiloted ERV, each with a small chemical rocket stage, into High-Energy Elliptical Parking Orbit (HEEPO) around the Earth. The SETV would start in a nearly circular low-Earth orbit and raise its apogee by operating its SPT thrusters only at perigee. It would need from six to twelve months to raise its apogee to the proper HEEPO for Earth-Mars transfer. The final HEEPO apogee would be more than 40,000 kilometers, making it very lightly bound by Earth's gravity.

When Earth, Mars, and the plane of the HEEPO were properly aligned for Earth-Mars crossing, the SETV would release the cargo lander, ERV, and small chemical stages. At next perigee the chemical stages would ignite, pushing the spacecraft out of the HEEPO on a path that would intersect Mars six months later. After releasing the chemical stages and spacecraft, the SETV would point its SPTs in its direction of motion and operate them at perigee to return to a circular low-Earth orbit.

The SETV's second mission would place one Habitat lander with a small chemical stage into HEEPO. Because the climb to HEEPO again would require up to twelve months and long periods inside the Van Allen Radiation Belts, the Habitat lander would remain unpiloted until just before Earth orbit departure. As the SETV climbed toward planned final HEEPO apogee, a small, chemical-propellant "taxi" carrying the Mars crew would set out in pursuit. The crew would transfer to the Habitat lander, cast off the taxi, then separate the Habitat lander and chemical stage from the SETV. At the next perigee, the chemical stage would ignite to place the first expedition crew on course for Mars. The remainder of the first Mars expedition would occur as described in the 1997 scrubbed DRM, except for the absence of a backup Habitat lander.

In February 1999, soon after the Lewis team made public their variation on the 1997 DRM, Mars Global Surveyor achieved its nominal mapping orbit. At this writing, exploration and data interpretation are ongoing, but it is already clear that the spacecraft is revolutionizing our understanding of Mars. By mid-2000, its instruments had detected evidence that Mars once had a strong planetary magnetic field, a finding potentially important for the early development of Martian life; that Mars' polar regions once knew extensive glaciers; and that water flowed on Mars' surface recently, and perhaps flows occasionally today, carving gullies in cliffs and crater walls.

Not the Last Chapter

In May 1998, a small team of NASA and contractor space suit engineers traveled to sites in northern Arizona where Apollo Moonwalkers had trained three decades before. They observed and assisted as a veteran geologist wearing a space suit performed geological field work and set out simulated scientific instruments in Mars-type settings—for example, on the rim of Meteor Crater. The team contained cost by traveling from Houston to Arizona overland and by reusing a space suit originally designed for Space Station Freedom. In addition to gathering data on space suit mobility to enable design of future Mars space suits, the exercise permitted veteran space suit engineers who had participated in the development of the Apollo lunar space suits to pass on their experience to young engineers who had been children, or not yet born, when Americans last walked on an alien world. 35

Michael Duke and the other organizers of the Human Exploration and Development of Space-University Partners (HEDS-UP) program had a similar motive. They sought to involve and inspire the next generation of Mars planners, who might become the first generation of Mars explorers. In May 1998, the first HEDS-UP Annual Forum saw undergraduate and graduate design teams from seven universities across the United States present Mars design studies. 36 Twice as many universities sent enthusiastic students to the 1999 HEDS-UP Annual Forum. 37

In the nearly half-century since von Braun wowed Americans with visions of Mars flight in Collier's magazine, our understanding of Mars has steadily improved. We have progressed from hazy telescopic views of Mars to pictures on the Internet of Sojourner rearing up on a flood-tossed Martian boulder. Plans for piloted Mars exploration have matured in step with our improved vision. For example, no longer do planners seek to bring all necessities from Earth, for now it is known that Mars has useful resources.

The Mars planning concepts developed in the twilight years of the second millennium form a launch pad for Mars planners—and perhaps Mars explorers—at the dawn of the third. Current technological trends—for example, increasingly capable miniaturized robots and direct public engagement in Mars exploration through the Internet—promise to reshape Mars planning.

Yet it should be remembered that ISRU, the concept that dominated Mars planning in the 1990s, dates from the 1960s and 1970s. This suggests that, in addition to whatever new revolutions future technological development brings, other revolutions might lie buried in the historical archives awaiting the careful and imaginative researcher. Further, this suggests that Mars planners should carefully preserve their work lest they deprive future planners of useful concepts.

Young people now looking to Mars, such as the student participants in the HEDS-UP program, should not have to waste their time reinventing old concepts. They should instead be able to study the old concepts and build new ones upon them. They should also be able to study the political and social settings of the old concepts, so that they might better navigate the "illogical" pitfalls that can bring down a technically logical Mars plan. Providing the next generation with the history of Mars planning helps hasten the day when humans will leave bootprints on the dusty red dunes of Mars.

Acronyms

Endnotes

Preface

• 1. Edward Ezell, "Man on Mars: The Mission That NASA Did Not Fly" (paper presented at the American Association for the Advancement of Science Annual Meeting, Houston, Texas, 3-8 January 1979), p. 24.
• 2. Readers seeking additional information on Mars planning are directed to the author's Web site Romance to Reality (http://members.aol.com/dsfportree/explore.htm), which contains over 250 annotations of Moon and Mars planning documents, with more added regularly.

Chapter 1

• 1. Wernher von Braun with Cornelius Ryan, “Can We Get to Mars?” Collier’s (30 April 1954), p. 23.
• 2. Frederick Ordway and Mitchell Sharpe, The Rocket Team (New York: Thomas Y. Crowell, 1979), p. 408.
• 3. Wernher von Braun, The Mars Project (Urbana, IL: University of Illinois Press, 1962).
• 4. Ibid., p. 3.
• 5. Ibid., p. 75.
• 6. Louise Crossley, Explore Antarctica (Cambridge, England: Cambridge University Press, 1995), p. 40.
• 7. Fred Whipple and Wernher von Braun, "Man on the Moon: The Exploration," Collier's (25 October 1952), p. 44.
• 8. Wernher von Braun, “Crossing the Last Frontier,” Collier’s (22 March 1952): 24-29, 72.
• 9. Wernher von Braun, "Man on the Moon: The Journey," Collier's (18 October 1952): 52-60; Whipple and von Braun, "Man on the Moon: The Exploration," pp. 38-48.
• 10. Von Braun with Ryan, “Can We Get to Mars?” pp. 22-28.
• 11. Ibid., pp. 26-27.
• 12. Willy Ley and Wernher von Braun, The Exploration of Mars (New York: Viking Press, 1956).
• 13. Ibid., p. 85.
• 14. Ibid., p. 98.
• 15. Ibid., p. 157.

Chapter 2

• 1. John F. Kennedy, "Excerpts from 'Urgent National Needs,' " Speech to a Joint Session of Congress, 25 May 1961, in John Logsdon, gen. ed., with Linda Lear, Janelle Warren-Findlay, Ray Williamson, and Dwayne Day, Exploring the Unknown: Selected Documents in the History of the U.S. Civil Space Program, Volume I: Organizing for Exploration (Washington, DC: NASA SP-4407, 1995), pp. 453-54.
• 2. Robert Merrifield, "A Historical Note on the Genesis of Manned Interplanetary Flight," AAS Preprint 69501 (paper presented at the AAS 15th Annual Meeting, 17-20 June 1969), p. 7.
• 3. David S. F. Portree, NASA's Origins and the Dawn of the Space Age (Washington, DC: NASA Monographs in Aerospace History #10, 1998), pp. 8-11.
• 4. Ezell, “Man on Mars,” pp. 5-6; see also Merrifield, “A Historical Note,” p. 8.
• 5. S. C. Himmel, J. F. Dugan, R. W. Luidens, and R. J. Weber, "A Study of Manned Nuclear-Rocket Missions to Mars," IAS Paper No. 61-49 (paper presented at the 29th Annual Meeting of the Institute of Aerospace Sciences, 23-25 January 1961), p. 2.
• 6. Ibid., p. 5.
• 7. Ibid., p. 18.
• 8. Von Braun with Ryan, “Can We Get to Mars?” p. 24.
• 9. Himmel, et al., “A Study of Manned Nuclear-Rocket Missions to Mars,” p. 35.
• 10. Ibid., p. 24.
• 11. Ibid., p. 30.
• 12. Ibid., p. 33-34.
• 13. John Logsdon, The Decision to Go to the Moon: Project Apollo and the National Interest (Cambridge, MA: MIT Press, 1970), pp. 111-12.
• 14. Office of Program Planning and Evaluation, "The Long Range Plan of the National Aeronautics and Space Administration," 16 December 1959, Logsdon, gen. ed., Exploring the Unknown, Vol. I, p. 404.
• 15. Ezell, “Man on Mars,” p. 8.
• 16. Ernst Stuhlinger, "Possibilities of Electrical Space Ship Propulsion," Friedrich Hecht, editor, Bericht über de V Internationalen Astronautischen Kongress (Osterreichen Gesellschaft für Weltraumforschung, Vienna, Austria, 1955).
• 17. “Mars and Beyond,” The Wonderful World of Disney television program, 4 December 1957.
• 18. Portree, NASA’s Origins, p. 12.
• 19. Ernst Stuhlinger and Joseph King, "Concept for a Manned Mars Expedition with Electrically Propelled Vehicles," Progress in Astronautics, Vol. 9 (San Diego: Univelt, Inc., 1963), pp. 647-64.
• 20. Ibid., p. 658.
• 21. Ibid., p. 648.
• 22. James Hansen, Enchanted Rendezvous: John C. Houbolt and the Genesis of the Lunar-Orbit Rendezvous Concept (Washington, DC: NASA Monographs in Aerospace History #4, 1995).