Most early Mars expedition plans made little mention of potential martian resources. Apart from using the martian atmosphere to slow the crew lander for landing, Mars spacecraft generally depended little on materials or conditions peculiar to the planet. This was because so little was known of Mars (top image above).The potential benefits of using martian resources for propellants, building materials, and life support consumables were so compelling, however, that some planners chose to incorporate them into their mission designs anyway. Chief among these benefits was a dramatic reduction in mission mass if Earth-return rocket propellants could be found at Mars.
The Working Group on Extraterrestrial Resources (WGER) formed in early 1962. Besides NASA, the group included representatives from the U.S. Air Force, the Army, the Bureau of Mines, aerospace corporations, and academe. The group, which met throughout the 1960s, focused mainly on lunar resources. A few researchers, however, treated the WGER as a forum for discussing eventual exploitation of Mars resources.
One of these forward-thinkers was Ernst Steinhoff (middle image above), representing the RAND Corporation, a think tank created in 1946 to provide advice to the U.S. military services. RAND had performed Mars studies for the Air Force as early as 1960. Steinhoff, whose specialty was rocket guidance, came to the U.S. in 1945 with Wernher von Braun, Ernst Stuhlinger, Krafft Ehricke, and the other members of the Peenemünde rocket team. After working to launch captured V-2 missiles for the Army (bottom image above), he went to work for U.S. industry in 1956. Steinhoff joined RAND in 1961, and was instrumental in the formation of the WGER the following year. He became the WGER's first chairman.
Steinhoff summed up his Mars work in papers presented at a March 1962 meeting at NASA's Marshall Space Flight Center in Huntsville, Alabama, and at the June 1963 American Astronautical Society Symposium on the Manned Exploration of Mars in Denver. George Morgenthaler of Martin Marietta Corporation organized the Denver symposium, the first non-NASA meeting devoted to piloted Mars travel. As many as 800 engineers and scientists heard Steinhoff's paper and 25 others. It was the first time so many people from Mars-related disciplines had come together in one place, and the last Mars meeting as large until the 1980s. Sky & Telescope magazine reported that the "Denver symposium. . . helped narrow the gaps between engineer, biologist, and astronomer."
Soon after the Denver symposium, Steinhoff became Chief Scientist at the Air Force Missile Development Center at Holloman Air Force Base, New Mexico, after which he continued his involvement with the WGER and his work on Mars subjects at a reduced level. This is unfortunate, because in his two papers he anticipated several Mars mission concepts that would, in time, emerge as significant in Mars exploration planning.
Steinhoff's work focused on "autarchic" - that is, self-sufficient - bases on Mars and Phobos. Self-sufficiency would be achieved through mining and processing local materials, and by equipping the base with regenerable (recycling) life support systems. The Phobos and Mars bases would support scientific research and serve as "terminals" for spacecraft.
Steinhoff estimated that extraterrestrial water could supply over 90% of the logistical needs of space-faring humans. He wrote that the moon's gravity - nearly 20% as powerful as Earth's - would make it an inefficient "interim space base" for fueling Mars-bound ships. Citing Clyde Tombaugh, who had written that Mars's moons were probably made of the same water-rich materials as Mars itself, Steinhoff proposed that Phobos supplant the moon as a stepping stone to Mars. Nuclear systems could cook water out of Phobos rocks, then split it into hydrogen and oxygen rocket propellants.
Steinhoff's early Mars expedition would comprise 18 astronauts in a convoy of three crew and six cargo spacecraft. They would use a conjunction-class profile, traveling to Mars in 256 days, remaining in the Mars system for 485 days, and then returning to Earth in 256 days.
Two chemists and two geologists would prospect Phobos for water-rich rocks. The little moon's weak gravity would enable space-suited astronauts to easily assemble "ready-to-operate" base modules shipped from Earth. Space construction workers, Steinhoff wrote, would be able to carry and connect 50-ton modules by hand.
Winged three-man shuttles based at the Phobos terminal would provide access to the Mars base, which would be built within 25º of the equator for easy access from Phobos's equatorial orbit. Steinhoff assumed that the martian atmosphere would be thick enough to support gliding shuttles requiring minimal landing propellant. He proposed that early shuttles drop cargoes and astronauts by parachute, then blast back to orbit without landing.
Among the early air-dropped cargoes would be a radio-controlled bulldozer, which astronauts on Phobos would use to prepare a safe runway ahead of the first shuttle landing. After the Mars base was established, the shuttles would rely on propellants manufactured on Mars to return to the Phobos base.
The Mars base would use vehicles and building techniques Steinhoff's RAND colleagues proposed in their Air Force studies. Rocket turbine engines tailored to the martian atmosphere would power surface rovers, airplanes, and helicopters with low-mass inflatable parts. Inflatable modules would provide living space for the earliest Mars explorers. Later astronauts would manufacture cement from martian materials, construct masonry and cinderblock buildings, and inhabit martian caves.
After the propellant needs of the Mars system were met, Phobos would become a fueling station for interplanetary spacecraft. Steinhoff estimated that enough propellant could be manufactured in just 100 days to launch a spacecraft from Phobos to 300-mile-high Earth orbit, and that Phobos propellants could cut the time required for transfer between the two worlds in half. He added that "use of indigenous resources, combined with more advanced nuclear ferry systems, may. . . pave the way to intensive interplanetary exploration within the limitations of our national resources." Phobos could, for example, serve as a refueling stop for Jupiter-bound piloted spacecraft.
"Use of Extraterrestrial Resources for Mars Basing," Ernst A. Steinhoff, Exploration of Mars, George Morgenthaler, editor, pp. 468-500; proceedings of the American Astronautical Society Symposium on the Exploration of Mars, Denver, Colorado, June 6-7, 1963."A Possible Approach to Scientific Exploration of the Planet Mars," Paper #38, Ernst A. Steinhoff, From Peenemunde to Outer Space, "A Volume of Papers Commemorating the Fiftieth Birthday of Werner von Braun," NASA Marshall Space Flight Center Technical Report, 1962, pp. 803-836.
"Manned Exploration of Mars?" Raymond Watts, Sky & Telescope, August 1963, pp. 63-67, 84.
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