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| Sixty-five years ago: the first rocket launch from Cape Canaveral, Florida. A captured German V-2 with an American WAC Corporal sounding rocket on top begins a low-angle flight to a downrange distance of at least 320 kilometers. Image credit: U.S. Army/NASA |
The potential benefits of using martian resources to make spacecraft 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 the anticipated benefits was a dramatic reduction in spacecraft mass if raw materials for rocket propellants could be found at Mars. Reducing mission mass meant fewer expensive, temperamental rockets would be needed to launch Mars spacecraft components and propellants into Earth orbit for assembly, which in turn meant reduced mission cost and risk.
The Working Group on Extraterrestrial Resources (WGER) was formed in early 1962. Besides NASA, the group included representatives from the U.S. Air Force, the U.S. Army, the U.S. Geological Survey, the Bureau of Mines, aerospace corporations, and universities. The group, which met throughout the 1960s, focused mainly on lunar resources. A few researchers, however, used the WGER as a forum for discussing eventual exploitation of Mars resources.
One of these bold forward-thinkers was Ernst Steinhoff, 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 U. S. 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 other members of the Peenemünde rocket team.
After working to launch captured, sometimes modified, V-2 missiles for the U.S. Army - the image at the top of this post shows the 24 July 1950 launch of the two-stage Bumper 8 rocket - Steinhoff went to work for U.S. industry in 1956. He joined RAND in 1961, and was instrumental in the formation of the WGER the following year. In fact, he became the WGER's first chairman.
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| Mars pioneer Ernst Steinhoff. Image credit: U.S. Air Force |
Near the end of 1963, soon after he chaired the second annual meeting of the WGER (23-25 October 1963), Steinhoff could not pass up an offer to become Chief Scientist at the Air Force Missile Development Center at Holloman Air Force Base in Alamogordo, New Mexico. When he assumed his new responsibilities, his involvement in the WGER and his work on Mars subjects suffered. This is unfortunate, for in his Huntsville and Denver papers he anticipated and promoted mission concepts which would, with the passage of decades, emerge as highly significant in Mars exploration planning. Had he continued his work at RAND, he might have further promoted his ideas, and that might have changed the course of Mars mission planning in the 1960s and beyond.
Steinhoff's work focused on "autarchic" – that is, self-sufficient – bases on Mars and Phobos. Self-sufficiency would be achieved through mining and processing of 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 transportation "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 strong 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 chemical rocket propellants.
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| Image of Mars captured at Mt. Wilson Observatory in 1956, the year of the last close Mars opposition at the time Steinhoff wrote his papers. Because Mars has a decidedly elliptical orbit, the Earth-Mars distance during oppositions varies over a roughly 15-year cycle. The next close opposition would occur in 1971; the next after that was in 1988; and the most recent took place in 2003. Another will take place in 2018. When Steinhoff speculated on the nature of martian resources, this was among the best images of Mars available. Image credit: Mt. Wilson Observatory/NASA |
Two chemists and two geologists would prospect on 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. (Steinhoff apparently forgot that weightless objects retain their mass. Astronauts can move massive objects, it is true, but only through considerable exertion, and only if they have a firm footing and adequate handholds. Stopping a massive object in weightlessness requires as much effort as setting it in motion.)
Reusable winged three-man shuttles based at the Phobos terminal would provide access to Mars's surface. In common with most Mars planners of his day, Steinhoff assumed, based on the consensus view of Earth-based astronomers, that the martian atmosphere would be about 10% as dense as Earth's - that is, thick enough to support gliding shuttles requiring minimal landing propellants.
Mars's surface would be rough, Steinhoff expected, so the first gliding shuttle landing would be a difficult proposition. He proposed that early shuttles should parachute drop cargo and astronauts, then blast back to Mars orbit without landing. Among the early air-dropped cargoes would be a radio-controlled bulldozer, which astronauts on Phobos would remote-control to build a smooth, level runway for the first Mars shuttle landing. This was probably the first time anyone proposed to teleoperate equipment on Mars from orbit.
The runway would be built within 25º of the martian equator so that it could be reached with relative ease from Phobos' equatorial orbit. The first Mars surface base would be established near the runway. Inflatable modules would provide living space for early explorers. After the Mars base became operational, shuttles would rely on propellants manufactured from Mars water to return to the Phobos base.
The Mars base would use vehicles and building techniques that Steinhoff's RAND colleagues had proposed in their Air Force studies. Rocket turbine engines tailored to the martian atmosphere - which many expected would be made mostly of nitrogen, as is Earth's atmosphere - would power surface rovers, airplanes, and helicopters with low-mass inflatable parts. Astronauts would manufacture cement from martian materials, construct masonry and cinder-block 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 Mars and Earth 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.
Sources
"Powerplants for Atmospheric and Surface Vehicles on Mars," Research Memorandum RM-2529, W. H. Krase, The RAND Corporation, 10 April 1960
"Vehicles for Exploration on Mars," Research Memorandum RM-2539, T. F. Cartaino, The Rand Corporation, 30 April 1960
"A Possible Approach to Scientific Exploration of the Planet Mars," Paper #38, Ernst A. Steinhoff, editor, From Peenemünde to Outer Space, "A Volume of Papers Commemorating the Fiftieth Birthday of Wernher von Braun," NASA Marshall Space Flight Center Technical Report, 1962, pp. 803-836
"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, 6-7 June 1963
"Manned Exploration of Mars?" Raymond Watts, Sky & Telescope, August 1963, pp. 63-67, 84
Report of the Second Annual Meeting of the Working Group on Extraterrestrial Resources on October 23-25, 1963, at the Air Force Missile Development Center, Holloman Air Force Base, Alamogordo, New Mexico, MDC-TR-63-7, no date (1965?)
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