|Craters inside craters inside craters: Hadley crater, Mars, in colors indicative of depth. Each new impact dug deeper, exposing more of Mars's complex history to exploration. Image credit: NASA.
What is more surprising is that, as early as 1965, NASA's Marshall Space Flight Center (MSFC) turned its attention to the scientific tasks astronaut-scientists might perform on Mars. In that year, as part of an ongoing series of Mars mission studies that began in 1962 with the EMPIRE piloted Mars/Venus flyby/orbiter study, the Huntsville, Alabama-based NASA center contracted with Avco/RAD to study piloted Mars surface operations. This truly was far-sighted thinking; when MSFC contracted with Avco/RAD, NASA, with President John F. Kennedy's end-of-decade deadline for a piloted lunar landing fast approaching, had barely begun to pay serious attention to the scientific tasks that Apollo astronauts would perform on the moon.
Paul Swan, who had worked with Cornell astronomer Carl Sagan in 1964 to identify landing sites for automated Voyager Mars landers, was Avco/RAD's study leader. In a summary paper presented at the March 1966 Stepping Stones to Mars meeting (the last major Mars-focused engineering meeting until the 1980s), Swan and three of his Avco/RAD colleagues explained that an "understanding of the possibilities and limitations of [human explorers on Mars] should serve both to keep our eyes on a far horizon, and to guide our footsteps on the early stepping stones which must be negotiated."
The first successful robotic Mars probe, 261-kilogram Mariner IV, had flown past the planet on 14-15 July 1965, while the Avco/RAD engineers performed their study, and they included in their report references to its findings. They noted, for example, that Mariner IV had imaged overlapping craters (implying a lack of erosion, hence little water) and had found no evidence of a martian magnetosphere (implying that solar flare radiation could reach its surface mostly unchecked). In general, however, the Avco/RAD team adhered to the optimistic pre-Mariner IV view of Mars, which was based on a century of Earth-based telescopic observations. Their Mars was, for example, etched by a mysterious network of slender, linear canals, though no such features appeared in Mariner IV images.
|First look: one of the best of the 21 images of Mars the Mariner IV flyby spacecraft beamed to Earth in July-August 1965. Image credit: NASA.
Swan's team acknowledged that the decision to send humans to Mars might be taken "for reasons of international competition, for domestic political considerations, or to stimulate the economy," but hastened to add that such justifications should not be permitted to dictate the science activities that would take place during piloted Mars exploration. They assumed that science would dictate engineering requirements for Mars spacecraft, space suits, and rovers, and not the reverse. Though necessarily simplistic, this approach put aside uncertainty about Mars exploration objectives.
Mars, the team told the Stepping Stones conference, would not be explored as Earth has been explored. On Earth, scientists can usually visit a field site, gather data, return to the lab to study the data and formulate new questions, and then return to the field site to perform new investigations. Because the cost of exploring Earth is small compared to that of exploring Mars, terrestrial exploration can, in other words, be iterative and open-ended.
Mars astronaut-scientists, on the other hand, would need to gather rapidly as much data at their landing site as possible, because the large number of interesting potential landing sites and the difficulty and cost of reaching Mars would make unlikely an early return to any one site that was visited. To accommodate this fundamental constraint, Avco/RAD called for every piloted Mars mission to conduct a range of experiments that would metaphorically cast a fine-meshed net over its landing site with the aim of capturing "variable amounts of different kinds of information over wide dynamic ranges."
The team noted that the likely existence of "totally . . . unanticipated phenomena" would complicate data gathering. To illustrate this, Swan and his colleagues asked their audience to consider "the plight of the Martian astronaut-scientist who finally manage[d] to reach Earth, but completely failed to anticipate magnetic fields greater than a few gammas, and therefore also magnetospheres, Van Allen belts . . . and all other phenomena associated with the mere existence of the Earth's magnetic dipole."
|Deimos, outermost of Mars's two small satellites, remains enigmatic. Image credit: NASA.
Swan's team proposed two piloted Mars mission scenarios designed to explore these spheres of scientific interest. The first, the "minimal" missions, would occur between 1976 and 1986 and would use Apollo-level (that is, 1970) technology. The second, the "extended" mission, was tentatively scheduled to occur in the 1982-1986 time period. It would require technologies beyond the Apollo state of the art.
The four minimal-mission surface crew members would explore a landing site within 30° of the martian equator for 21 days during a period when the biosphere at the site was at "peak growth." While the four surface astronaut-scientists did their best to keep up with "a very active schedule" of wide-ranging data-gathering, two astronauts would orbit Mars on board the mission "mothership," the command module. Among other tasks, they would deploy automated probes to investigate the martian moons and any dust belts. Time near Mars would total 40 days.
The Avco/RAD team expected that, in addition to the Mars-orbiting command module, the minimal mission would need three landed modules. These would reach the landing site on common-design landers. The modules would include a drum-shaped, 9500-pound "main shelter" where the four surface astronauts would live and work; a two-person, 8700-pound, 20-foot-long pressurized Molab rover capable of three five-day, 500-mile surface traverses over the course of a 21-day surface mission; and a 1550-pound "garage" module for storing the Molab, 2050 pounds of Molab expendables, and 3000 pounds of science equipment.
The surface crew would remain sequestered from all martian life throughout their stay. After every Mars walk, space-suited astronaut-scientists would undergo decontamination, and samples they gathered would remain sealed in quarantine until they were returned to Earth laboratories and found to be safe.
This degree of caution would be necessary, the Avco/RAD team wrote, because determining conclusively the degree of pathogenicity of martian life would probably not be possible during a three-week surface stay. If the surface crew became exposed to a virulent martian bacterium, its effects would probably not have time to become readily apparent before they returned to the orbiting command module. The crew in orbit would then become exposed, and the infection might be transmitted to Earth.
|The south polar ice cap of Mars. Image credit: ESA.
At least six common-design landers would deliver eight modules to each base site, for a total of eighteen landers and 24 modules on Mars. For redundancy, two 80-kilowatt nuclear reactors would supply each base with electricity and two main shelters with regenerative life support would house each base crew. A pair of "storage and maintenance shelters" at each base site would house two 22,000-pound, two-man Molabs capable of 30-day, 1500-mile traverses, plus a total of 34,000 pounds of Molab expendables and science equipment.
"Martian Landing Sites for the Voyager Mission," P. Swan and C. Sagan, Journal of Spacecraft and Rockets, January-February 1965, pp. 18-25.
NASA Facts: A Report from Mariner IV, NASA Facts, Vol. III, No. 3, 1966.
"Manned Mars Surface Operations," P. Swan, R. Hanselman, R. Ryan, and R. Suitor, A Volume of Technical Papers Presented at the AIAA/AAS Stepping Stones to Mars Meeting, pp. 69-86; paper presented in Baltimore, Maryland, 28-30 March 1966.
After EMPIRE: Using Apollo Technology to Explore Mars and Venus (1965)
Gumdrops on Mars (1966)
A Forgotten Pioneer of Mars Resource Utilization (1962-1963)
Dyna-Soar's Martian Cousin (1960)