In a report released this week, the National Research Council criticized some aspects of upcoming NASA robotic missions to Mars, claiming that the missions were not sophisticated enough to do the thing that is now of the greatest interest among researchers: look for signs of past life on the red planet.
       "Cost and payload limitations imposed on Mars Surveyor's small landers might prevent the flight of advanced rovers capable of adequate sampling of the rock record," the Committee on Planetary and Lunar Exploration (COMPLEX), part of the NRC, concluded in its report.
       "Because evidence for past climate changes and ancient life, if any, is most likely embedded in the rocks, this is a major shortcoming," they added.
       The problem, according to the report, is that the planned series of Mars Surveyor missions, scheduled for approximately every two years between this November and 2005, are strongly constrained by the need to keep costs down. This requires cheaper, less powerful boosters, and hence a smaller spacecraft.
       This problem could be remedied by developing lightweight but powerful scientific instruments for the spacecraft, but funding for instrument development is not a priority. "Because funding within the Surveyor program is too limited to foster significant development of so-called microinstruments, the scientific objectives of the program could be seriously undermined unless instrument development is externally supported," the committee reported.
       The small size of the rovers, such as the microrover "Sojourner" that is part of this fall's Mars Pathfinder mission, will make exploration of the surface and the search for clues of past life difficult. "A... concern is that as the program progresses it may become increasingly difficult to make major discoveries with the small landers currently envisaged."
       "In any transition to more ambitious missions, including sample return, long-range rovers equipped with significant instrumentation may be necessary for the definitive resolution of questions concerning past climates and history."
       The committee made a number of recommendations that would enhance the scientific goals of the missions and make it more feasible to discover evidence of life on the planet. Those recommendations included developing larger, more advanced rovers; starting an "aggressive" program for developing small instruments; keeping the plans for upcoming missions flexible; and to seek out international cooperation wherever possible.
       Despite the committee's criticism of certain aspects of the Mars Surveyor missions, they were generally pleased with the possible scientific results the missions will provide. "The Mars Surveyor program... provides a major opportunity to broaden and deepen our understanding of Mars -- its atmosphere and climate, its geochemistry and geophysics, and, to a somewhat lesser extent, its present and past potential for harboring life."
       The committee also praised the general plan of the program, where missions are spread out over a ten-year period. This strategy, as opposed to launching a few large spacecraft, allows mission planners to take bolder risks.