SAN FRANCISCO — Stunned by the loss of two consecutive Mars missions, some American space scientists say NASA is setting its goals without adequate assessment of the risks. One way to help fix the problem: Consult more scientists.
The key to success for NASA's program of buying spacecraft on a food-stamp budget is to be a lot more careful in setting mission goals, said Mars Polar Lander investigator David Paige, speaking at a meeting here of the American Geophysical Union. And that means being precise about what is to be accomplished.
It also means not announcing goals before knowing what risks are involved. "We are going to get into trouble" unless the detailed steps needed to accomplish the goals are in place before mission plans are set and spacecraft design frozen, he said. "That is part of what has happened" on Mars in recent days.
The lander's goal - to look for water near the south polar cap - is important, said Dr. Paige, a planetary scientist from the University of California at Los Angeles, agreeing with many other planet investigators at the meeting. But many of them also said trying to land on unknown terrain involved many uncertainties.
The lander needed almost level ground. No one yet knows what went wrong, but it could have landed perfectly only to lose its balance on uneven ground. It would have been preferable, they said, to wait for better knowledge of the landing site before launching the craft.
That information could be coming relatively soon. Over the next few years, the Mars Global Surveyor, which is now orbiting the planet, will map the Martian landscape in unprecedented detail, says David Smith, principal investigator for the craft's laser altimeter. Then, "we will have a much better idea of where we are going" with future landers, added Dr. Smith, who works at NASA's Goddard Space Flight Center in Greenbelt, Md.
The lander team continues to search for the craft. Project scientist Richard Zurek of the Jet Propulsion Laboratory (JPL) in Pasadena, Calif., said the team has refined its estimate of the touchdown site. The Surveyor will try to image the site. The lander is too small to see, but its parachute may show up. That would show the craft reached the surface, narrowing the potential causes of failure.
The two microprobes that accompanied the lander are another story. Suzanne Smrekar, probe project scientist at JPL, says the project is a partial success because it produced equipment that can survive a high-speed impact. But it would be nice to have the lost science, too, she added.
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