Polar Lander's silence deals NASA a setback.
Coming soon after the demise of Lander's sister craft, the Mars Climate Orbiter (SN: 10/9/99, p. 229), this loss appears to have dealt the space agency a critical setback in its decade-long campaign to study the Red Planet and bring back surface samples by 2008.
"These two failures have given us a wake-up call," NASA chief scientist Edward J. Weiler told reporters on Dec. 7. "We are going to take a major rethinking of our Mars ... program."
Although he said the program's science goals would remain the same, the agency will reevaluate its current strategy of launching an orbiter and a lander to the Red Planet every 2 years, when Mars and Earth are at their closest. "Maybe we were a little too aggressive," Weiler suggests.
NASA had slated its next Mars mission for launch in 2001, but that could be cancelled or delayed. Weiler says, "Right now, I have no confidence that that will be a successful mission." He noted the need for better information on landing sites and improved communication between Mars missions and Earth, including the capability of craft to report their status while they're descending through the Martian atmosphere.
Because of weight and cost constraints, Lander did not have a transmitter with that capability. That's making it difficult to determine exactly why the craft fell silent. It has also prompted some critics to question the space agency's motto of "faster, better, cheaper."
"People are going to start asking whether or not the pendulum has swung too far to the cheaper," says space-policy analyst Marcia S. Smith of the Congressional Research Service in Washington, D.C.
"Given the resources, we basically did the best we could," says Lander scientist David Crisp of NASA's Jet Propulsion Laboratory (JPL) in Pasadena, Calif. He adds that Lander featured the last weather station NASA has planned for Mars. "In my view, it would be foolhardy to think that we're going to be able to safely land spacecraft on the face of Mars" without more climate information, Crisp says.
Lander was also to have taken the first close-up images of Martian soil and searched for underground ice deposits. A robot arm would have scooped up samples and dumped them into tiny ovens that can detect water and carbon dioxide.
NASA admitted likely defeat early on Dec. 7, minutes after Mars Global Surveyor, flying over Lander's presumed resting spot near the Red Planet's south pole, failed for a second time to detect a signal from the craft's ultra-high-frequency antenna. "The Mars Polar Lander flight team played its last ace," project manager Richard Cook of JPL told reporters.
Combined with multiple attempts from Earth to coax a signal from Lander, these efforts appear to rule out two of the simplest explanations for Lander's silence--that the craft's main antenna was not pointed at Earth and that the craft had placed itself in temporary hibernation.
Lander carried two probes designed to separate from the craft and plunge without a parachute into the Martian surface. JPL scientists now calculate that these experimental devices, which can transmit signals on their own for a few days, are likely to have plowed into a crater. Landing in such rugged terrain could have damaged the transmitters or interfered with communication.
Exploring the climate of the Red Planet's forbidding south pole "was literally a once-in-a-lifetime opportunity," says Crisp.
He told SCIENCE NEWS that he won't give up all hope of hearing from the craft for a few more weeks. According to instructions previously programmed, Lander was to have automatically shifted to a second radio transmitter on Dec. 9. A few days later, it was to have switched to a backup computer. This could make a difference in the craft's ability to contact its home planet, Crisp says.
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|Title Annotation:||Mars exploration|
|Article Type:||Brief Article|
|Date:||Dec 11, 1999|
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