January 27, 2000 -- Mars Polar Lander mission managers decided to send another set of commands to Mars this week to investigate the possibility that a signal detected by a radio dish at California's Stanford University came from the missing spacecraft.

Right: The 45-meter parabolic radio antenna at Stanford University. [more information from Stanford University]

NASA transmitted instructions several times in December and January commanding Polar Lander to send a radio signal to the 45-meter (150-foot) antenna at Stanford. Although no signal was detected in real-time, the team in charge of the Stanford antenna says that after additional processing of the data they may have detected a signal that could have come from Mars during tests on December 18 and January 4. Because the signal was so weak, it took several weeks for the Stanford team to process their data and reach this conclusion.

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A new set of commands were transmitted to Mars at 10 a.m. PST on Tuesday. They instructed the lander, if it is operating, to send a signal directly to Earth to the antenna at Stanford on Wednesday, January 26, at approximately 1 p.m. PST. The Stanford receiving station listened during the window on Wednesday to see if it picked up a signal that could originate from Mars. The results of this test will not be immediate and it will take the team several days to process the data.

"This week's test is a real long-shot, and I wouldn't want to get anyone too excited about it," said Richard Cook, Polar Lander project manager at NASA's Jet Propulsion Laboratory, Pasadena, CA. "The signal that the Stanford team detected is definitely artificial, but there are any one of a number of places it could have originated on or near Earth. Still, we need to conduct this test to rule out the possibility that the signal could be coming from Polar Lander."

Left: Since mid-December 1999, the Mars Orbiter Camera (MOC) onboard the Mars Global Surveyor (MGS) spacecraft has been taking pictures of Mars Polar Lander's landing zone near 76S, 195W, in hopes of finding some evidence as to the fate of the spacecraft that went missing during its December 3, 1999, landing attempt. This figure shows (in orange) the area covered by MOC from mid-December through January 17, 2000. [more information]

If in fact the signal were from Polar Lander, two failures would have had to occur. First, the lander's X-band radio that it would use to transmit directly to Earth would have to be broken. Second, there would have to be a problem somewhere in the relay with Mars Global Surveyor that prevented the signal from being picked up and relayed by the orbiter. It is unlikely that a broken transmitter on the lander could be fixed, and unclear whether a problem with the relay could be resolved.

Although the Stanford data from the previous tests took several weeks to process, the team expects to have results within several days now that they know what they are looking for.

Even if the signal were coming from the lander, there is little hope that any science could be returned. However, it would give the team a few more clues in trying to eliminate possible failure modes.

Mars Polar Lander is managed by the Jet Propulsion Laboratory for NASA's Office of Space Science, Washington, DC. Lockheed Martin Astronautics Inc., Denver, CO, is the agency's industrial partner for development and operation of the spacecraft. JPL is a division of the California Institute of Technology, Pasadena, CA.Web Links

NASA's Mars Exploration Program -from JPL.

Mars Polar Lander Mission Status -January 25, 2000.

Topics:

• Astrobiology
• Planets