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NASA hopes Mars lander heeds wake-up call
December 4, 1999
From staff and wire reports PASADENA, California (CNN) -- NASA scientists remain hopeful that the silent Mars Polar Lander will communicate with Earth this weekend. The probe has failed to communicate during three opportunities, but NASA engineers hope to detect a signal sometime after 11:30 p.m. EST on Saturday.
The $165-million lander has not been heard from since it turned its antenna away from Earth on Friday to begin a descent near the red planet's south pole. Richard Cook, the Jet Propulsion Laboratory project operations manager, said the craft could have gone into a "safe mode" about 20 minutes after it made a landing, explaining why it had failed to call home across 165 million miles of space. He said the craft's onboard computer was programmed to go into a safe mode if one of the lander's many instruments had failed or was temporarily malfunctioning. At the Jet Propulsion Laboratory, mission engineers ate peanuts, a NASA good luck tradition. "A little thing could easily have caused the spacecraft to put itself to sleep until tomorrow," engineer Rob Manning said Friday. "So the spacecraft may be snoring right now, waiting for tomorrow ... and it drives us nuts, of course."
"If it was asleep, which in essence is what happens in a safe mode, then the lander would not be able to hear us when we sent instructions," Cook said. The craft is programmed to stay in a safe mode for 18 hours and would not wake up until 9:30 p.m. EST.
At that time, JPL engineers will send a signal to the lander asking it if it is awake and commanding it to start scanning the Martian sky until its main antenna locks on Earth. The earliest the craft could respond would be during a two- hour transmission window beginning at 11:30 p.m. EST, said Laurie Leshin, a member of the mission's science team. Mission controllers say they have not exhausted other simple explanations for the lack of a signal, such as a misdirected antenna. The spacecraft was in good shape and on course just before communications ended as expected before the descent.
"We're not down yet. We're a long way from giving up hope," Phil Knocks, a mission engineer at NASA's Jet Propulsion Laboratory, told CNN. Leshin said that if the craft was still not able to receive commands, there is a built-in command sequence in the lander's onboard computer to tell it to switch to its Ultra High Frequency antenna Sunday night and beam signals to the Mars Global Surveyor, a satellite orbiting Mars on a mapping mission. If that succeeds, engineers can then order the craft to switch to backup systems to bypass whatever problems it has been having, Leshin said. In a rare lighthearted moment, technicians at the Pasadena, California, command center held up signs spelling out, "MPL Phone Home."
The embarrassing September 23 loss of the lander's $125 million sibling spacecraft, the Mars Climate Orbiter, is not far from the minds of JPL controllers. NASA investigators later determined that engineers failed to convert data into metrics in a critical navigation program, causing the Climate Orbiter to fly far too close to Mars. The orbiter is believed to have burned up in the atmosphere it was to study. NASA scientists had hoped to use the orbiter to relay data between the lander and Earth. The lander's mission has come under scrutiny because the same organizations and people who flew the orbiter were behind the latest mission. Two microprobes that were to jettison from the descending lander and touch down at separate locations have also failed to communicate with Earth. During its 90-day mission, the lander's primary task is to search for signs of water, considered a prerequisite for life. Correspondents John Zarrella , Jim Hill , The Associated Press and Reuters contributed to this report. RELATED STORIES: Mars mission is prelude to manned exploration RELATED SITES: Mars Polar Lander: Official Web site
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3D models
Space Correspondent Miles O'Brien profiles a man with a plan to get to Mars and, more importantly, back
