JET PROPULSION LABORATORY
http://www.jpl.nasa.gov
December 10, 1999
Flight controllers for Mars Polar Lander continued their attempts to communicate with the spacecraft yesterday and today so that they can be certain they have exhausted all possibilities before they conclude their search. While a recovery is still a possibility, the likelihood of hearing from the lander is considered remote at this point.
Yesterday morning at about 2:45 a.m. PST, the team sent commands to begin a lengthy "big sweep" during which the lander uses its steerable medium-gain antenna to scan across the sky. Presumably, it would eventually scan across the area where Earth is and its carrier wave signal would be heard by the Deep Space Network.
Other communication attempts took place today at 3:00 and 6:00 p.m. PST with the 46-meter (about 150-foot) antenna at Stanford University, Palo Alto, Calif., which listened for a signal from the lander's UHF antenna. An earlier attempt by Stanford that had been scheduled for Tuesday was postponed when the Stanford antenna experienced mechanical problems.
The "big sweep" will conclude tonight. Engineers will then begin a process of sending commands to the spacecraft to switch to back-up hardware and will then repeat some of the communications attempts they have already tried.
Mission planners are also working to implement a plan to use Mars Global Surveyor to take pictures of the landing site for Mars Polar Lander starting sometime next week in hopes of spotting the spacecraft or parachute.
Review boards will be set up within JPL and at NASA to study the cause of the apparent loss and explore ways to prevent a recurrence.
December 7, 1999, 1:45 a.m.
Mission controllers for NASA's Mars Polar Lander acknowledge that they hold out very little hope of communicating with the spacecraft, but they vow to learn from the experience and continue exploring the Red Planet.
"The Mars Polar Lander flight team played its last ace," said the lander's project manager Richard Cook of JPL following an unsuccessful attempt early Tuesday morning to get the lander to talk to Earth via NASA's currently orbiting Mars Global Surveyor.
Cook said the team will continue trying to communicate with the lander for another two weeks or so, but that expectations for success are remote. Nonetheless, Cook praised the flight team for its heroic attempts to contact the spacecraft, even sleeping on the floors of their offices at times. "We're certainly disappointed, but we're extremely determined to recover from this and go on."
The next communication attempt will take place late Tuesday afternoon, when a 46-meter (about 150-foot) antenna at Stanford University, Stanford, Calif., will listen for a signal from the lander's UHF antenna. Engineers will command the spacecraft to use its medium-gain antenna on Wednesday to begin a scan of the entire sky. During the scan, the antenna is being asked to bend and stretch in every possible direction, in essence "craning its neck" in an effort to be heard by mission controllers on Earth.
Engineers are also considering a plan to command Mars Global Surveyor to fly over the landing site for Mars Polar Lander in coming weeks and take pictures of the area in hopes of spotting the spacecraft.
The Deep Space 2 microprobes that accompanied Mars Polar Lander have also been silent, and project manager Sarah Gavit said she couldn't envision any failure scenario in which the batteries could still hold a charge after four days on Mars.
"Just getting the probes to the launch pad was a measure of success," Gavit said, pointing out that as part of NASA's New Millennium program, the probes were designed to develop and test new technologies in preparation for future missions.
Review boards will be set up within JPL and at NASA to study the cause of the apparent loss and explore ways to prevent a recurrence.
"What we're trying to do is very, very difficult," Cook said. "We hope people, and children in particular, will see from this experience that the mark of a great person, or group of people, is the ability to persevere in the face of adversity."
December 5, 1999
Mission controllers for NASA's Mars Polar Lander have revised their strategy as they continue trying to make contact with the spacecraft.
"We're nearing the point where we've used up our final silver bullets," said the mission's project manager, Richard Cook of JPL, after Sunday night's unsuccessful attempt to communicate with the spacecraft.
Engineers will try to contact the lander again on Tuesday, Dec. 7 at 12:20 a.m. Pacific Standard Time, by directing Mars Polar Lander to use its UHF radio to communicate through a relay system onboard NASA's currently-orbiting Mars Global Surveyor. Most of the attempts to receive a signal from the lander over the past few days have used its medium gain antenna.
"Our probability of success will diminish significantly after this next attempt," Cook said, "but the team is still exploring all possibilities for establishing comunications with the lander."
Controllers are preparing a set of computer commands to have the lander conduct a full sky search for Earth within the next couple of days.
December 5, 1999
Another telecommunications strategy to hear from NASA's Mars Polar Lander produced no results today, but the mission flight team is proceeding through its contingency checklist in continuing attempts to communicate with the spacecraft.
From about 11 to 11:30 a.m. PST today, the team listened for but detected no signals from the lander's UHF transmitter, which would have been relayed through the already-orbiting Mars Global Surveyor spacecraft. This was the first attempt at using the Global Surveyor; until then, engineers had tried to use the lander's medium gain antenna to transmit directly to Earth.
"We continue to work through our plan, which gives us confidence that we haven't exhausted all the possibilities," said Mars Polar Lander Project Manager Richard Cook. "But clearly, the team is getting more frustrated" as attempts to reach the lander yield no results.
No contact has yet been made in continuing efforts to communicate with the two Deep Space 2 Mars microprobes that also impacted Mars about 60 kilometers (abut 35 miles) north of the lander on Dec. 3, said Deep Space 2 Project Manager Sarah Gavit. Mission engineers believe the probes have entered a phase where they broadcast their data automatically for one minute out of every five.
Gavit said that data from last night's try at hearing signals from the probes that could have been recorded on NASA's Mars Global Surveyor orbiter would be reviewed later today. The team will also look for microprobe signals that could be relayed by Global Surveyor during another transmission today, she said. "If we haven't heard from them in the next 24 hours (by about noon Monday PST), we will have exhausted our opportunities to hear from them."
Tonight, Sunday, Dec. 5 from 10:10 to 11:10 p.m., an attempt will be made to listen for signals from the lander that would be sent through its medium gain antenna if the lander is in safe, or standby mode, and its antenna is not pointed correctly.
On Tuesday, Dec. 7, at 12:20 a.m. PST, attempts to hear signals from the lander's UHF transmitter will be made again using Mars Global Surveyor. This attempt would detect signals if Polar Lander is in safe mode. After Tuesday's post-midnight attempt, Cook said, "I think we will be at the point of diminishing returns in terms of getting in contact with the lander."
Mars Polar Lander is part of a series of missions in a long- term program of Mars exploration managed by JPL for NASA's Office of Space Science, Washington, D.C. JPL's industrial partner is Lockheed Martin Astronautics, Denver. JPL is a division of the California Institute of Technology in Pasadena.
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