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Mars Polar Lander Mission Status

December 4, 1999 11:15 p.m.

Mission controllers for NASA’s Mars Polar Lander are proceeding with
their checklist in a continuing attempt to communicate with the spacecraft.

On Sunday, Dec. 5 from 10:50 to 11:00 a.m. Pacific Standard Time,
they will try to hear the lander’s signal by using NASA’s currently-orbiting
Mars Global Surveyor spacecraft as a relay system for the lander’s UHF
radio. Until this point, engineers have tried to reach the lander via its
medium gain antenna.

Controllers did not hear from the spacecraft during a communications
opportunity on Saturday, Dec. 4 at 8:30 p.m. PST. They hoped to make contact
during that window if, after landing, the spacecraft had successfully
pointed its antenna toward Earth, then entered a safe, or standby mode.

“Now we can cross that scenario off the list,” said Mars Polar Lander
project manager Richard Cook of JPL. “We’re ready to move on to the next
possibility on Sunday morning, which we hope will work if the spacecraft is
not in safe mode, but has its antenna pointed incorrectly. We’re sprouting
ideas as we go along about how to contact the lander.”

If contact is not established during that attempt, additional
attempts scheduled at this point will be made as follows:

– Sunday, Dec. 5, from 10:10 to 11:10 p.m. using the lander’s medium
gain antenna scan if it is in safe mode but its antenna is not pointed

– Tuesday, Dec. 7, at 12:20 a.m. PST using Mars Global Surveyor if
Mars Polar Lander is in safe mode.

Analysis of the landing site reveals the spacecraft would have
touched down within 10 kilometers (6 miles) of the target site on the
Martian south pole, according to Dr. Sam Thurman at JPL, the lander’s flight
operations manager. He said they see no surface features that would obstruct
the lander’s view of Earth and therefore hamper its communications

Engineers for the Deep Space 2 microprobes are continuing their
attempts to communicate with the probes every two hours. The microprobes,
designed to impact Mars about 60 kilometers (about 35 miles) north of the
lander, will transmit data through Mars Global Surveyor.

“The probes may have arrived in an area of high slopes, rough terrain
or sand dunes,” 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. “It’s
also possible that the probes’ batteries have not warmed sufficiently to
power up the communications system. We’re checking into all possibilities.”

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.