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Mars Polar Lander Mission Status

December 4, 1999, 5:45 p.m. PST

Flight controllers for NASA’s Mars Polar Lander have another
opportunity to listen for a signal from the spacecraft beginning tonight at
8:30 p.m. PST. In a meeting late this afternoon they decided to listen for
the lander during the first 30 minutes of the communications window, then
they would transmit commands to the medium-gain antenna telling the
spacecraft to search for Earth.

One scenario that would explain why engineers have not yet heard from
the lander is that the spacecraft entered standby, or “safe mode,” about 20
minutes after landing shortly after 12 noon PST Friday, Dec. 3. If the
lander entered safe mode at that time, it would not be able to receive any
communication until it “wakes up” this evening. It would be preprogrammed by
onboard software to start looking for Earth starting at noon on Mars, or
about 8:30 p.m. PST. The communication window lasts until 10:45 p.m. PST.

If contact has not been established by Sunday morning, Dec. 5, flight
controllers will listen to see if the lander transmits via a UHF radio to
the currently orbiting Mars Global Surveyor spacecraft. The lander would do
that at about 10:50 a.m. PST Sunday if it did not receive commands from
Earth telling it not to do so.

Engineers working on NASA’s Deep Space 2 microprobes have additional
opportunities to hear from the probes this evening at about 5:30 p.m. and
7:30 p.m. PST through the Global Surveyor relay. The probes would
automatically begin to transmit at those times if their radio receivers were
unable to pick up commands from Global Surveyor.

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.