Mars Exploration Rover Mission Status
January 22, 2004
Flight-team engineers for NASA's Mars Exploration Rover Mission
were encouraged this morning when Spirit sent a simple radio
signal acknowledging that the rover had received a transmission
from Earth.
However, the team is still trying to diagnose the cause of
earlier communications difficulties that have prevented any data
being returned from Spirit since early Wednesday.
"We have a very serious situation," said Pete Theisinger of
NASA's Jet Propulsion Laboratory, project manager for Spirit and
its twin, Opportunity.
Spirit did send a radio signal via NASA's Mars Global Surveyor
orbiter Wednesday evening, but the transmission did not carry
any data. Spirit did not make radio contact with NASA's Mars
Odyssey during a scheduled session two hours later or during
another one Thursday morning. It also did not respond to the
first two attempts Thursday to elicit an acknowledgment signal
with direct communications between Earth and the rover, and it
did not send a signal at a time pre-set for doing so when its
computer recognizes certain communication problems. The
successful attempt to get a response signal came shortly before
9 a.m. Pacific Standard Time.
No single explanation considered so far fits all of the events
observed, Theisinger said. When the team tried to replicate the
situation in its testing facility at JPL, the testbed rover did
not have any trouble communicating. Two of the possibilities
under consideration are a corruption of flight software or
corruption of computer memory, either of which could leave
Spirit's power supply healthy and allow adequate time for
recovering control of the rover.
Engineers will continue efforts to understand the situation in
preparation for scheduled communication relay sessions using
Mars Global Surveyor at 7:10 p.m. PST and Mars Odyssey at 10:35
PST. Efforts to resume direct communications between Spirit and
antennas of NASA's Deep Space Network will resume after the
rover's expected wake-up at about 3 a.m. PST Friday.
Meanwhile, mission leaders decided to skip an optional
trajectory correction maneuver today for Opportunity, the other
Mars Exploration Rover. Opportunity is on course to land
halfway around Mars from Spirit, in a region called Meridiani
Planum, on Jan. 25 (Universal Time and EST; Jan. 24 at 9:05 p.m.
PST).
JPL, a division of the California Institute of Technology
in Pasadena, manages the Mars Exploration Rover project for
NASA's Office of Space Science, Washington, D.C.
Additional information about the project is available from
JPL at http://marsrovers.jpl.nasa.gov and from Cornell
University, Ithaca, N.Y., at http://athena.cornell.edu.
