[meteorite-list] Ground Team Stays Busy on 10th Anniversary of Mars Global Surveyor Launch

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Wed Nov 8 11:26:19 2006
Message-ID: <200611081626.IAA20736_at_zagami.jpl.nasa.gov>

http://www.jpl.nasa.gov/news/features.cfm?feature=1226

Ground Team Stays Busy on 10th Anniversary of NASA Mars Launch
Media contact: Guy Webster (818) 354-6278/JPL
Jet Propulsion Laboratory
November 07, 2006

Engineers are striving to restore full communications with NASA's Mars
Global Surveyor on the 10th anniversary of the spacecraft's Nov. 7,
1996, launch.

The orbiter is the oldest of five NASA spacecraft currently active at
the red planet. Its original mission was to examine Mars for a full
Martian year, roughly two Earth years. Once that period elapsed,
considering the string of discoveries, NASA extended the mission
repeatedly, most recently on Oct. 1 of this year.

The orbiter has operated longer than any other spacecraft ever sent to
Mars. It has returned more information about Mars than all earlier
missions combined and has succeeded far enough beyond its original
mission to see two later NASA orbiters arrive: Mars Odyssey and Mars
Reconnaissance Orbiter. Among many important accomplishments so far,
Mars Global Surveyor has found many young gullies apparently cut by
flowing water, discovered water-related mineral deposits that became a
destination for NASA's Opportunity rover, mapped the planet
topographically and examined many potential landing sites on Mars.

On Nov. 2, one orbit after commands were sent for a routine maneuver to
move the solar panels, the spacecraft reported that the motor moving one
of the arrays had experienced errors. Onboard software responded as
programmed, switching the spacecraft to a backup motor controller, then
to a backup circuitry connection.

Following these indications of difficulty, a two-day lapse in contact
occurred on Nov. 3 and 4. The signal from the spacecraft was received on
Nov. 5 during four different orbits, but it did not carry any data from
the spacecraft. The signal's frequency indicated that the spacecraft had
entered safe mode, a pre-programmed state of restricted activity in
which it awaits instructions from Earth.

No further signal was heard during subsequent orbits on Nov. 5 and Nov.
6. Engineers concluded that the spacecraft had made an additional
pre-programmed response, intended to help it survive when it senses that
a solar array is stuck. The spacecraft turns that array toward the sun
to maintain its power supply and rotates the rest of the spacecraft in
the same direction, thereby making communication with Earth less effective.

"The spacecraft has many redundant systems that should help us get it
back into a stable operation, but first we need to re-establish
communications," said Tom Thorpe, project manager for Mars Global
Surveyor at NASA's Jet Propulsion Laboratory, Pasadena, Calif.

Further information on the recovery of the spacecraft will be released
as it comes available.
Received on Wed 08 Nov 2006 11:26:16 AM PST