[meteorite-list] Spirit Mars Rover May Have Begun Months-Long Hibernation

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Wed, 31 Mar 2010 16:41:07 -0700 (PDT)
Message-ID: <201003312341.o2VNf7sL015299_at_zagami.jpl.nasa.gov>

http://www.jpl.nasa.gov/news/news.cfm?release=2010-106

Spirit May Have Begun Months-Long Hibernation
Jet Propulsion Laboratory
March 31, 2010

MARS EXPLORATION ROVER MISSION STATUS REPORT

PASADENA, Calif. -- NASA's Mars Exploration Rover Spirit skipped a
planned communication session on March 30 and, as anticipated from
recent power-supply projections, has probably entered a low-power
hibernation mode.

In this mode, the rover's clock keeps running, but communications and
other activities are suspended in order to put all available energy into
heating and battery recharging. When the battery charge is adequate, the
rover attempts to wake up and communicate on a schedule it knows.

"We may not hear from Spirit again for weeks or months, but we will be
listening at every opportunity, and our expectation is that Spirit will
resume communications when the batteries are sufficiently charged," said
John Callas of NASA's Jet Propulsion Laboratory, Pasadena, Calif., who
is project manager for Spirit and its twin rover, Opportunity.

Spirit's power supply is low because daily sunshine for dusty solar
panels is declining with the approach of the winter solstice, in
mid-May, in Mars' southern hemisphere. In the three previous Martian
winters that Spirit has survived since landing in January 2004, the
rover was tilted northward to put its solar panels at a favorable angle
toward the sun. That preparation was not possible this winter because of
impaired mobility. Spirit's wheels are dug into soft sand, and the rover
lost the use of a second wheel four months ago. It had previously lost
use of one of its six wheels four years ago.

Spirit's original mission was planned to last for three months. The
rover has worked extended missions since April 2004. Opportunity is
currently on a long-term trek toward a large crater named Endeavour.

Spirit had been communicating on a once-per-week schedule in recent
weeks. During the designated time for the rover to communicate with
NASA's Mars Odyssey orbiter passing overhead on March 30, Odyssey heard
nothing from the rover.

"We are checking other less-likely possibilities for the missed
communication, but this probably means that Spirit tripped a low-power
fault sometime between the last downlink on March 22 and yesterday,"
Callas said. "The recent downlinks had indicated that the battery state
of charge was decreasing, getting close to the level that would put
Spirit into this hibernation."

In coming weeks, Spirit's core electronics will become colder than any
temperature they have ever experienced on Mars. Thermal projections
indicate the temperature probably will not drop lower than the
electronics were designed and tested to tolerate, but the age of the
rover adds to the uncertainty of survival.

"The temperature limit was for a new rover. We now have an older rover
with thousands of thermal cycles on Mars, so the colder temperatures
will be a further stress," Callas said. JPL, a division of the
California Institute of Technology in Pasadena, manages the Mars
Exploration Rover Project for NASA's Science Mission Directorate,
Washington. For more information about the Mars rovers, visit
http://www.nasa.gov/rovers .

Guy Webster 818-354-6278
Jet Propulsion Laboratory, Pasadena, Calif.
guy.webster at jpl.nasa.gov

2010-106
Received on Wed 31 Mar 2010 07:41:07 PM PDT