Mars and Earth Activities Aim to Get Spirit Rolling Again

MEDIA RELATIONS OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIFORNIA 91109. TELEPHONE 818-354-5011
http://www.jpl.nasa.gov

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

Mars Exploration Rover Mission Status Report May 18, 2009

Mars and Earth Activities Aim to Get Spirit Rolling Again

PASADENA, Calif. -- NASA's rover project team is using the Spirit rover and other
spacecraft at Mars to begin developing the best maneuvers for extracting Spirit from the
soft Martian ground where it has become embedded.

A diagnostic test on May 16 provided favorable indications about Spirit's left middle
wheel. The possibility of the wheel being jammed was one factor in the rover team's May 7
decision to temporarily suspend driving Spirit after that wheel stalled and other wheels had
dug themselves about hub-deep into the soil. The test over the weekend showed electrical
resistance in the left middle wheel is within the expected range for a motor that has not
failed.

"This is not a full exoneration of the wheel, but it is encouraging," said John Callas of
NASA's Jet Propulsion Laboratory, Pasadena, Calif., project manager for Spirit and its
twin rover, Opportunity. "We're taking incremental steps. Next, we'll command that wheel
to rotate a degree or two. The other wheels will be kept motionless, so this is not expected
to alter the position of the vehicle."

Another reason to suspend driving is the possibility that the wheels' digging into the soil
may have lowered the body of the rover enough for its belly pan to be in contact with a
small mound of rocks. The rover team is using Opportunity to test a procedure for possible
use by Spirit: looking underneath the rover with the microscopic imager camera that is
mounted on the end of the rover's arm. This might be a way to see whether Spirit is, in fact,
touching the rocks beneath it.

NASA's Mars Odyssey orbiter is also aiding in the Spirit recovery plan. As a result of
winds blowing dust off Spirit's solar panel four times in the past month, Spirit now has
enough power to add an extra communication session each day. The Odyssey project has
made the orbiter available for receiving extra transmissions from Spirit. The transmissions
include imaging data from Spirit's examinations of soil properties and ground geometry.

Rover team members are using that data and other information to construct a simulation of
Spirit's situation in a rover testing facility at JPL. The team is testing different materials to
use as soil that will mimic the physical properties of the Martian soil where Spirit is
embedded. Later, the team will test maneuvers to get the rover free. Weeks of testing are
anticipated before any attempt to move Spirit.

JPL, a division of the California Institute of Technology in Pasadena, manages the Mars
Exploration Rover project for NASA's Science Mission Directorate, Washington.

#2009-087

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