Mission News

Unexpected Wheel-Test Results
12.15.09
 
Slight Movement by Spirit's Right-Front Wheel, Sol 2113 Rover Spirit during the rover's 2,113th Martian day, or sol (Dec. 12, 2009). Image Credit: NASA/JPL-Caltech
› Full image and caption

Diagnostic tests were run on Spirit's right-rear wheel and right-front wheel on Sol 2113 (Dec. 12, 2009). The right-rear wheel, which stalled during a drive two weeks earlier, continued to show no motion in the latest tests and exhibited very high resistance in the motor winding. The right-front wheel, which stopped operating on Sol 779 (March 13, 2006), surprised engineers by indicating normal resistance and turning slightly during a resistance test for that wheel.

Small motion is expected during an electrical resistance test for an operating actuator, but the right-front actuator was expected to be non-operational. The right-front wheel was last checked just after its apparent failure in 2006 and at that time indicated an open circuit. Although no clear theory for failure had been established, the failure was generally regarded as permanent. It is important to remember that the Sol 2113 test of the right-front wheel was only a rotor resistance test, and no conclusions can be drawn at this point without further testing.

The plan for Spirit on Sol 2116 (Dec. 15) is to command a drive. This drive will further investigate functionality of the right-front and right-rear wheels. The results are expected Wednesday.

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

Dwayne Brown 202-358-1726
NASA Headquarters, Washington
dwayne.c.brown@nasa.gov

2009-197