Spirit Mars Rover: Unexpected Wheel-Test Results

December 15, 2009
Diagnostic tests were run on Spirit's right-rear wheel and right-front wheel on Sol 2013 (Dec. 12, 2009). Image Credit: NASA/JPL-Caltech (Click Enlarge for animation)

(PhysOrg.com) -- Diagnostic tests were run on Spirit's right-rear wheel and right-front wheel on Sol 2013 (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 was generally regarded as permanent. It is important to remember that the Sol 2013 test of the right-front was only a rotor resistance test, and no conclusions can be drawn at this point without further testing.

The plan for Spirit on 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.

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DGBEACH
4 / 5 (1) Dec 16, 2009
A high resistance reading on a motor coil would mean that there was a break in the wire of the coil. However, the two "ends" could still be close enough to each other that there would be intermittent conduction upon expansion or contraction of the coil due to temperature changes, or if there were enough motion to jostle them together. Either way, it would only be for brief amounts of time. They should definitely NOT get their hopes up on this one!
Rdavid
Dec 16, 2009
This comment has been removed by a moderator.
PPihkala
not rated yet Dec 16, 2009
The whole unit of Spirit had an planned life time of three months. It has worked past that time many times over. Not everything works anymore, but that's to be expected. Maybe in the next iteration they can design a better device taking measures to mitigate the effect of different failures.

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