Daily Updates - July 26, 2004
Spirit Status at end of sol 184 - 189
On sols 184 and 185, Spirit cycled heaters and attempted to lubricate the right front wheel's drive motor. Spirit also performed very short test drives. Spirit's orientation on "Engineering Flats" had the rover in a slight southerly tilt, away from the Sun. This low Sun angle, coupled with the power required to energize the heaters, put quite a strain on the batteries. The state of charge of the batteries after the test was very low, so science observations were not performed during these two sols.
On sol 186, Spirit used its instrument deployment device, or robotic arm, to validate a new front hazard-avoidance camera model. This new model will improve the positioning accuracy of the tools on the arm. The arm attempted to place the Moessbauer spectrometer at nine different locations. Seven targets were hit, and two targets were missed. The engineering team planned to repeat this operation on the two missed positions on a later sol. Spirit also performed a test drive to characterize the results of the lubrication activity. The beginning orientation of the vehicle had the right front wheel facing the Sun, so the starting temperature was much warmer than the original baseline test drive. This temperature difference makes it hard to accurately compare the pre and post test-drive results. Analysis indicates there is approximately a 20 percent increase in wheel drive performance, but engineers cannot attribute this gain to the four-sol wheel heating operation alone. Spirit sat mostly motionless for the about the last 30 sols, and that allowed some lubrication to re-flow naturally. The bottom line is that the right-front wheel's performance has improved, but it is still drawing about twice as much current as any other wheel.
After the tune-up, Spirit was free to begin its drive away from Engineering Flats and head to higher ground and a better solar orientation. On sol 187, with its batteries very low, Spirit limped 8 meters (26 feet) to a location with a slightly better tilt toward the Sun and performed about 50 minutes of science observations.
On sol 188, Spirit continued to drive away from Engineering Flats. As a strategy for dealing with the right-front wheel, Spirit is now driving backwards and dragging its right front wheel when it is on relatively flat terrain. This strategy aims to extend the lifetime of the wheel's drive motor for use when it is needed most. Spirit performed its first backward test drive of 4 meters (13 feet) on this sol. Spirit also performed about an hour and a half of remote-sensing observations using the panoramic camera, navigation camera and miniature thermal emission spectrometer.
On sol 189, which ended on July 15, Spirit's battery state of charge increased due to a better tilt of the solar arrays toward the Sun. Spirit performed a precision 6-meter (20-foot), 6-wheel drive, then drove another 3 meters (10 feet) doing the wheel drag. Spirit also imaged an interesting rock outcrop. The outcrop was directly beneath the vehicle and extending northward.
Total odometry after sol 189 is 3,450 meters (2.14 miles). Vehicle heading is 184.8 degrees.
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