Mars Exploration Rovers Still Going Strong

Although well past their 90-day "waranty" lifetime, the Spirit and Opportunity Mars Exploration Rovers (MERs) are still going strong. Opportunity continues to study Endurance crater and recently imaged wispy clouds in the Martian atmosphere. Since Spirit's right-front wheel continues to draw more current than normal, mission controllers have begun testing a process called "visual odometry" to track the rover's travels in case it needs to move about using only five of its six wheels.

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