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Nasa engineers work on Spirit replica
A few months after it landed, Spirit's left front tyre began showing a problem by using much more energy than the others.
Here, Jet Propulsion Laboratory (JPL) engineers Eric Aguilar (left) and Joe Melko work in a sandbox to find a way around the problem. The wheel eventually died in 2006 but Nasa scientists were able to keep the rover rolling on five wheels by driving it backwards and devising easier ways to turn.
Photo credit: Nasa
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