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Nasa's evergreen Mars rover Opportunity keeps on rolling

8 December 2011 Last updated at 10:18 GMT

Creaking and arthritic it may be, but Nasa's Mars rover Opportunity continues to deliver remarkable science.

The near-eight-year-old mobile geologist has just found slivers of a bright material that looks very much like it is gypsum (hydrated calcium sulphate).

If confirmed, it would be the most unambiguous signal of water activity yet found on Mars by this mission which manages to keep on rolling.

Lead scientist on the mission Steve Squyres gave BBC science correspondent Jonathan Amos an update on the rover.