Original URL: http://www.theregister.co.uk/2009/01/29/rover_erratic_behaviour/

NASA ponders Spirit's erratic behaviour

Mars rover showing its age?

By Lester Haines

Posted in Science, 29th January 2009 11:24 GMT

The team controlling NASA's Mars rover Spirit is planning to carry out some diagnostic tests on the venerable vehicle after it earlier this week indulged in some "unexplained behavior", as the agency puts it.

On Sunday, Spirit reported that it had "received its driving commands for the day but had not moved" - a correct decision if it didn't know its orientation. Accordingly, NASA on Tuesday commanded the rover to re-establish its bearings by pinpointing the sun with its camera.

Spirit later confirmed it had located the sun, "but not in its expected location".

What's further baffling NASA boffins is that Spirit didn't record Sunday's main activities "into the non-volatile memory", which preserves data even when the power's off. They suggest one possible cause of this are "transitory effects from cosmic rays hitting electronics", although they're really not sure what's going on.

Sharon Laubach, head of the team that writes and checks the rover's commands, admitted: "We don't have a good explanation yet for the way Spirit has been acting for the past few days."

The wobbly rover has, though, now made a full recovery. Project manager John Callas said yesterday: “Right now, Spirit is under normal sequence control, reporting good health and responsive to commands from the ground."

Spirit landed in the Red Planet's southern hemisphere on 3 January 2004, and has far outperformed its initial mission target of three months.

Earlier this month, the rover was dispatched to "a pair of destinations about 183 meters (200 yards) south of the site where Spirit spent most of 2008".

NASA explained: "One is a mound that might yield support for an interpretation that a plateau Spirit has studied since 2006, called Home Plate, is a remnant of a once more-extensive sheet of explosive volcanic material. The other destination is a house-size pit called Goddard."

Goddard, the agency elaborated, "might be a volcanic explosion crater, and that's something we haven't seen before". ®