The Mars rover Spirit is driving again this week after the ageing craft suffered a mysterious bout of forgetfulness.
Spirit鈥檚 controllers are still not sure what happened to the rover on 25 January, when the craft did not perform the day鈥檚 instructions, which included a short drive.
The rover also seemed to suffer amnesia, as it failed to record its activities in its 鈥渘on-volatile memory鈥�, which is used to store data when the rover is powered down.
Advertisement
There is no explanation for the behaviour, but Spirit has since performed normally.
鈥淎t this time, we don鈥檛 know whether the problem was a one-time event 鈥� whether it was induced by a cosmic ray 鈥� or whether it might be an indicator of ageing hardware,鈥� says project manager John Callas of NASA鈥檚 Jet Propulsion Laboratory in Pasadena, California. 鈥淲e鈥檙e staying vigilant and keeping an eye out, but right now Spirit鈥檚 back to where she was.鈥�
Getting its bearings
The team originally suspected the craft might not have moved because it was confused about its location, so on 27 January the team commanded the rover to orient itself by finding the Sun using just its panoramic camera.
Spirit pinpointed the Sun, but it was several degrees away from where the rover expected to find it. The team tracked down the source of the misalignment to a slight offset in the rover鈥檚 accelerometers, which are supposed to align with Mars鈥檚 gravity.
But the offset does not explain why the rover did not move. And it is not clear how long the rover has operated with the accelerometer glitch, since the last time Spirit performed the Sun-finding exercise 鈥渂lind鈥� 鈥� with just the camera to guide it and no assumptions about its orientation 鈥� was in 2004, Callas told New 杏吧原创.
Out of hibernation
The rover, which celebrated its fifth anniversary on the Red Planet in January, is emerging from hibernation after spending its winter parked on the northern slope of a plateau called Home Plate in Mars鈥� Gusev Crater.
Over the winter, the rover鈥檚 condition was temporarily classified as 鈥榮erious but stable鈥� after a dust storm caused the craft鈥檚 power levels to drop to an all-time low.
But enough sunlight is now hitting the rover鈥檚 solar panels to provide it with enough power for more than an hour of activity. On 31 January, the craft drove roughly 30 centimetres before its right-front wheel, which stopped turning in 2006, hit a partially buried rock. The team expects the rover will be able to circumvent the obstacle.
View images from Spirit鈥檚 five-year journey in this gallery of highlights from the twin rover missions.
