Mars Rover's Unexpected Behavior Puzzles NASA

An image of Mars from the rover Spirit taken from a low Martian plateau called “Home Plate”, which is 260 feet in diameter.
This view is from the spot where Spirit has spent its third Martian southern-hemisphere winter in 2008, on the northern edge of a low plateau informally called "Home Plate." A dotted line marks the edge of Home Plate, which is about 80 meters or 260 feet
(Image: © University/NMMNHS)

Thisstory was updated on Jan. 29 at 8:52 a.m. EST.

NASA engineers are scratching their heads over someunexpected behavior from the long-lived Spirit rover, which began its sixthyear exploring Mars this month.

Spirit failed to report in to engineers at NASA?sJet Propulsion Laboratory (JPL) in Pasadena, Calif., last weekend, prompting aseries of diagnostic tests this week to hunt the glitch?s source. The agingMars rover did not beam home a record of its weekend activities and, morepuzzlingly, apparently failed to even record any of its actions on Sunday,mission managers said.

"We don't have a good explanation yet for theway Spirit has been acting for the past few days," said NASA?s Sharon Laubach, who leads the JPL team that that writes and checkscommands for the rover and its robotic twin Opportunity. "Our next stepswill be diagnostic activities."

Sundaymarked Spirit?s 1,800th Martian day, or sol, exploring a regionknown as "Home Plate" in the planet?s expansive Gusev Crater.

Spiritand its twin Opportunity were initially expected to spend just 90 daysexploring the Martian surface when they landed in succession morethan five years ago this month. Opportunity is currently headed for the monstercrater Endeavour on the other side of Mars.

OnSunday, Spirit apparently received commands to drive to its next waypoint, butfailed to move an inch, mission managers said.

Whilethat glitch can have any number of causes, such as Spirit not properlyperceiving it was ready to drive, the rover?s failure to record its daily workin its non-volatile computer memory is perplexing, they added.

ByMonday, Spirit?s mission controllers decided to tell the rover to find the sunwith its camera on Tuesday to determine its location on Mars. Early Tuesday,the rover beamed back that it had tried to follow the instructions of its humanhandlers and did find the sun, but not in the location it expected the star tobe in.

NASAengineers believe Spirit?s woes may be due to a transitory cause, such as ahigh-energy cosmic ray hitting the rover?s electronics. On Tuesday, the rover?snon-volatile memory appeared to be working fine, mission managers said.

Therovers Spirit and Opportunity have lasted more than 20 times their initialthree-month mission plan, with each suffering from aches and pains associatedwith their longevity.

Spiritinitially bounced back from a worrying computer glitch early in its mission andhas since survivedfrigid winters on Mars and scaled a nearby hill. Both rovers have expandedscientists? knowledge of the history of liquid water on Mars during theirrespective missions.

Whilepuzzling, Spirit?s new glitches don?t appear to be a serious concern atpresent, according to NASA?s rover mission chief John Callas.

"Right now, Spirit is under normal sequencecontrol, reporting good health and responsive to commands from theground," he added.

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