Washington, Jan 2 (IANS) The Martiain winter might end NASA’s beloved space rover Spirit’s romps as it completes six years of unprecedented exploration Sunday.
Spirit successfully landed on the Red Planet at 8.35 p.m. Pacific Standard Time Jan 2, 2004 and its twin Opportunity arrived at 9.05 p.m. 22 days later.

The rovers began missions intended to last for three months but have lasted six years, or 3.2 Mars years.

The Spirit has found evidence of a steamy and violent environment on Mars that was quite different from the wet and acidic past documented by Opportunity, which has been operating successfully as it explores halfway around the planet.

A sand trap and balky wheels are challenges to Spirit’s mobility that could prevent NASA’s rover team from using a key survival strategy for the rover.

The team may not be able to position the robot’s solar panels to tilt toward the sun to collect power for heat to survive the severe Martian winter.

Nine months ago, Spirit’s wheels broke through a crusty surface layer into loose sand hidden underneath.

Efforts to escape this sand trap barely have budged the rover. The rover’s inability to use all six wheels for driving has worsened the predicament.

Spirit’s right-front wheel quit working in 2006, and its right-rear wheel stalled a month ago. Surprisingly, the right-front wheel resumed working, though intermittently.

Drives with four or five operating wheels have produced little progress toward escaping the sand trap. The latest attempts resulted in the rover sinking deeper in the soil.

“The highest priority for this mission right now is to stay mobile, if that’s possible,” said Steve Squyres of Cornell University in Ithaca. He is the principal investigator for the rovers.

If mobility is not possible, the next priority is to improve the rover’s tilt, while Spirit is able to generate enough electricity to turn its wheels, said a NASA release.

Unless the tilt can be improved or luck with winds affects the gradual buildup of dust on the solar panels, the amount of sunshine available will continue to decline until May 2010. During May, or perhaps earlier, Spirit may not have enough power to remain in operation.

“Spirit could continue significant research right where it is,” said Ray Arvidson of Washington University in St. Louis, deputy principal investigator for the rovers.

“We can study the interior of Mars, monitor the weather and continue examining the interesting deposits uncovered by Spirit’s wheels.”