NASA-International Space Station

NASA Sunday celebrated Mars rover Spirit's bountiful, six-year period on the red planet, way longer than the three months it was forecast to last. But it all might soon come to an end, stuck as it is in Martian sand.

All attempts to remove it have failed so far. The last time, in November, not only did the robot not budge from its place, but its right rear wheel broke down. Its right front wheel stopped working in 2006 most likely due to a worn out electric motor.

Dead in its tracks, Spirit cannot shake off the Martian dust that is gradually accumulating on its solar panels, preventing its batteries from recharging.

Unless the wind blows the dust away or, in a spurt of energy, Spirit can shift its inclination to better point the panels toward the sun, "the quantity of sunshine available will continue to decline until (the Martian solstice) May 2010," NASA said on its website.

That means "Spirit may not have sufficient power to remain in operation" during the Martian winter, the space agency added. Despite its predicament, Spirit has been able to carry on its scientific work and has even made an astonishing discovery.

As its wheels spun and churned up the ground in its attempt to break free of the sand trap, it exposed traces of sulfates underneath, scientist Ray Arvidson, of the Washington University in St. Louis, Missouri, said last month.

"Sulfates are minerals just underneath the surface that shout to us that they were formed in steam vents, since steam has sulfur in it. Steam is connected with hydrothermal activity -- evidence of water-charged explosive volcanism."Such areas could have once supported life," he said.

Spirit and its twin rover, Opportunity which landed on the contradictory side of Mars three weeks later than Spirit, on January 24, 2004 have been given 90 more days of mission time. Scientists are not too certain the Martian wind will be able to dust off their power-generating solar panels.