ITHACA, N.Y., June 17 (UPI) -- Six years after landing on Mars, the rover Spirit is bogged down in Martian soil, researchers at Cornell University said, but Opportunity carries on.
"The vehicle (Spirit) seems to be in a unique combination of soft, sandy material and slopes that we haven't encountered yet," said Jim Bell, professor of astronomy and leader of the mission's Pancam color camera team.
"We're not calling this purgatory for Spirit yet, but it has that potential," Bell said.
Spirit and its twin, Opportunity, have continued operating years after their predicted operational lifespan.
Spirit is stuck in Gusev crater, while Opportunity is on the other side of the planet ending a two-year exploration of Victoria Crater, which showed Mars once had water, Bell said.
Opportunity next heads south to Endeavor crater, 8.5 miles away, said Steve Squyres, Cornell professor of astronomy and the principal investigator for NASA's Mars Exploration Rover mission.
"We're living on borrowed time. But we're pushing onward as hard as we can," Squyres said of both rovers.