NASA tries to free stuck Mars rover

LOS ANGELES — For NASA’s stuck Mars rover, the Spirit may be willing, but the wheels could prove too weak.

The space agency on Thursday outlined a rescue plan to try to free the rover Spirit, which has been bogged in a sand trap on the red planet for half a year. The risky operation is expected to last several months.

“If it cannot make the great escape from this sand trap, it’s likely that this lonely spot straddling the edge of this crater might be where Spirit ends its adventures on Mars,” said Doug McCuistion, who heads the Mars exploration program at NASA.

The rover was driving backward in April when its wheels broke through the crusty surface and became mired in a patch of talcum-like dirt. It tried to crab its way out, but sunk deeper.

After rehearsing various escape tries on Earth using prototype rovers, NASA said it was finally ready to provide some roadside assistance on Mars.

The first driving commands will be sent to Spirit on Monday, but engineers cautioned the wheels likely will have high slippage.

The plans calls for Spirit to drive forward and retrace its steps. “If we follow our old tracks out, we may be able to make better progress,” a rover driver said.

Spirit landed on Mars with six working wheels but soon lost movement in its right front wheel. It had been rolling around the red planet dragging the gimpy wheel before it got stuck.

To complicate matters, images snapped by the rover show rocks pushing up against its underbelly, which could make it harder for the wheels to get traction.