The Mars rover Spirit is putting down roots.
After months of trying to wiggle the rover out of a sand trap on Mars, the NASA probe remains firmly entrenched in the soft soil inside a small crater.
So mission managers announced Tuesday that the rover will stay put, spending the rest of its days conducting science from its current location inside the crater, where its wheels can move only a few inches.
That crater proved to be "a golfer's worst nightmare," Doug McCuistion, director of the Mars Exploration Program, told reporters Tuesday at a press briefing in Washington, D.C.
"It's a sand trap that, no matter how many strokes you take, you just can't get out."
Video: Stuck Mars Rover About to Die? (January 5, 2010)
Now, instead of planning an escape, rover drivers will use the craft's limited mobility to reposition the probe, giving Spirit a better chance of surviving the oncoming Martian winter.
"In the past we've been able to drive the rover to tilt its solar arrays toward the north and maximize sunlight," said rover project manager John Callas, based at NASA's Jet Propulsion Laboratory (JPL) in Pasadena, California.
Right now Spirit has "an unfavorable tilt," about nine degrees toward the south, he said.
"If we can't improve the tilt, we'll drop below the power levels we need to maintain daily activities."
In that case, the rover would trigger itself to go into hibernation, and NASA mission managers likely wouldn't hear a peep out of the craft for about six months.
In the meantime, mission managers will continue to communicate with Spirit's twin rover, Opportunity, which is currently motoring toward Endeavour Crater.
Opportunity "is now on approach to an extremely young crater called Concepcion [which] may be the youngest crater a rover has yet encountered," McCuistion said.
No Guarantee Mars Rover Will Survive
Surviving the winter is the biggest challenge facing Spirit right now, Callas said.
"Normally we keep it warm by having it on," like a car running its engine on a cold day, he said.
During previous winters, when NASA parked the rover and maximized northward tilt, Spirit collected enough power to stay on and communicating until it could drive again in the spring.
But if Spirit goes into hibernation, any power collected by the solar panels will go into charging the battery, not warming the electronics.
The rover was designed to withstand temperatures down to -55 degrees Celsius (-67 degrees Fahrenheit) during hibernation, and Martian winter this year is expected to see lows around -45 Celsius (-49 Fahrenheit).
"That's within the design limits," Callas said. "But those limits were tested for a brand new rover fresh out of the box." Spirit, which was designed for a 90-day mission, has been roving Mars for the past six years.
"There's no guarantee Spirit will survive ... and an extended period not hearing from the rover will be frustrating."
Mars Rover's Future: Advancing Without Moving?
If Spirit does wake up in spring, the Mars rover team "will use the mobility system as best we can ... to make the full capabilities of the rover available to science," noted rover driver Ashley Stroupe, also of JPL.
For instance, having the rover stay put can reveal new insights into Mars's core, its atmospheric conditions, and its watery past, noted Steve Squyres, the rover mission's principle investigator, based at Cornell University.
"The imperative to drive is relaxed now, and we're able to focus on a whole new class of science," he said.
Tracking the rover's radio signal from its fixed position, for example, will allow astronomers to finely calculate the way Mars wobbles as it spins on its axis.
Like a raw egg versus a hard-boiled one, the planet should wobble differently on its axis if its metal core is solid than if it's molten. (Related: "Mars's Liquid Center Cooling in Unusual Manner, Study Suggests.")
Scientists can also direct the rover's robotic arm to take multiple soil samples from different locations around the crater, allowing them to measure how Mars's atmosphere interacts with its surface over time.
And the sand trap Spirit is stuck in presents its own opportunities: The crater is filled with unusual layers of sulfate salts, minerals that hint at relatively recent water action on Mars.
"The bottom line is, we're not giving up on Spirit," Squyres said. "I feel there's a lot of really exciting science ahead, including some stuff that I think is truly groundbreaking."