When the Opportunity rover landed on Mars last year, scientists were thrilled that it made a cosmic "hole-in-one" by rolling into a crater.
But now the robot is struggling to drive itself out of a sand trap. Time will tell whether it's up to par for the task.
Progress is being made on trying to remove Opportunity from a soft-sand dune that the sporty, six-wheeled utility rover has run itself into at its exploration site: Meridiani Planum.
And on Mars, there are no tow trucks, at least not yet. So who are you going to call?
Dune field dilemma
"We're going to be ready soon to start making our move at Meridiani," said Steve Squyres, lead scientist from Cornell University for the Mars Exploration Rover (MER) effort.
Squyres noted on a Cornell web site devoted to the MER project that a long hard week of testing was undertaken at NASA's Jet Propulsion Laboratory (JPL) in Pasadena, California.
At JPL, engineers, scientists, outside advisors, and even the project manager have been mixing sandy and powdery materials, digging holes and building dunes - all in an attempt to figure out how best to get Opportunity out of its dune field dilemma.
The team is also busily working on why the robot dug itself into the small dune, and what added safety-in-driving tips to follow in the future.
The blend of sandy and powdery material brought in for testing purposes matched the way the soil has worked itself into spaces between the cleats on Opportunity's wheels.
"We tested with one mix of materials, decided it wasn't quite nasty enough, and then made the mix nastier and tested again. We tested getting the rover stuck and then unstuck in a bunch of different configurations, some of which we think were worse than the one we've gotten ourselves into on Mars," Squyres explained.
"The goal of this kind of testing is to be 'conservative'... to test under conditions that are at least as bad as -- and preferably worse than -- what you're dealing with in reality," Squyres observed.
Soon it will be time to put to practice what the tests have shown, Squyres said. "We've learned quite a bit," he said, pointing out that it can take a lot of rover wheel turns to move the Mars machine from a configuration like the one in which it now finds itself.
"And while it's tempting to go for it all in one shot, the smart approach is to be cautious about it and do the job in small steps. So that's what we're going to do," Squyres added. Moving soil bit by bit beneath Opportunity's wheels, to enable the extraction process, is going to take time, he concluded.
Is it too dangerous to press forward, perhaps better to have Opportunity backtrack and head for safer ground?
"Why go forward? You could have asked us that question at the beginning of the mission...before we even launched the rovers," Squyres responded to SPACE.com. "You go forward because the easy stuff has been done."
Squyres said that the rover science team has looked at the plains, down into little craters, and know what a lot of Meridiani Planum is like.
"You don't succeed in a mission like this just by keeping the rover alive and staying out of trouble. You succeed by pushing hard and finding new things," Squyres related. Before Opportunity reached the etched terrain in which it now sits, the scientist did caution that this landscape might turn out to be some impenetrable barrier.
"And who knows, maybe it will be. But we were prepared for that. The risks involved in exploring the etched terrain are part of why we spent so much time at Endurance Crater. We had a scientific gold mine there, and we wanted to work it for all it was worth before taking a risk in the etched terrain," Squyres emphasized.
While Opportunity and Earth controllers have hit their first impediment, Squyres stressed it's forward ho for now.
"You work to overcome it, and then you move on. But are we going to back away from unknown territory on the horizon, back to the safe stuff we know, because we've hit one obstacle? Hell no," Squyres said. "If it becomes clear that we really can't drive in this stuff, under any circumstances, then yeah, it'll be time to find another way to use the vehicle. But we're nowhere near that point right now."
While rover operators work out the plan of action, Opportunity is imaging the plains of Meridiani Planum and performing atmospheric science observations.
In the meantime, on the other side of Mars, the Spirit rover continues its study of the Columbia Hills within Gusev Crater.
- Rover Special Report