Dust storms are currently stirring up the Martian skies in the region where NASA's Spirit rover is stuck in the sand. The swirling sands don't pose an immediate threat to Spirit, but they could create more urgency for the effort to free the mired rover if dust obscures her access to solar energy.
Spirit has been stuck in Martian dirt up to its hubcaps since May 6, when it became mired in a dirt patch (now called "Troy") while driving backward.
Engineers back on Earth have been using working replicas of the rover to test out ways to maneuver Spirit out of the sand trap.
So far, time has been on the team's time, as Spirit has plenty of energy ever since her solar arrays got cleaned off by winds a few months ago.
There's no immediate threat to Spirit's power levels from a darkened, dust-filled sky, as the rover has plenty of reserves and rover handlers are being conservative with their energy use, said project manager John Callas. But when the winds abate, they may have a problem, as the dust will then start falling back to the Martian surface.
"If the dust is raining out of the skies, it will build back up on the solar arrays," Callas said. This could become a problem during the next Martian winter, when the sun is low in the sky and generally making it difficult to keep power supplies up.
The dust should start falling out in a matter of days, and though scientists can only estimate how much dust has been whipped up into the atmosphere, "it does seem like there's a lot of dust in the air," Callas said.
The dust storm won't have any effect on Spirit's dug in-position, Callas said. While the winds of the storm will push around dirt particles — sometimes enough to obliterate rover tracks — it only amounts to "a very thin veneer of surface material," Callas told SPACE.com.
Callas and his team are still using the replica rovers to test out scenarios for moving Spirit, which they plan to start doing in September.
The team is using two different test rovers — a heavier, engineering model that has all the same instruments as Spirit and its twin, Opportunity, and a lighter model that more accurately simulates the weight of the rovers in Mars' lower gravity. The pair of rovers have been on Mars for more than five years now.
The engineers are also trying out rover moves in two different types of sand: one lighter, flour-like material that represents a "worst-case scenario" because it provides little traction, and one coarser material that represents a "best-case scenario" because it has more bearing strength and provides more traction, Callas explained.
With the data from testing both rovers in both types of material, the rover engineers will have a better idea of what might work best on Mars. In a week or so, they'll do a dress rehearsal, in which they move one of the test rovers all the way through the sequence that's planned for use on Mars.
If the test goes well, they'll try the maneuvers out with Spirit herself.
The potential dust deposits increase the urgency of getting Spirit out, Callas said, because if her solar arrays become blocked, they'll have to find a good winter haven — and the sooner the better.
"We all want to get out; we all want to get moving again," Callas said.