Our Brave Explorer: Spirit.

You’d have to be under a rock for the past 6 years to not know of the great successes of the Mars rovers Spirit and Opportunity. Initially only designed for a maximum operation of 90 days they have shown what good engineering and a little bit of luck can do for you as they’ve been running almost non-stop since they landed. They haven’t been without their share of troubles however with both of them becoming stuck in Mars’ unusual terrain at one time or the other. More recently however Spirit has been stuck at a point called Troy, which basically amounts to a typical sand trap with a rock in the middle of it. Here’s a little background on the situation:

The rover drove into soft ground a couple of weeks ago, and when it tried to get out, its wheels slipped and it moved only a couple of inches.

The Spirit has been stuck before, and mission managers have been assiduously driving it around potential hazards. But they did not see the soft spot, which was hidden under a veneer of normal-looking soil.

“It is quite serious,” said John Callas, the project manager for the Spirit and the Opportunity, its twin rover on the other side of Mars.

Steven W. Squyres, the principal investigator of the rover mission, said the material looked like ferric sulfate salt, which had previously been encountered. “From a rover mobility standpoint, it is insidious stuff,” he said. “This stuff has very little cohesion. What this means is that it’s very tough for the rover wheels to get a grip on it.”

Following the rover’s situation over at the NASA Free Spirit website shows that this initial report was indeed true. They began extraction attempts well over a month ago and progress has been extremely slow. If you have a look at any of the pictures over at their site you’ll see why, it’s pretty much wheel deep on all sides bar one which means it has very little traction. Compounded with the fact that the wheels weren’t really designed with this kind of surface in mind (the wheels would’ve been a lot larger and wider if they tried to compensate for this kind of terrain) we’re in for a long an arduous extraction process. Opportunity took about 3 months to extract itself out of a lesser situation, and had all of its wheels working.

Still it seems that despite its difficult situation the rover team is making the best of it. The rovers don’t really spend much time in any one spot and they rarely get themselves into a situation where they’re digging more than an inch into the martian soil. As it turns out all this wheel spinning has managed to break through the thin top crust and liberate some of the deeper down soil, with some very interesting results:

Spirit broke through a dark reddish-brown crusty surface that was an inch or so thick, exposing loose, sandy material. As the rover tried to break free, its wheels began to churn the soil, uncovering even more sandy material, bearing “a higher concentration of sulfate that seen anywhere else on Mars,” Arvidson said.

“Sulfates are minerals just beneath the surface that shout to us that they were formed in steam vents or hydrothermal pools, since hot water associated with these systems has sulfur in it,” he explained. “These deposits are evidence of water-charged explosive volcanism. Such areas could have once supported life.”

“Also, the robot found that the top of the sulfate material is crusty,” Arvidson added. “Ancient sulfates probably formed this crust as they were processed by variations in climate associated with changes in Mars’ orbit over millions of years.”

That’s pretty exciting stuff right there and it just adds more credence to the theory that Mars was once a potential home to life and could quite possibly have been quite similar to our own blue marbel. It’s discoveries like these that have influenced projects such as the Mars Science Laboratory, which will answer these questions with much greater detail.

It’s not all bad news for Spirit however, they recently gave all wheels a diagnostic test to see what their condition was like. Although it was a long shot they decided to include the supposedly dead wheel a go as well, figuring that it was a long shot but could pay off big should it respond. To everyone’s surprise it did and whilst it’s not 100% conclusive that the wheel is ready, willing and able it does mean there’s a small glimmer of hope on the horizon for extracting Spirit out of Troy before it freezes to death in the martian winter.

Maybe we’ll see some traction (snicker) in the new year 🙂

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