NASA says its rover Spirit has discovered "the best evidence yet" of a past habitable environment on the planet's surface. Spirit found a patch of silica-rich soil earlier this year, which scientists believe is a promising sign that hosted at least niche environments that could have potentially harbored life. Spirit has been exploring a plateau called Home Plate, where it discovered silica-rich soil in May.
Researchers are now trying to determine what produced the patch of nearly pure silica. So far, they believe that the deposits must have come from an ancient hot-spring environment or a fumarole, in which acidic steam rises through cracks. On Earth, these types of environments are teeming with microbial life, said rover chief scientist Steve Squyres.
"Whichever of those conditions produced it, this concentration of silica is probably the most significant discovery by Spirit for revealing a habitable niche that existed on in the past," he said.
"The evidence is pointing most strongly toward fumarolic conditions, like you might see in Hawaii and in Iceland. Compared with deposits formed at hot springs, we know less about how well fumarolic deposits can preserve microbial fossils. That's something needing more study here on Earth."
Spirit and its twin rover Opportunity have remained on for much longer than originally planned. Their mission has been extended five times since they landed on opposite sides of the planet in January 2004. The rovers faced their biggest challenge this summer, when a series of dust devils blanketed their solar panels and restricted movement.
Winds finally cleaned off Opportunity, but Spirit is still covered in gunk, and is only working at 42 per cent capacity. NASA scientists said that Spirit will have a very difficult time reaching a resting spot for winter.
"Spirit is going into the winter with much more dust on its solar panels than in previous years," said NASA's John Callas, project manager for the rovers.
"The last Martian winter, we didn't move Spirit for about seven months. This time, the rover is likely to be stationary longer and with significantly lower available energy each Martian day."
Posted by Rebecca Sato
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Sources: NASA, The Telegraph