Probable Traces of Hot Springs or Steam Vents on Mars

While researchers try to find a spot for the limping Mars Spirit Rover to spend the winter, they're also puzzling over one of the mission's most significant finds yet.

Pictured here is a patch of bright soil discovered by Spirit last May, which boasts a nearly pure concentration of silica. Researchers have two theories about what could have created the effect, either one potentially fascinating.

In one theory, it might have come from a hot spring, which deposit materials before drying up. Alternately – and most likely, researchers say – it could be evidence of a fumerole, in which acidic steam rises through cracks in the surrounding rock.

Either way, it's exciting. On Earth, both of those environments typically host vibrant microbial life – and on Mars, the formation could potentially be home to microscopic fossils proving that the planet once had life of a kind. Here's the researchers themselves:

"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 Mars in the past," said Steve Squyres of Cornell University, Ithaca, N.Y., principal investigator for the rovers' science payload. "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."

NASA scientists are worried about Spirit's survival through the upcoming winter. Storms this year left the rover with considerable dust on its solar panels, which will require it to be stationary in a relatively sunny spot through the long winter.

Mars Rover Investigates Signs of Steamy Martian Past [NASA press release]

(Image: The silica-rich patch discovered by the Spirit Rover earlier this year. Credit: NASA/JPL/Cornell)