Interesting news from Mars
From the New York Times:
The lame wheel on the NASA Mars rover Spirit has proved an invaluable science tool, turning up evidence of a once habitable environment, scientists said Monday.
Since 2006, the Spirit has been driving backwards, due to a front wheel that won't turn. Last May, scientists noticed a bright spot in its tracks. They turned it around to look, and found high concentrations of silica. They tried to break open a rock, to see if it was silica all the way through, and although they failed, a neighboring rock did split, and it was rich in silica.
On Earth, such high concentrations of silica can form in only two places: a hot spring, where the silica is dissolved away and deposited elsewhere, or a fumarole, an environment, often near a volcano, where acidic steam rises through cracks. The acids dissolve other minerals, leaving mostly silica. On Earth, both environments teem with life.
As explained on the Mars Exploration Rovers website:
"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."