By Sarah Scoles
Unusual silica formations spotted by a NASA rover look
a lot like structures formed by microbes around geysers on Earth
The hunt for signs of life on Mars has been on for decades, and so far scientists have found only barren dirt and rocks. Now a pair of astronomers thinks that strangely shaped minerals inside a Martian crater could be the clue everyone has been waiting for.
In 2008, scientists announced that NASA’s Spirit rover had discovered deposits of a mineral called opaline silica inside Mars’s Gusev crater. That on its own is not as noteworthy as the silica’s shape: Its outer layers are covered in tiny nodules that look like heads of cauliflower sprouting from the red dirt.
No one knows for sure how those shapes—affectionately called “micro-digitate silica protrusions”—formed. But based on recent discoveries in a Chilean desert, Steven Ruff and Jack Farmer, both of Arizona State University in Tempe, think the silica might have been sculpted by microbes. At a meeting of the American Geophysical Union in December, they made the case that these weird minerals might be our best targets for identifying evidence of past life on Mars. […]