Just recently, a study determined that it may be impossible to find life on Mars via its polar ice caps, but hope has sprung forth again in an unusual form: Martian “cauliflowers”.
In 2008, NASA’s Spirit rover stumbled upon something strange in Mars’ Gusev Crater. The crater—which is believed to have once housed hot springs and geysers—was covered in innumerous tiny, cauliflower-shaped nodules of a mineral known as opaline silica.
Opaline silica is a pretty common mineral in and of itself. On Earth, it can become widely distributed throughout soil and water via the weathering of silicate minerals, and some organisms, like diatoms, need it to live.
But finding opaline silica shaped like little trees on Mars left many scratching their heads, wondering how the mineral deposited in that shape.
Alien life
New research by Steven Ruff and Jack Farmer of Arizona State University in Tempe, however, has an exciting proposal for where these “micro-digitate silica profusions” (as they as also more scientifically known) came from. After examining similar mineral deposits in a Chilean desert, the pair has offered the notion that the “cauliflowers” were shaped by microbes—suggesting that alien life may have existed on Mars at some point.
As outlined at the American Geophysical Union Fall Meeting in December, the pair studied Chile’s Atacama Desert, which has conditions that make it fairly analogous to the surface of Mars: the soil is similar; the extreme desert climate (less than four inches of rain per year, plus temperatures that range from -13 to 113 degrees Fahrenheit) is similar; and the huge amount of ultraviolet radiation that penetrates to the ground (thanks to its elevation of 13,000 feet about sea level) all make it probably the closest thing we have to Mars on Earth.
Of course, Atacama Desert has oxygen and living organisms, but since scientists can’t swing by Mars whenever they wish to pick up some samples, so we work with what we have.
But besides the similarity in environment, Atacama has another huge similarity to Gusev Crater: It used to house geysers, too, and in fact has incredibly similar looking silica deposits. Further, there is fossil evidence that its geysers used to be home to many different kinds of microbes.
These microbes are believed to have given the “cauliflowers” in Atacama Desert their shape, as similar silica deposits have also been seen in Yellowstone National Park and in New Zealand’s Taupo Volcanic Zone—modern places where the little formations showed fossilized proof of having been created by microbes.
In Atacama Desert’s case, the fossil evidence is less clear, and it is uncertain whether or not the organisms are responsible for the silica cauliflowers. However, the case is compelling, and points to the fact that the ones found on Mars may very well have been created by living creatures.
But analogy is by no means proof.
“Having worked on modern hot springs, I have seen all forms of structures that look biological but are not,” Kurt Konhauser of the University of Alberta, who is the editor-in-chief of the journal Geobiology, told Smithsonian Magazine. “Because it looks biological doesn’t mean it is.”
We will have to wait a while to find out whether the silicate formations are life or luck, though. The next rover isn’t due to launch until 2020, and once it does, it will have to reach Mars, spend time collecting samples, and then travel all the way home before we can get our hands on real samples—that is, if NASA decides to spend time investigating the cauliflowers at all. Gusev Crater hasn’t been ruled out as a landing site, but it might not be selected at all.
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Feature Image: NASA/JPL-Caltech
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