Rocks made by microbes
Scientists from the University of Arizona recently compared the structures in the photographs with stromatolites from Chile and found they were nearly identical. Stromatolites are rock formations formed by processes involving microbes. In humid environments they can form colonies which react to the calcium carbonate in water, forming limestone showing a layered structure which can date back billions of years.
The Chilean stromatolites are silica deposits from the high-altitude, icy El Tatio field. These formations of silicon oxide were formed by microbial life living around the geysers there. Based on the strong resemblance, the scientists believe that there must have been life on Mars.
Comparison of silica deposits from Mars (left) and El Tatio, Chile (right).
Wait and see
For the time being, whether the formations were in fact made by microbial life continues to be nothing more than speculation. It will only be possible to confirm the scientists’ suspicions if the rock can be examined on Earth. Unfortunately, Spirit became stuck and the other Mars landers are too far away. The next rover is not scheduled to be launched until 2020 so the suspense will continue for some time yet.
Another sign of life
In 2014 the Mars Exploration Rover Curiosity found methane on Mars. On Earth, 90% of this gas is produced by microorganisms and organisms. It is therefore increasingly likely that there was, or perhaps still is, life on Mars.
Source: Nature Communications