In its quest for signs of ancient microbial life on Mars, the NASA's Perseverance Rover has unearthed several fascinating pieces of information about the Red Planet. It landed on the Jezero crater in 2020 and has been since exploring the region. In its latest discovery, the rover has found that the floor of the crater, which once hosted a lake billion years ago, is made up of volcanic rocks rather than sedimentary rocks, as believed earlier. The rover started examining the floor in the spring of 2021, after which scientists studied the data. It was found that the floor was formed by two types of igneous rocks. While one type was formed deep underground from magma, the other was the result of volcanic activity on the surface.
According to Ken Farley of Caltech, Perseverance's project scientist, the igneous rocks collected from Mars can tell when the lake was present in Jezero. “We know it was there more recently than the igneous crater floor rocks formed,” said Farley. He added that the rocks will also help answer some major questions about Mars surrounding its climate, and conditions on it.
Igneous rocks are not considered ideal for preserving ancient signs of life. Sedimentary rocks are conducive to storing such signs but the age of such rocks is hard to determine. The Perseverance rover has now started drilling and collecting samples of the sedimentary rocks. These findings have been published in a paper in Science.
Years ago, a rock formation filled with the mineral olivine was spotted by Mars orbiters. The formation is spread over an area of 70,000 square kilometres. Scientists have come up with various theories to explain the formation including volcanic eruptions, and meteorite impacts, among others. In a new study, researchers have found that the olivine formed underground from slowly cooling magma after which it was exposed to erosion over time.
Perseverance scraped the surface of the rock exposing its composition and studied the patch. Researchers then used the rover's Planetary Instrument for X-ray Lithochemistry (PIXL) to determine the size of the olivine grains, which were found to be greater than expected. "This large crystal size and its uniform composition in a specific rock texture require a very slow-cooling environment. So, most likely, this magma in Jezero wasn't erupting on the surface,” said Yang Liu of NASA's Jet Propulsion Laboratory. He is the author of the second study published in Science.
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