Organic molecules in rocks on Mars, “a possible signature of life”. The Perseverance rover, sent by NASA to the red planet, has collected rock samples in an area considered particularly significant by scientists, as the American space agency announced from its site. In the rocks, according to NASA, there are organic molecules potentially attributable “to a substance or a structure that could constitute proof of the existence of a past life” on Mars “but which could also have been produced without there being life”.
The rover has collected 4 samples from the area corresponding to an ancient river delta in the Jezero crater since 7 July: the total of rock samples considered scientifically relevant has risen overall to 12.
“We chose to send Perseverance to explore Jezero crater because we thought it had the best chance of providing scientifically excellent samples. We now know we have sent the rover to the right location,” said Thomas Zurbuchen, NASA’s chief scientist, speaking from Washington.
The Jezero crater, about 45 km wide, in the past hosted a delta – believed to be produced by the convergence of a river and a lake about 3m5 billion years ago – and currently collects sedimentary rocks. In the first exploration, Perseverance had explored the bottom of the crater by identifying igneous rock, produced by magma in the subsoil or by volcanic activity on the surface.
As NASA recalls, organic molecules can comprise a wide variety of compounds consisting mainly of carbon. They usually include hydrogen and oxygen atoms but may also contain other elements such as nitrogen, phosphorus and sulfur. The formation of these molecules is linked to chemical processes that ‘do not require life’, but “some of these compounds are – as NASA points out – ‘the chemical building blocks of life’.
The spotlight is particularly on ‘Wildcat Ridge’, as a rock about 1 meter wide was named that probably formed billions of years ago when mud and fine sand settled in an evaporating saltwater lake. On July 20, the rover collected material from the Wildcat Ridge surface to conduct analyzes with the instrument called Scanning Habitable Environments with Raman & Luminescence for Organics & Chemicals (SHERLOC).
The tests showed that organic molecules correlated with those of sulphates are present in the samples: the minerals found in the sedimentary rock layers can provide significant information on the aqueous environments in which they formed.
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