For one thing, the location Perseverance is currently exploring is the bottom of a former river delta, flowing into a lake that is now Jezero Crater. On the other hand, finding organic material in two rock samples out of the four analyzed shows that the robot is on a good vein. These rocks are a few billion years old, at a time when, it is believed, Mars was much more hospitable.
“These are two of the most important samples we will collect on this mission,” said at a press conference David L. Schuster of the University of California, one of the geology experts on the Perseverance team.
He and other experts however, were careful to point out that organic molecules is not synonymous with life. Purely chemical processes may explain their presence in these rocks. But this is precisely the type of “signature” What do biologists look for?.
The equipment on board Perseverance does not allow us to go further and provide definitive proof. For that, it will be necessary to wait until these rocks have been repatriated to Earth – since Perseverance is only the first phase of a long mission. He must collect a sufficient number of samples deemed interesting (12 so far), leaving some behind him in metal tubes that, in the next decade, a new probe (Mars Sample Return) will come to pick up and bring back to Earth. This one, a collaboration of the European and American space agencies, should in theory leave in 2028.
Arriving on the red planet in February 2021, Perseverance -in the company of its “helicopter” Ingenuity- spent its first year exploring the “bottom” of the crater, before heading towards what planetary scientists considered to be its real purposef: the bed of a dry delta. The probe had also landed further than expected from this delta, which explains the time it took to reach it: it finally arrived there last April. Logically, the flow of a river should have left in its delta a greater number of sedimentary rocks and debris from several places upstream.
One of the two rocks is what geologists call a sandstone, which is the result of the aggregation of mostly sandy grains. The other rock is a mudstone a sedimentary rock originally composed of mud or clay. If, as is supposed, it formed while the lake was evaporating, it might have kept traces of microbial life, assuming such a thing existed 3 billion years ago.
Signs of organic material had previously been found in the crater, but in much less encouraging quantities than here. “Signals were present at almost every point in every scan,” added the instrument expert who performed this analysis (Scanning Habitable Environments with Raman & Luminescence for Organics & Chemicals), Sunanda Sharma.
