NASA finds ‘bricks of life’ in rocks in lake delta on Mars

NASA presented this Thursday (15) a performance report on the mission of the Perseverance rover in the Jezero crater, on Mars, and the scientists’ enthusiasm seemed palpable with the confirmation that there is an appreciable amount of organic molecules, the basic building blocks for the life, in the harvested material — even though “delayed gratification” is the real name of the game.

This is because the robotic vehicle can conduct the analysis of the rocks it has been harvesting in a limited way, dictated by the capacity of its instruments. The result is insufficient to answer the big questions surrounding the mission, such as the search for evidence of life in the past on Mars. But that is likely to change when the material is brought to Earth for in-depth study — which should not happen until 2033.

“The reality is that the level of evidence for establishing life on another planet is very high. And it seems unlikely to most of us that the evidence is so convincing. [em observações com o rover] that we can do that,” says Ken Farley, a project scientist at Perseverance and a researcher at Caltech, the California Institute of Technology. [com o rover]. The most we can probably do is a potential detection.”

The situation, of course, changes when you think that many of these rocks will be brought back to Earth for further analysis. Then, just the fact that the scientists were able to confirm that the choice of Jezero Crater for the rover expedition was correct and what they expected to find is actually there is enough to cheer up.

“It’s fair to say that these are already the most valuable rock samples ever collected in history,” said David Shuster, a sample scientist at Perseverance and a researcher at the University of California at Berkeley.

“The samples we collected have the ingredients for life, in terms of the environmental context. This material was transported by water, it was deposited in a lake, we have fine particles that were settling in the lake, we have phases that were formed during the evaporation of the lake, all these things, as we discussed, have high potential for preserving biosignatures. If these conditions have existed anywhere on Earth at any point in time in the last, say, 3.5 billion years, I think it’s safe to say, or at least assume, that biology would have done its thing and left its mark on these rocks for us to observe. So that’s why we’re so excited to be able to answer these questions by bringing these samples into labs here on Earth. “

FROM IGNEOUS TO SEDIMENTARY ROCKS

For the sake of flight safety, the rover landed deeper into Jezero Crater, where the terrain was less rugged, in February last year. When analyzing these rocks closer to the landing site, there was some surprise to find that they were igneous — that is, formed by lava that flowed into the crater in its most remote past.

The find showed that the crater, formed about 3.8 billion years ago, has a more complex history than previously thought. It is known that there was a persistent lake of salt water in its interior for some time, and the dry delta that exists to the west of it (primary target of the mission) as well as traces on the edges demonstrate this clearly – clear signs of water flowing inwards. of the crater and depositing itself in large quantities inside.

Some samples of igneous rocks were collected by the mission and, although they do not offer the greatest potential in the search for so-called biosignatures (the detection of molecules that were associated with life in the past), they allow us to date precisely when the lava flow that formed them occurred. The delta, in turn, was generated later, signaling that the lake came after the lava flow at the bottom of the crater. “Whether there were other instances of the lake before this flow, we have no way of knowing,” says Farley. “What we can see is the last iteration of it, which was the one that produced the delta.”

In an unprecedented run by a robotic vehicle on the surface of another planet, Perseverance covered 5 km in 31 days between March and April until it reached the delta. It is in that region that he has been working since then, and it is from there that the most interesting samples for the search for life come, composed of sedimentary rocks, that is, deposited in layers by the running water advancing towards the interior of the crater.

“We’ve seen signals of organic material on every target we’ve analyzed since we landed, here and there, but they’ve gotten more intense as we’ve moved into the delta region, to the point where we see it at every analysis point on every measurement,” Sunanda said. Sharma, a scientist at JPL (Nasa’s Jet Propulsion Laboratory) linked to the rover’s Sherloc instrument, which is capable of determining the chemical composition of rocks on a relatively small scale, with multiple measurement points in an area the size of a eraser tip on a pencil.

“To put it simply, if this were a scavenger hunt for potential signs of life on another planet, organic matter is a clue, and we’re picking up stronger and stronger clues as we move forward in our delta campaign.”

Over the next year, the rover will continue to advance through the delta and aim to reach the edge of the dry lake. At the beginning of this journey, it can still make its first deposition of sample tubes on the ground for future collection by the missions that should promote its sending to Earth, in a partnership between NASA and ESA, space agencies in the US and Europe.