Mars Rover offers new clues to the possibility of ancient life

IIt is one of our great cosmic misfortunes that we missed the Golden Age of Mars entirely. About 3.5 billion years ago, during the first billion years of the solar system’s existence, the red planet was a blue planet, flooded with oceans, seas and rivers like Earth. is today. Ancient sedimentary basins, deltas and riverbeds are all that remains of Mars’ aquatic past, which ended when the planet’s magnetic field shut down, allowing the solar wind to rip the atmosphere and water from spitting into space.

But a lot could have happened in that first billion years, including the emergence of life. On Earth, life began long before the planet’s billionth birthday, leading many exobiologists – scientists who study the possibility of extraterrestrial life – to believe that anywhere there is liquid water and the proper chemistry , biology can quickly impose itself.

“Life on Earth started very quickly,” astronomer Seth Shostak of SETI (Search for Extraterrestrial Intelligence Institute) once told me. “It’s like walking into a casino in Las Vegas, pulling the handle and hitting the jackpot. You say, “Well, either I’m very lucky or it’s not a tough bet.”

The Perseverance rover first landed on Mars in February 2021. And this week, as NASA reports, the rover gathered new evidence that that gamble may have paid off on Mars, too. In late July, Perseverance abraded some samples of a formation in Mars’ Jezero crater that astronomers have dubbed Wildcat Ridge – a sedimentary rock about 3 feet wide that formed more than three billion years ago. years when the saltwater lake that once filled the crater began to evaporate and fine sand and mud began to settle.

By studying the samples with an onboard instrument called SHERLOC—Scanning Habitable Environments with Raman & Luminescence for Organics & Chemicals—Perseverance has now found organic chemistry in the ancient mud, including the presence of carbon, hydrogen, and nitrogen; further analysis may also reveal nitrogen, phosphorus, and sulfur. All of these ingredients are present in biologically rich environments on Earth.

“In the distant past, the sand, mud and salts that now make up the Wildcat Ridge sample were deposited under conditions where life could potentially have thrived,” Caltech Perseverance Project Scientist Ken Farley told Reuters. Pasadena, Calif., in a statement. “The fact that organic matter was found in such sedimentary rock – known to preserve fossils of ancient life here on Earth – is significant.”

That’s the good news. The not so good news – or at least the least immediate gratifying – is that it will still be a long time before scientists can know if the ingredients of Martian biology actually mean the distant (or even extant) past. presence of Martian biology. Perseverance’s suite of instruments is limited in what they can study, and in order to search for evidence as strong as ancient microfossils, the samples the rover collects must be studied closely by scientists in a lab.

For this reason, the rover is equipped with 43 titanium sample tubes in which it caches the Martian soil and rock it studies. So far, a dozen tubes have been filled and sealed, and all will eventually be deposited in a well-marked spot on the Martian surface. As early as 2028, NASA and the European Space Agency (ESA) will launch a sample return mission to Mars, in which a lander will collect the tubes, blast them off the surface of Mars, and transfer them to an orbiter that will bring them back. at their home.

NASA’s long-term goal, of course, is to have humans on Mars who can do this kind of work more easily and on the site. But the key here is the “long term” factor. Don’t look for Mars boot footprints until the mid-2030s or even later. In the meantime, the sample-return scenario is our best bet on whether our once-watery planetary neighbor was also a once-living neighbor. The discovery just announced by Perseverance raises the possibility – at least a little – that the answer to this question is yes.

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Write to Jeffrey Kluger at [email protected]

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Write to Jeffrey Kluger at [email protected]

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