NASA’s Mars Perseverance rover finds clues in the hunt for life


On the floor of a shallow crater on Mars, NASA’s Perseverance rover struck what scientists hope is a fatal blow. The Martian rocks excavated by the rover show signs of a watery past and are laden with the kind of organic molecules that underpin life as we know it.

Scientists collaborating on the mission also say that the rock samples, which the rover has hidden in tubes for a future return to Earth, have the right chemical recipe for preserve evidence of ancient Martian life, if it ever existed.

Perseverance’s new research is detailed in three large studies published Wednesday, one in the journal Science and two in the journal Science Advances. The the journal reports are highly technical and hype-free – daring to be boring as dirt – but the scientists involved translate them into a more exciting narrative.

“It’s amazing. In almost all rocks we find organic substances,” said Abigail Allwood, a geologist at NASA’s Jet Propulsion Laboratory in Pasadena, who manages the rover and the larger Mars Sample Return mission.

One of the studies concluded that the rocks in the crater experienced three different events where they were exposed to water.

“Basically, the conditions in the rock during each time water migrated through it could have supported small communities of microorganisms,” lead author Michael Tice, a geologist at Texas A&M University, said in an email. In a later interview, he added, “We won’t know until we get the samples back to Earth.”

On February 18, 2021, NASA successfully landed the Perseverance rover on Mars. Here is a live video of the landing. (Video: NASA, Photo: NASA/NASA)

Perseverance made a target landing in Jezero crater on February 15th. 18, 2021, and has roamed it ever since, caching rock samples along the way for later inspection on Earth. This is an ambitious, multi-phase mission that will require NASA and its partner, the European Space Agency, to send another vehicle to the surface of Mars with the capability to launch samples into orbit. A spacecraft would then bring those samples back to Earth for laboratory research. The precise timetable has yet to be determined, but NASA hopes to have the samples in house in the early 2030s.

This study of Mars is part of the burgeoning field of astrobiology, which includes the search for potentially habitable worlds and the first example of extraterrestrial life. Despite the efforts of generations of scientists and despite the claims of UFO enthusiasts, the discovery of life beyond Earth remains an ambition.

Even finding organic substances — life-friendly molecules with combinations of carbon, hydrogen and oxygen — is a far cry from discovering life or even proving its presence in the past. These molecules can be of biological or non-biological origin.

However, Mars is the focus of NASA research because it has many auspicious traits. Mars was probably much more like Earth about 3 billion years ago, with warmer and wetter conditions. Life may have once existed on Earth and Mars simultaneously, and it is possible that it originated on Mars and spread to Earth via meteorites. And although the surface is now arid desert, the planet may have liquid water in significant quantities beneath the surface, and possibly “cryptic” life.

While the Perseverance rover lacks instruments to chemically detect living organisms, if they exist today, its instruments give scientists the ability to study the Martian surface in a level of detail never before achieved.

One of the new papers taking a closer look at the chemistry of Mars has surprised geologists. They had thought they were going to dig up a pile of sedimentary rocks. Instead the rocks are volcanic.

Jezero crater was formed in an impact event – a rock slamming into Mars – at least 3.5 billion years ago. The shallow crater clearly held water a long time ago. This could be determined from orbital images showing the remains of a delta where a river flowed into the lake. Planetary geologists had assumed that the floor of the crater was covered in sedimentary rock, formed by dirt and debris that slowly accumulated on the bottom of the lake.

If such sedimentary rock ever existed, it’s gone now. It may have eroded away, Tice said. The lack of sedimentary rock could mean the lake didn’t last very long, which would be disappointing for astrobiologists. Life as we know it needs water and it takes time for more complex life forms to evolve. If the lake hadn’t lingered, life might have struggled to take root.

Volcanic rocks aren’t a disappointment, though, because they hold a lot of information about the Martian past, including the presence of organic molecules, the scientists said. The presence of organic material on Mars had been confirmed in previous missions, but their precise nature and chemistry cannot be pinpointed through this type of long-distance search and will require laboratory examination on Earth, according to Bethany Ehlmann, a planetary scientist at Mars. Caltech and coauthored two of the new papers.

“Are they simply organic matter that came into the system, perhaps from meteorite material that was just a part of water? That would be the least exciting. Or are they small niches of microbial life living in the hollows of these rocks? That would be the most exciting thing” Ehlmann said.

He added that the rover “is collecting an impressive array of samples to reveal the environmental history of Mars in all its forms: the volcanic history, the history of water, the relationship between organic matter and those water-rich environments.”

All of this is an attempt to solve the fundamental mystery of Mars: what went wrong? How, when and why did this seemingly life-friendly planet turn into such a harsh place? The Red Planet may not be a dead planet — the coroner’s report is incomplete — but it sure does look like one.

Scientists point to something Mars lacks today: a global magnetic field like Earth’s. Such a field protects our atmosphere from the corrosive effects of the solar wind – constantly flowing high-energy particles from the sun that can strip away lighter molecules. Mars also lacks plate tectonics, the geological process that recycles Earth’s crust and continues to spew water and nutrient-rich lava through active volcanoes.

Somewhere along the way, Mars’ magnetic field died, and then it has become a different kind of planet. It loses almost all of its atmosphere. It has become a freezing desert world. It is not known how quickly it happened, but it is something that could be revealed by the volcanic rocks in the crater.

Magma contains a certain amount of iron, which is sensitive to a planet’s magnetism. As lava cools, it crystallizes into igneous rock, freezing electrons within iron-bearing minerals in patterns that could reveal traits of a magnetic field, such as its orientation.

Benjamin Weiss, a planetary scientist at MIT and co-author of two of the papers, said in an email: “On balance, we are very lucky indeed that there are igneous rocks in the crater and that we happened to land right on them. , as they are ideal for determining ages and studying the past history of Mars’ magnetic field.

Once the mission can send its precious collection of rocks to Earth, scientists may finally be able to tell whether life has ever found a foothold on Mars, which would raise new questions as to whether, despite the dramatic transformation of the planet, life has somehow managed to persevere. .

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