NASA’s Mars Perseverance rover unearths clues in hunt for life


At the bottom of a shallow crater on Mars, the NASA’s Perseverance rover hit what scientists hope is paying the dirt. The Martian rocks excavated by the rover show signs of an aquatic past and are loaded with the kind of organic molecules that underlie life as we know it.

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

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

“It’s amazing. In almost every rock we find organic material,” said Abigail Allwood, a geologist at NASA’s Jet Propulsion Laboratory in Pasadena, which operates the rover and the larger Mars Sample Return mission.

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

“Crucially, the conditions in the rock whenever water migrated through it could have supported small communities of microorganisms,” said lead author Michael Tice, a geologist at Texas A&M University, 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 landing in the bullseye in Jezero Crater on February 18, 2021, and has been roaming it ever since, caching rock samples along the way for later examination on Earth. It’s 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 ability to launch samples into orbit. A spacecraft would then bring these samples back to Earth for laboratory research. The precise timeline is yet to be determined, but NASA hopes to have the samples on its own ground by the early 2030s.

This study of Mars is part of the efflorescence of the young 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 the claims of UFO enthusiasts notwithstanding, the discovery of life beyond Earth remains an aspiration.

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

Yet Mars is the focus of NASA research because it exhibits many favorable traits. Mars was probably much more like Earth around 3 billion years ago, with warmer and more humid conditions. Life may have 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 a barren wasteland, the planet could have liquid water in significant amounts below the surface, and perhaps a “cryptic” life.

Although the Perseverance rover lacks the 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 possible.

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

Jezero Crater formed during an impact event – rock slamming on Mars – at least 3.5 billion years ago. The shallow crater clearly contained 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 bottom of the crater was covered with sedimentary rock, formed of soil and debris that was slowly accumulating at the bottom of the lake.

If such a sedimentary rock ever existed, it is gone now. It may have eroded, 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.

The volcanic rocks aren’t a disappointment, however, as they retain a lot of information about the Martian past, including the presence of organic molecules, the scientists said. The presence of organic matter on Mars had been confirmed on previous missions, but their precise nature and chemistry cannot be discerned by this type of long-range research and will require careful lab examination on Earth, according to planetary scientist Bethany Ehlmann. at Caltech and co-author of two of the new papers.

“Are they just organic material that kind of washed into the system – maybe from meteoritic material that was just part of the water? That would be the least exciting. Or is it- There are little niches of microbial life living in the cavities of these rocks? That would be the most exciting,” Ehlmann said.

She added that the rover “collects an impressive set of samples to reveal the environmental history of Mars in all its forms – the volcanic history, the water history, the relationship between organic matter and these rich environments. in water”.

This is all an attempt to solve the fundamental mystery of Mars: what went wrong? How, when and why did this seemingly life-sustaining planet turn into such a hostile place? The red planet may not be a dead planet – the coroner’s report is incomplete – but it certainly looks like one.

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

Somewhere along the way, Mars’ magnetic field died out, and then it has become a different type of planet. It has lost almost all of its atmosphere. It has become an icy desert world. How quickly this happened is unknown, 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 the lava cools, it crystallizes into igneous rock, freezing the electrons in the iron-bearing minerals into patterns that could reveal characteristics of a magnetic field, such as its orientation.

Benjamin Weiss, planetary scientist at MIT and co-author of two of the papers, said in an email: “Overall, we’re actually very lucky that there are igneous rocks in the crater, and that we landed right on it. , as they are ideal for determining ages and studying the past history of the magnetic field of Mars.

Once the mission can return its precious collection of rocks to Earth, scientists will finally be able to tell if life has ever found a foothold on Mars – raising new questions about whether, despite the planet’s dramatic transformation, life managed to persevere. .

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