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

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

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

Scientists collaborating on the mission also say the rock samples the rover stored in tubes for a future return to Earth have the right chemical recipe for preserved 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 Journal reports are highly technical and devoid of hype – they dare to be dull as dirt – but the scientists involved make them a more exciting story.

“It’s amazing. We find organic matter in almost every rock,” said Abigail Allwood, a geologist at NASA’s Jet Propulsion Laboratory in Pasadena, which manages the rover and the broader Mars sample return mission.

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

“Crucially, the conditions in the rock during any migration of water through it could support small communities of microorganisms,” lead author Michael Tice, a geologist at Texas A&M University, said in an email. In a subsequent 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)

Persistence did a landing of bulls into the Jezero crater on February 18, 2021, and has been circling it ever since, storing rock samples along the way for later study back 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 will then carry these samples back to Earth for laboratory testing. The exact schedule is still to be determined, but NASA hopes to have the samples on home soil in the early 2030s.

This research on 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 despite the claims of UFO enthusiasts, the discovery of life beyond Earth remains ambitious.

Even finding organic matter—life-supporting molecules with combinations of carbon, hydrogen, and oxygen—is a long way from discovering life or even evidence of its presence in the past. Such molecules can be either biological or non-biological in origin.

Yet Mars is front and center in NASA’s search because it has many favorable features. Mars was probably much more Earth-like about 3 billion years ago, with warmer and wetter conditions. Life may once have existed on Earth and Mars at the same time, and it is possible that it originated on Mars and spread to Earth via meteorites. And although the surface is now an arid wasteland, the planet may have liquid water in significant quantities below the surface, and possibly a “mysterious” life.

Although the Perseverance rover does not have the instruments to chemically detect living organisms if they exist today, its instruments give scientists the ability to study the Martian surface at a level of detail never before possible.

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

Jezero Crater was formed by an impact – a rock crashing into Mars – at least 3.5 billion years ago. The shallow crater clearly had water a long time ago. This can be determined from orbital images showing the remains of a delta where a river flows into the lake. Planetary geologists had hypothesized that the crater floor was covered by sedimentary rock formed from dirt and debris that slowly accumulated on the lake floor.

If such sedimentary rock was ever there, it is gone now. It may have eroded, Theiss said. The lack of sedimentary rock could mean the lake didn’t last very long, which would be disappointing to astrobiologists. Life as we know it needs water and it takes time for more complex life forms to develop. If the lake didn’t hold back, life might struggle to take root.

The volcanic rocks are not a disappointment, however, because they store a lot of information about Mars’ past, including the presence of organic molecules, the scientists said. The presence of organic material on Mars has been confirmed in previous missions, but their exact nature and chemistry cannot be revealed by this kind of long-distance study and will require laboratory study on Earth, according to Bethany Ellman, a planetary scientist at Caltech and co-author of two of the new articles.

“Are they just organics washed into the system—perhaps from meteoric material that’s just part of the water?” That would be exciting to say the least. Or are they tiny niches of microbial life living in the cavities of these rocks? That would be the most exciting,” Elman said.

She added that the rover is “collecting a great array of samples to reveal the history of the Martian environment in all its forms — the volcanic history, the history of water, the relationship of organic matter to these water-rich environments.”

All of this is an attempt to solve the fundamental mystery of Mars: What went wrong? How and when and why did this apparently habitable planet become such a harsh place? The Red Planet may not be a dead planet — the coroner’s report is incomplete — but it sure looks 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—high-energy particles constantly streaming from the sun that can dislodge lighter molecules. Mars also lacks plate tectonics, the geological process that on Earth recycles the crust and continues to eject water and nutrient-rich lava through active volcanoes.

Somewhere along the way, Mars’ magnetic field died, and then it did became a different kind of planet. It lost almost all its atmosphere. It turned into a cold desert world. How quickly this happened is not known, but this is something that can be revealed from the volcanic rocks in the crater.

The magma contains some iron, which is sensitive to the planet’s magnetism. As the lava cools, it crystallizes into igneous rock, freezing electrons into the iron-bearing minerals in patterns that could reveal the characteristics of the 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: “In the end, we’re actually super lucky that there are igneous rocks in the crater and that we happened to land right on top of them, because they’re perfect to determine ages and study the past of Mars’ magnetic field.

Once the mission succeeds in sending its collection of gems back to Earth, scientists may finally be able to say whether life ever found a foothold on Mars – which would raise new questions about whether, despite the planet’s dramatic transformation, life on somehow managed to resist.

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