This is the most exciting rock ever discovered on Mars
Mysterious “leopard spots” on a Martian rock may also simply be evidence of extraterrestrial life or undeniable lifeless chemistry. Discovering the fact would possibly require bringing the rock back to Earth.
By Lee Billings
NASA’s Perseverance Mars rover took this selfie, consisting of 62 individual images, on July 23, 2024. A rock nicknamed “Cheyava Falls,” which has tantalizing features that suggest it could possibly contain ancient microbial fossils, lies below. the left of the rover, close to the center of the image.
NASA/JPL-Caltech/MSSS
In a dry river valley on Mars, NASA’s Perseverance rover may have finally discovered its raison d’être: evidence of ancient extraterrestrial life and, with it, a lifeline for the space agency’s ambitious but troubled mission to bring materials back from the planet. Red Planet to Earth.
This possible evidence of a cosmic earthquake would possibly seem like an undeniable rock, but it’s unlike any previous discovery on Mars. The rock, nicknamed “Cheyava Falls” after a feature in Earth’s Grand Canyon, appears to be a coffee table-long outcrop of shale, shaped like an arrowhead. But its most notable visual feature is its reddish and whitish stripes: the former are dotted with light-colored spots rotated by dark ones reminiscent of a leopard’s spots. The maximum red color likely comes from hematite, an iron mineral, according to the Perseverance team. The rover’s studies revealed that the whitish streaks were veins of calcium sulfate deposited in the water, and show that the dark edges of the curious “leopard spots” involve iron phosphate molecules, a potential food for hungry underground microbes.
Perseverance’s tools also show that the rock comprises biological compounds, carbon-based molecules that make up the building blocks of life as we know it. It’s a rare location for the rover, which has been exploring in and around the planet’s Jezero Crater since its landing in February 2021. (Perseverance’s precursor, the Curiosity rover, also discovered biological curtains in its explorations of another region, Gale Crater. )
If you like this article, support our award-winning journalism by subscribing. By purchasing a subscription, you help protect the future from difficult stories about the discoveries and concepts that shape our world today.
Taken together, the Perseverance data not only shows that water seeped through Cheyava Falls long ago, but also that the shale was once home to other situations related to microbial life. In sedimentary rocks containing hematite on Earth, chemical reactions can create similar pale and ringed hues. stains, and those reactions release energy that can keep single-celled organisms inside the stone.
This was more than enough to force the Perseverance team to order the rover to drill and hide some of the rock in one of its pattern tubes for possible recovery and delivery to Earth through long-duration missions. This take-home plan, called Mars Sample Return (MSR), is a collaboration between NASA and the European Space Agency (ESA). It is controlled through NASA’s Jet Propulsion Laboratory (JPL), which also built and operates Perseverance. However, significant delays in the schedule and multimillion-dollar budget cost overruns have left the task in uncertainty. MSR is being replanned lately to find a faster and less expensive way to bring Perseverance’s valuable pattern caches back to Earth.
“Cheyava Falls is the most puzzling, complex, and potentially vital rock ever studied by Perseverance,” Ken Farley, Perseverance project scientist at the California Institute of Technology, said in a July 25 NASA statement announcing the discovery. “On the one hand, we have our first convincing detection of biological matter, uniquely colored blobs that indicate chemical reactions that microbial life can also use as an energy source, and transparent evidence that water, necessary for life, once passed through rock. On the other hand, we have not been able to determine precisely how the rock formed and to what extent neighboring rocks would have possibly heated the Cheyava Falls and contributed to those characteristics.
The Perseverance team detected and targeted the rock in late June as the rover traversed the northern slope of Neretva Vallis, a half-kilometer-wide channel dug eons ago through a river that flows into Jezero Crater, which was once home to a giant lake and delta system. As Perseverance’s first observations of the rock slowly returned to Earth in the form of radio waves, the increasingly amazed team began a frantic 24-hour race to gather as much knowledge as imaginable — and a very important pattern — before the rover has to move. in other previously planned objectives.
Captured by the Perseverance rover on July 18, 2024, this close-up symbol of the Martian rock “Cheyava Falls” displays several intriguing features. Bands of iron-rich reddish material, filled with “leopard spot” mineral deposits, grow larger between white veins of calcium sulfate studded with green olivine crystals. Scientists have yet to fully decipher this aggregate of minerals, which may simply be evidence of the lifestyle of ancient Martian microbes.
NASA/JPL-Caltech/MSSS
Cheyava Falls likely would have formed first from dust cemented into the river bed, and the striking veins of calcium sulfate were later deposited through mineral-rich fluids seeping through cracks in the rock. . But this undeniable situation is confused by anything else that Perseverance has detected in the veins of the rock: small crystals of olivine, a greenish mineral that is extracted from magma. According to rover scientists, the presence of the mineral in the veins may also simply mean that the olivine and sulfate were transported to the rock through inhospitable hot water. currents and that leopard spots were formed by completely abiotic chemical reactions at maximum temperatures.
“The rocks above and north of Cheyava Falls, known as the ‘marginal unit,’ are very distinct and enriched in olivine,” says Katie Stack Morgan, associate scientist for the Perseverance mission at JPL. “The olivine we see in the Cheyava Falls veins would possibly be similar to the site of the nearby olivine-rich marginal unit. “
Previous observations through Perseverance have revealed that the composition of the exposed bedrock downstream of Cheyava Falls is very similar, even adding biological matter and small dark clusters of minerals, Stack Morgan says. But no other rock tested so far shows the leopard’s unique spots.
Despite those hard-to-understand origins, the Cheyava Falls sites unmistakably resemble structures that, when discovered in rocks deep within the Earth, are sometimes considered symptoms of life: so-called biosignatures. Technically called “reduction spheroids,” those features are commonly formed from biological matter buried in sedimentary rocks rich in oxidized or oxidized iron, which gives the rock a reddish color. Flowing water can facilitate “redox” reactions between biological matter and surrounding rock, cutting (donating electrons) the oxidized iron and discoloring it. Microbes in the rock can rely on this process, employing the flow of nutritious electrons to fuel their metabolism. The end result is a pale sphere of reduced iron combined with other indirect metals and, potentially, microbial microfossils, a kind of oasis buried deep underground.
“It’s significant that those [reduction spheroids] are probably the only biosignatures of underground microbial life that you can see with your eyes or with our rover’s cameras,” says David Flannery, an astrobiologist and member of the Perseverance science team at the University of Queensland. in Australia. But since such structures can also be the result of purely abiotic processes, they cannot alone constitute irrefutable evidence of life beyond, especially when studied remotely via a robot on an alien planet millions and millions of years away. kilometers away. Even on Earth, Flannery says, “there are strangely small paintings on [reduction spheroids], partly because it’s very difficult to discover those things. “
Although the Cheyava Falls are far from evidence of life on Mars, for scientists who can’t examine them in more detail, it’s the next most productive element: the most promising rock ever seen to potentially find fossilized Martians.
“It’s exciting,” says Caleb Scharf, a senior astrobiology scientist at NASA Ames Research Center, who is not part of the Perseverance team. “The discovery of Cheyava Falls represents one of the most productive arguments in favor of returning samples from Mars or sending them new devices and tools that expand the way we can interrogate evidence on Mars. “
“We destroyed this rock with lasers and X-rays and photographed it literally day and night from almost every angle imaginable,” Farley said in a recent NASA statement. “Scientifically, Perseverance has nothing more to contribute. To fully perceive what happened in this Martian river valley in Jezero Crater billions of years ago, we’d like to bring the Cheyava Falls pattern back to Earth, so it can be studied with the powerful tools available in laboratories.
According to Stack Morgan, those rugged tools would come with giant, sensitive electron microscopes and mass spectrometers, which are not suitable for an interplanetary robot. Such a device can simply read about the pattern of a wide diversity of biosignatures while identifying main points such as the age of the dark edges of leopard spots, the timing of the rock’s interactions with water and even the temperature at which some of its minerals were formed. Perhaps most importantly, although Perseverance is currently silent on the nature of the biological compounds in the Cheyava Falls, devices on Earth can reveal the type and complexity of the molecules contained in this curtain and whether it has biological origins.
However, NASA and ESA will first have to figure out how MSR can bring it home.
Lee Billings is a science journalist specializing in astronomy, physics, planetary science, and spaceflight, and editor of Scientific American. He is the author of the critically acclaimed book, Five Billion Years of Solitude: The Search for Life Among the Stars, which won a science communication award in 2014 from the American Institute of Physics. In addition to his work for Scientific American, Billings’ writings have appeared in The New York Times, The Wall Street Journal, The Boston Globe, Wired, New Scientist, Popular Science, and many other publications. Billings, a dynamic speaker, has been a guest lecturer for NASA’s Jet Propulsion Laboratory and for Google, and has served as M. C. for occasions organized through National Geographic, the Breakthrough Prize Foundation, Pioneer Works, and other organizations. Billings joined Scientific American in 2014 and previously worked as an editor at SEED magazine. He holds a B. A. in journalism from the University of Minnesota.
Learn about and share the most interesting discoveries, innovations and concepts that are shaping our world today.
Follow:
Scientific American is part of Springer Nature, which owns or has business relationships with thousands of clinical publications (many of which can be found in www. springernature. com/us). Scientific American maintains a strict policy of editorial independence when communicating clinical advances. to our readers.
© 2024 SCIENTIFIC AMERICAN, A DIVISION OF SPRINGER NATURE AMERICA, INC. ALL RIGHTS RESERVED.