NASAThe Perseverance rover has collected rock samples tuesday This could revolutionize our understanding of the history of water on the planet and reveal past life.
The samples were collected over five months in 2022 from Jezero Crater as they were transported and deposited by water, possibly retaining evidence of past microbial life. However, detailed analysis needs to be done on Earth and future work will be required to retrieve them.
Over a roughly five-month period in 2022, NASA’s Perseverance rover will collect rock samples from Mars that could rewrite the Red Planet’s water history. They may even contain evidence of past life on Mars.
But the information they contain cannot be extracted without more detailed analysis on Earth, which would require a new mission to retrieve the samples and bring them back to the planet. Although NASA’s sample return mission may be delayed, scientists hope to have samples on Earth by 2033.
Importance of sedimentary rock samples
“These models are what made our work fly,” said paper co-author David Shuster, professor of Earth and planetary sciences. University of California, Berkeleyand a member of NASA’s Science Team for Sample Collection. “This is what everyone was hoping to achieve. We have accomplished that. These are the things we went in search of.
The critical importance of these rocks, taken from river deposits in a dry lake that once filled the crater Jezero, is described in a study to be published today (August 14). AGU AdvancesA Journal of the American Geophysical Union.
“These are the first and only sedimentary rocks that have been studied and collected from a planet other than Earth,” said David Schuster, a professor of Earth and planetary sciences at the University of California, Berkeley and a member of NASA. Scientific committee for sample collection. “Sedimentary rocks are important because they were transported by water, deposited in standing water, and then chemically modified, which at some point in the past included liquid water on the surface of Mars. The whole reason we came to Jezero was to study these types of rock types. These are absolutely fantastic samples for the main purposes of the mission. .”
The possibility of past life on Mars
Shuster co-authored the paper with first author Tanja Bozak, a geologist at the Massachusetts Institute of Technology.with) at Cambridge.
“These rock cores are the oldest materials sampled from any known environment that could have supported life,” Bozak said. “When we bring them back to Earth, they can tell us about when, why, and how long Mars had liquid water and whether some organic, prebiotic and possibly even biological evolution took place on the planet.”
Importance of fine-grained sediments
Notably, some of the samples contain very fine sediments, the type of rock that could retain evidence of past microbial life on Mars — if or when life ever existed on the planet.
“Liquid water is a key component in all of this because it’s the key ingredient for biological activity, as far as we understand it,” said geochemist Shuster. “Fine sedimentary rocks on Earth preserve signatures of past biological activity, including organic molecules. That’s why these samples are so important.
Recent findings from Cheyava Falls
On July 25, NASA announced that Perseverance collected new rock samples from the Cheyawa Falls, named after Mars, that may contain signs of past life on Mars. The rover’s science instruments found evidence of organic molecules, while “spotted” inclusions in rocks resemble features often associated with fossilized microbial life on Earth.
In a statement, Caltech’s Persistence Project Scientist Ken Farley said, “Scientifically, persistence has nothing more to offer. To understand what really happened billions of years ago in the Martian river valley in Jezero Crater, we want to bring the Cheyava Falls sample back to Earth so it can be studied with the powerful tools available in laboratories.
Unanswered questions about organic compounds
A fan of Jezero and the river sediments that once flowed into it, Shuster noted, may have formed 3.5 billion years ago. That abundant water is now gone, either trapped underground or lost to space. But Mars was wet at a time when life on Earth — in the form of microbes — was already everywhere.
“3.5 billion years ago, life was doing its thing on Earth at that time,” he said. “The fundamental question is: Did life also do its job on Mars at that time?”
“Anywhere on Earth in the last 3.5 billion years, if you give me a situation where a river flows into a trough, carrying material to an aquifer, biology will have left its mark in one way or another,” Shuster said. We’ll have a good chance of recording that biology in the laboratory observations we can make on it.”
Shuster and Bossak agree that organic analysis instruments on the rover did not detect organic molecules in four samples from the sediment fan. Organic molecules are used and produced by organisms we are familiar with on Earth, although their existence is not a clear proof of life.
“We clearly did not observe organic compounds in these core samples,” Shuster said. “But just because the instrument didn’t detect organic compounds doesn’t mean they aren’t present in these samples. It just means they aren’t present in certain rocks at concentrations detectable by the rover instrument.”
Sample Collection Milestones of Persistence
To date, Perseverance has collected a total of 25 samples, including duplicate and atmospheric samples, as well as three “witness tubes” that capture potential contaminants around the rover. Eight duplicate rock samples and an atmospheric sample and witness tube were placed on Jezero’s surface in what is known as the Three Forks Cache as a backup in case the rover runs into trouble and cannot retrieve internal samples. Another 15 samples, including the Cheyawa Falls sample collected on July 21, are on the rover for recovery.
Analyzing Ancient River Deposits on Mars
Shuster was part of a team that analyzed the first eight rock samples collected, two from each site on the crater floor, all of which were volcanic rocks formed when a meteorite impact hit the surface and dug the crater. Those results, reported in a 2023 paper, were based on analyzes of tools in due diligence.
The new paper is an analysis of seven more samples, three of which are now temporarily stored on the Martian surface, collected between July 7 and November 29 2022 from the front of the western sedimentary fan at Jezero. Bozak, Shuster and their colleagues found that the rocks are mostly composed of sandstone and mudstone, all formed by fluvial processes.
Unlocking Mars’ Water History
“Diligence encountered hydrous sedimentary rocks along the front, top, and margins of the West Jesero fan and collected a sample suite consisting of eight carbonate-bearing sandstones, sulfate-rich mudstone, sulfate-rich sandstone, and sand-pebble conglomerates,” Bozak said. are much older, whereas the rocks collected above the fan may be younger rocks produced during water activity and sediment deposition on the western fan.”
While Bozak is most interested in possible biosignatures in the finer sediments, the coarser-grained sediments also contain important information about water on Mars, Shuster said. Although there is little chance of preserving organic matter or potentially biological material, they include carbonate material and detritus washed upstream by the now extinct river. They could help determine when water actually flows on Mars, a major thrust of Shuster’s own research.
“Through laboratory analysis of those detrital minerals, we can make quantitative statements about when the sediments were deposited and the chemistry of that water. What was the pH (acidity) of that water when those secondary phases fell? At what time did that chemical change occur?” “We now have a mix of these samples in the sample set that will help us understand the environmental conditions when liquid water flows into the crater,” he said. When did that liquid water flow into the crater? Is it in between?”
Future work and laboratory analysis
Answers to these questions rely on analyzes of materials returned to terrestrial laboratories to discover the organic, isotopic, chemical, morphological, geological and paleomagnetic information they record, the researchers emphasize.
“One of the most important planetary science goals is to bring these samples back,” Shuster said.
Reference: “Astronomic potential of rocks recovered by the Perseverance rover at the face of a sedimentary fan in Jezero Crater on Mars” 14 Aug 2024, AGU Advances.
