Habitable Mars? The Mars rover has found its dream rock

If we think about it objectively, the ability to send a vehicle to another planet, capable of traveling tens of kilometers per day, analyzing terrain, weather, storing samples, and sending data back to Earth, is incredible. This is exactly what the spacecraft we send to Mars are doing. And now one of them, perseverance, He found a treasure.

If there is a Holy Grail on Mars, it will likely be a specific type of rock: a very important rock It contains convincing evidence of the habitability of ancient Mars. In fact, if you ask scientists what a sample would look like, the answer is easy: Which showed evidence of ancient water and was not the type that preserved ancient organic material.

Perseverance may have found it while exploring a geological region on the inner rim of Jezero Crater. The area is located in a narrow strip along the western rim of the crater. Orbital observations have shown that it is One of the richest carbonate areas on the planet.

“Its presence, along with the adjacent river delta, turned Jezero Crater into a crater The most attractive landing site for the mission “Perseverance Mars 2020”, Scientists noted At the 2024 Lunar and Planetary Science Conference.

The Perseverance team decided to take samples and store them with the rest of its core for eventual return to Earth. But first they scanned the rock surface using the rover's spectrometers. Then they scraped the surface of the rock and wiped it again. The results showed that the sample It is composed of 75% of cementitious carbonate granules each other using almost pure silica.

“Simply put, this is the type of rock we expected to find when we decided to investigate Jezero Crater,” says Ken Farley, a Perseverance project scientist at the California Institute of Technology in Pasadena, California. They form in water, and on land minerals are usually deposited in water Good for trapping and preserving ancient organic materials and bio-imprints. “The rock could also tell us about the climate conditions on Mars that existed when it formed.”

Here on our planet, carbonate minerals They can form directly around microbial cells. Once encapsulated, the cells can quickly become fossils and be preserved for a long time. This is what happened to some of the first evidence of life on our planet.

But there is something that makes this show even more interesting. They are microcrystalline rocks, meaning they are made of crystals so small that they can only be seen with microscopes. On Earth, crystalline rocks such as Precambrian chert exist Contains fossilized cyanobacteria. Could the same thing happen with this?

“The silica and parts of the carbonate appear to be fine crystals, which makes them very good at trapping and preserving signs of microbial life that may have lived in this environment before,” concludes Sandra Seljeström, a persistence scientist at the Swedish Research Institutes (RISE) in Stockholm. That's what makes this show excellent. For biosignature studies if he returns to Earth. Additionally, the sample could be one of the oldest cores yet collected by Perseverance, which is important because Mars was at its most habitable early in its history.