Potential Biosignatures on the Red Planet
The Perseverance rover discovered these biosignatures in a sedimentary rock called Wildcat Ridge that is about three feet tall and located in a river delta in Jezero Crater, the meeting place of an ancient lake and a river that once flowed there 3.5 billion years ago. .
It should be understood that these biosignatures do not represent proof of the presence of life on Mars, since they can be created by biological processes as well as by other mechanisms that do not involve such a phenomenon. However, these biosignatures indicate that there is a possibility of detecting ancient microbial life on Mars. Therefore, before stating that the compounds found come from a form of life, it is imperative to take into account the other processes that may have produced these molecules.
What is a biosignature? A biosignature, sometimes called a bioindex, is a chemical trace that has been preserved in the soil and that was formed at some point in the history of the place by a process involving some form of life. This chemical fingerprint is very often an organic molecule, as is the case with the planet Mars.
Biosignatures are invaluable allies for scientists, since they allow us to identify the chemical processes used by living beings, such as the bacteria that produced them.
Biosignatures can also be found in the atmosphere in the form of accumulated gas. It should also be clarified that the study of biosignatures is based on carbon-based life as we know it on Earth.
(Also read: Mars: what does this amazing photo taken by Perseverance represent?)
It will be confirmed when the samples return to Earth in 2033!
These organic molecules were detected in rock cores taken from Wildcat Ridge rock by the rover and stored in sealed, finger-sized tubes. Perseverance also took other samples, including one from the Martian atmosphere.
The biological signatures were detected by the SHERLOC (Scanning Habitable Environments with Raman and Luminescence for Organic and Chemical Compounds) instrument which revealed carbon-containing organic molecules at the very heart of weathered rocks, but also in rock dust.
The preservation of organic molecules within the rocks in Jezero Crater means they could be actual biosignatures of, say, a bacterial life form that existed at some point in the Red Planet’s history.
However, in order to confirm this, we will have to wait for the samples to return to Earth for laboratory analysis, but this can take a long time! In 2028, a machine carrying a lander equipped with a miniature rocket will take off in the direction of Mars and will be placed in orbit around the red planet. The lander and rocket will land on the planet’s surface not far from the Perseverance roller. The collected samples will be placed on the mini-rocket using a robotic arm that will take off to join the return spacecraft. The path to Earth will be long, but the samples should land safely in the Utah desert in the United States in 2033!
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Jezero Crater and its fascinating history with water
Video of Jezero Crater explored by Perseverance. Source: NASAJPL/YouTube
It is a safe bet that, upon their return to Earth, these samples, including rock samples with biosignatures, but also other samples already taken and future ones, will be awaited as the Holy Grail by scientists.
If NASA chose the Jezero crater, it is not by chance. The rock sampled by the Perseverance rover is interesting for the search for life and the preservation of biosignatures, because it is a sedimentary rock that would have formed during the evaporation of the water that was in this crater.
Scientists have made another discovery in this crater. This is a place where there must have been an ancient lava lake or magma chamber, because they discovered igneous rocks at the bottom, a sign of active volcanism at some point in Mars’ history. Also called magmatic rocks, they form during the cooling of lava. It appears that in the case of this Martian crater, olivine crystals formed during the slow cooling of the magma. At one point, the water flowed in abundance and eroded the rock. The researchers are trying to determine if this rock formed in the lava lake or in an underground magma chamber that was once exposed to water.
Perseverance sampled this magmatic rock for analysis on Earth when the samples return in 2033. At that time, it will be possible to determine the age of the Red Planet’s surface.
(Also read: MARS: Soil samples can contaminate the Earth?)
“NASA’s Perseverance Rover Investigates Mars’ Geologically Rich Terrain,” NASA Mars Science Exploration Program, September 15, 2022, https://mars.nasa.gov/news/9261/nasas-perseverance- rover-investigates-geologically-rich-mars-terrestrial/