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Organic matter was found on Mars in soil samples taken from 3 billion year old mudstone in the Gale crater by the Curiosity rover, NASA reported on Thursday. The researcher also detected methane in the Martian atmosphere
The search for life outside the Earth focuses on the building blocks of life as we know it, including organic compounds and molecules – although they can exist without life. Organic matter can be one of several things: a document detailing old life, a source of food for life or something that exists in place of life.
Regardless of its purpose, these works serve as chemical clues for researchers on Mars.
Methane is considered the simplest organic molecule. It is present in other places of our solar system that could accommodate life, such as Saturn and the moons of Jupiter Enceladus, Europa and Titan. And if life exists elsewhere, it can be very different or even different from the way we understand life on Earth.
The new discoveries are also detailed in two studies published Thursday in the journal Science. Together, researchers believe these discoveries are "breakthroughs in astrobiology".
"We have significantly expanded our search for organic compounds, which is fundamental in the search for life," said Paul Mahaffy, author and director of Solar. Division of System Exploration at NASA's Goddard Spaceflight Center
Both studies rely on small detections of atmospheric methane and ancient organic compounds on Mars. These detections have either caused debate or lack of context, according to the researchers.
But Curiosity data provides a clearer and more conclusive picture of the conditions and processes on Mars – and how it could have been on the red planet Billions of years ago, when conditions were more conducive to the life.
"With these new discoveries, Mars is telling us to stay the course and look for evidence of life," said Thomas Zurbuchen, associate director of the Science Missions Directorate. at NASA headquarters. "I am confident that our ongoing and planned missions will unlock even more amazing discoveries on the red planet."
Finding clues under the surface
We explored the surface of Mars in the hope of understanding the red planet since NASA's Viking mission in the 1970s. The Viking project was the first mission to land safely on the Martian surface and to return images.
Although the two undercarriages and their instruments can detect signs of life or organic compounds in samples taken from the surface, this has not happened.
Decades later, Viking helped to inspire the instruments of Martian rovers today. And the curiosity dug a little deeper beneath the surface, which is dynamited, to see what stories the soil had to tell.
Curiosity sampled sites by digging five centimeters below the surface in Gale Crater, where the rover landed. in 2012. The 96-mile crater, named for Australian astronomer Walter F. Gale, was probably formed by the impact of meteors between 3.5 to 3.8 billion years ago. . He probably held a lake, and now includes a mountain.
The rover was able to heat the samples between 932 and 1508 degrees Fahrenheit and study the organic molecules released by gas analysis. Organic and volatile molecules, comparable to organic-rich sedimentary rock samples on Earth, included thiopene, methylthiophene methanethiol and dimethylsulfide.
They do not come out of the tongue, but researchers believe that fragments of larger molecules were present on Mars billions of years ago. And the large amount of sulfur in the samples is probably the way they lasted so long, the researchers said. Drilling below the surface, rather than sampling what was at the top like the Viking, also helped.
The potential contaminants have been analyzed and taken into account, so the results are the most conclusive.
"The Martian surface is exposed to radiation from space," said Jen Eigenbrode, author of the study and research scientist at the Goddard Space Flight Center. "Radiation and aggressive chemicals break down the Organic matter: Finding old organic molecules in the first 5 centimeters of the rock that was deposited while Mars was habitable is auspicious for learning the history of organic molecules on Mars.
Methane in the Air
In five years, Curiosity used its tunable laser spectrometer to measure methane in the atmosphere of the Gale crater. Previously, researchers could not understand why the little methane detected in the Martian atmosphere varied. With five years of data coming from one place, they now have answers.
There is a seasonal variation in methane that is repeated, which means that methane is released from the Martian surface or subsurface reservoirs. The methane could even be trapped in water-based crystals below the surface.
Methane is a potent greenhouse gas, and it could have supported a climate that supported lakes on Mars. This could even happen under the surface now, the researchers said. The release of methane is an active process on Mars, which could suggest new things about what's happening on the red planet.
Detecting this organic molecule in the atmosphere, combined with the discovery of organic compounds in the soil, has strong implications for potential life on Mars in its past.
Gale Crater was probably habitable 3.5 billion years ago, based on what Curiosity showed us. Then the conditions would have been comparable to the Earth. It is also when life was evolving on our own planet.
Knowing that these molecules and compounds were present, gives a new force to the idea that life was born or existed on Mars and that more work of Martian rovers can discover NASA's InSight Lander Launcher, launched on May 5th, will land on Mars on November 26th. His two-year mission will explore Mars to see if he is "geologically alive" or active beneath the surface. For example, scientists want to know if there are "tremors of Mars". And the Mars 2020 robot, which is expected to be launched in July 2020, may be able to help one day recover soil samples from Mars.
"Are there signs of life on Mars?" asked Michael Meyer, principal investigator for the Mars Exploration Program at NASA's headquarters. "We do not know, but these results tell us that we are on the right track."
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