Mars Rover curiosity brought this selfie in October 2019 after having perforated the rock twice in its position. Credit: NASA/JPL-CALTECH/MSSS
Mars Curiosity Rover has found the largest organic molecules on the red planet. Organic molecules are the bricks of life, although they can also be produced by geological processes. Although currently there is no way to demonstrate whether these particular molecules have been made up of processes associated with life, their own discovery shows that a complex chemistry has occurred on Mars.
While the objectives of curiosity are not the direct discovery of life on Mars, he was commissioned to study the potential for life on the red planet. So far, this mission has painted a complex picture of the history of the planet, including overwhelming tests for water through large geological time bands. This water is what has allowed to develop a complex chemistry – and scientists have not yet excluded the possibility that life has also increased at a certain point, even if it has yet to be demonstrated.
Pierce
The newly discovered molecules are dean, Undecano and Dodecano, called respectively for the atoms of 10, 11 and 12 that contain each one. They could, in turn, be broken by even larger carboxylic molecules (containing carbon, oxygen and hydrogen), but the analysis of the curiosity champion on Martes (Sam) is not built to identify these large molecules. In living cells, carboxylic or fatty acids are omnipresent as part of most cell walls. But these molecules can also occur through abiotic processes, in particular around hydrothermal air intakes.
Curiosity discovered the molecules when he practiced in a Cumberland nicknamed rock in 2013, one of the two champions collected in Yellowknife Bay inside Gale Crater, where the Rover spent his time on Mars. Yellowknife Bay is believed to be an extinct lake, with millions of years of history stratified in the rocks that once laid underwater or were deposited by floods and escaping liquid.
The Cumberland champion has been studied several times, using Sam’s chromatographer mass spectrometer, who warms the champions to reveal what they are made. In 2015, Caroline Freissinet, researcher of the French national center for scientific research in the laboratory for atmospheres, observations and space, discovered chlorobenzene in the sample, marking the first organic molecule found on Mars. Freissinet is also the main author of the new document that describes in detail the largest organic molecules, which was published on March 24 in Proceedings of the National Academy of Sciences.
A well preserved treasure
In nature, large molecules are also some of the most delicate. The smaller molecules are generally more stable and closely connected, while the larger molecules are more inclined to destruction by radiation, heat or other energy processes. At the same time, large molecules indicate a more complex chemistry, since the processes that build them tend to require more time and require more exotic situations than it does to create basic compounds.
Scientists are still divided on the exact time sequence that brought from the wet past of Mars, when it was more similar to the ancient earth, to its current sterile status. But it is clear that the ancient Mars had environments to create these more complex molecules, through interactions of water and heat on a more dynamic world or biological processes.
But the first step to answer these questions is to find the complex molecules in question. Scientists had not been sure of how achievable this goal was; Even if the other discoveries of curiosity have shown that Ancient Mars was a wet and active world, the large molecules created in those days could have been divided for a long time under the harsh radiation that the planet has suffered in the last billions of years.
So the discovery of these large molecules in the Cumberland champion is an advantage for researchers. First of all, it shows that Mars had an even more complex chemistry that scientists have occurred so far.
Amy Williams, associate professor at the University of Florida at the Department of Geological Sciences, was co -author of the study. “If the molecules of this study had been generated inhabitically,” he says, “they could have been delivered by carbonaceous meteors that bombed Mars in the ancient past or in the ancient Martian hydrothermal air intakes”. But, he says, “abiotic fatty acids tend to have shorter carbon chains and lower abundance of longer lengths of the longer chain. These results are intriguing because they find themselves at the turn of the range of lengths of the carbon chain generated both to dress and from life as we know it.”
Although these molecules have been produced without the presence of life, he paints the picture of a more interesting and dynamic Mars than previously made.
Furthermore, if curiosity could identify these molecules, it means that other large molecules could also be out there for the discovery. Often, large molecules like these and proteins created by life are easily destroyed by radiation over time. But if these molecules have survived – and scientists think they have been created about 3.7 billion years ago – then it means that even the actual biosignures may have survived, even if this life has died billions of years ago. This substantially increases the temporal sequence on which scientists can plausibly seek signs of life spent on Mars.
“Before the Sam tool detected organic carbon in a storm crater starting from 2013,” says Williams, “scientists had not definitively detected the indigenous organic carbon on the surface of Mars. From that moment, we continued to discover a greater diversity of the molecules, including this discovery with the major molecules.
“Our study shows that, even today, analyzing the champions of Mars we could detect the chemical signatures of past life, if ever existed on Mars,” said Freissinet in a press release.
NASA hopes to return samples stored in the cache of the colleague Rover of curiosity, perseverance, on earth for analysis in the 1930s. Analyzing those champions in the workshops on Earth, scientists could drastically expand their knowledge of the history of the red planet – and perhaps finally answer the question definitively if life ever existed on our neighbor.
Related: Decision nasa on Mars the reboot of the return of the sample to 2026
Note of the editor: A previous version of this story erroneously stated that the return program of the Mars sample would include samples of the Rover Curiosity.
