New Evidence of Organic Molecules Found on Mars by NASA’s Rover

Evidence is mounting of what may be a wealth of organic molecules on Mars, with new findings by NASA’s Perseverance rover indicating their diversity in rocks where a lake once existed.

The latest evidence comes from Sherlock, an instrument mounted on the six-wheeled rover’s robotic arm, which enables detailed mapping and analysis of organic molecules. Researchers report Sherlock findings from 10 locations in two geologic formations on the Jezero Crater floor.

They obtained evidence indicating the presence of organic molecules in several rock samples, some of which were collected to be returned to Earth for future analysis. The researchers noted that evidence of such molecules is not proof of past or present life on Mars, and non-biological processes are more likely to explain.

„Organisms are the molecular building blocks of life as we know it, but can also be formed from geological processes not directly related to life. We see many signals of variation in crater floor textures and their associated minerals,” said Sunanta Sharma, an astrophysicist at NASA’s Jet Propulsion Laboratory in California, lead author of the research. Published This week in the magazine Nature.

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Perseverance, on a mission to search for evidence of ancient life on Mars and collect rock and soil samples for possible return to Earth, landed in Jezero Crater, an area in the planet’s northern hemisphere once flooded with water and houses, in February 2021. to an ancient lake basin.

Mars wasn’t always the hospitable place it is today, with liquid water on its surface in the distant past. Scientists suspect that microbes may have once lived in Jezero Crater. They believe that 3.5 billion years ago the river channels spilled over the crater wall and formed a lake.

Signals of organic molecules were detected at 10 locations, Sherlock – short for Scanning Habitable Environments with Raman and Luminescence with Organics and Chemicals – studied the crater floor. Rocks are igneous – volcanic.

Sherlock uses cameras, lasers and instruments called spectrometers that analyze light wavelengths to look for organic molecules that could be signs of past microbial life. In keeping with the Sherlock Holmes theme, Sherlock is assisted by Watson, a color camera that captures close-up images of rock grains and surface textures.

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Researchers don’t know the specific organic compounds Sherlock found, but there are some clues. Study co-author Ryan Roppel, a University of Pittsburgh graduate student in chemistry, said the chemical signatures could come from compounds like benzene or naphthalene.

„On Earth, these are most common in crude oil, which has a biological origin, but can be made synthetically through various chemical reactions,” Roppel said.

„The concentrations we detected were generally low, but we observed signals associated with organisms in every rock we sampled,” Roppel added.

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Roppel said the researchers can’t rule out that inorganic — metallic — sources could be responsible for some of the signals that suggest organic molecules.

Signs of organic molecules were first detected on Mars in 2015 by a different rover called Curiosity, followed by additional evidence in subsequent years. As diligence now detects potential signatures of organic molecules, evidence is accumulating that organic molecules may be relatively common on Mars, albeit at low levels.

Researchers are cautious about the findings.

„There are both biotic and abiotic mechanisms that can create organic molecules. Planetary dust, meteorites, or water-rock interactions can create organisms non-livingly,” Roppel said. „On the other hand, ancient life could have produced these organisms as well, but this is usually a last-resort hypothesis. We must rule out all abiotic mechanisms before we can conclude that any organic molecule is a sign of life.”