NASA reveals new evidence of organic molecules on Mars – 07/13/2023 – Science

Evidence is mounting for what could be a large amount of organic molecules — a potential hint of life — on Mars. New discoveries from NASA’s Perseverance rover suggest the presence of a diversity of rocks at a site where a lake once existed.

The most recent evidence comes from an instrument called the Sherloc mounted on the rover’s robotic arm, a six-wheeled vehicle that allows detailed mapping and analysis of organic molecules. Researchers are reporting Sherloc findings at 10 locations in two geological formations at the bottom of Jezero Crater.

They obtained evidence indicating the presence of molecules in several rock samples, including some collected for possible return to Earth for further analysis. The researchers noted that evidence from such molecules is not proof of past or current life on Mars, and that non-biological processes are still a more likely explanation.

“Organics are the molecular building blocks of life as we know it, but they can also form from geological processes not directly related to life. are associated,” said astrobiologist Sunanda Sharma, from NASA’s Jet Propulsion Laboratory in California, lead author of the research published this Wednesday (12) in the journal Nature.

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 February 2021 in Jezero Crater, an area in the planet’s northern hemisphere that was once flooded with water and is home to an ancient lake basin.

Mars wasn’t always the inhospitable place it is today — it had liquid water on its surface in the distant past. Scientists suspect that microbial life may have existed in Jezero Crater. They believe that river channels flowed through the crater wall and created a lake more than 3.5 billion years ago.

Signals of organic molecules were detected in the 10 locations that Sherloc—short for Scanning Habitable Environments with Raman and Luminescence for Organics and Chemicals—studyed at the bottom of the crater. The rocks were igneous—volcanic in formation.

Sherloc employs cameras, a laser and instruments called spectrometers that analyze wavelengths of light to look for organic molecules that could be signs of past microbial life. Adhering to the Sherlock Holmes theme, Sherloc is assisted by Watson, a color camera to obtain close-up images of rock graining and surface textures.

The researchers don’t know the specific organic compounds Sherloc detected, but they have some clues. Study co-author Ryan Roppel, a graduate student in chemistry at the University of Pittsburgh, said the chemical signatures could come from compounds like benzene or naphthalene (or mothballs).

“On Earth, these are quite common in crude oil, which has a biotic origin, but we can also form them synthetically through various chemical reactions,” Roppel said.

“The concentrations we detect are generally low, but we observe signals associated with organics in almost all the rocks we sample,” he added.

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

Signals of organic molecules were first detected on Mars in 2015 by another rover, called Curiosity, followed by more evidence in subsequent years. With Perseverance now detecting possible signatures of organic molecules, evidence is accumulating that organic molecules may be relatively common on Mars, albeit at low levels.

The researchers remain cautious about the findings.

“There are biotic and abiotic mechanisms that can form organic molecules. Interplanetary dust, falling meteorites or water-rock interactions can produce organics abiotically,” said Roppel. “On the other hand, ancient life could also produce these organics, but this is usually the hypothesis of last resort. We need to rule out all abiotic mechanisms before jumping to the conclusion that any organic molecules are a sign of life.”

^{Translated by Luiz Roberto M. Gonçalves}