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Did life exist on Mars? AI might help us find answers

Scientists have discovered a simple and reliable machine learning test that could look for signs of past or present life on other planets

This image taken by Nasa's Perseverance rover on Aug. 6, 2021, shows the hole drilled in a Martian rock in preparation for the rover's first attempt to collect a sample.(Nasa/JPL-Caltech)

By Nitin Sreedhar

LAST PUBLISHED 26.09.2023  |  12:00 PM IST

The recent Nasa Osiris-rex asteroid sample return mission has the astrobiology community excited, as scientific researchers attempt to learn new things – and secrets – about the solar system. Artificial intelligence (AI) could play a key role in this journey.

Scientists have discovered a simple and reliable AI-based test to look for signs of past or present life on other planets. This machine learning technique could reveal a sample’s biological or non-biological origin with 90% accuracy. In the journal Proceedings of the National Academy of Sciences, a 7-member team, funded by the John Templeton Foundation and led by Jim Cleaves and Robert Hazen of the Carnegie Institution for Science, reported that, with 90% accuracy, their artificial intelligence-based method distinguished modern and ancient biological samples from those of abiotic origin, a Carnegie Science press release said.


Also read: Scientists have found a new type of ancient crater lake on Mars

“This routine analytical method has the potential to revolutionize the search for extraterrestrial life and deepen our understanding of both the origin and chemistry of the earliest life on Earth," Dr. Hazen says in the release. “It opens the way to using smart sensors on robotic spacecraft, landers and rovers to search for signs of life before the samples return to Earth."

The new test, for instance, could reveal the history of ancient rocks on Earth, and possibly that of samples already collected by the Mars Curiosity rover’s Sample Analysis at Mars (or SAM) analytical instrument, the release explains. The Curiosity rover has been on the Martian surface since August 2012 where it is, among other things, studying the climate and geology of Mars.

This new analytical method does not rely on identifying just a specific molecule or group of compounds in a sample. The researchers have instead demonstrated that AI can differentiate biotic (consisting of living organisms) from abiotic (physical rather than biological; not derived from living organisms.) samples by detecting subtle differences within a sample’s molecular patterns as revealed by pyrolysis gas chromatography analysis (which separates and identifies a sample’s component parts), followed by mass spectrometry (which determines the molecular weights of those components), the release explains.

To do so – predicting a new sample’s origin -- the AI model was trained using vast multidimensional data from the molecular analyses of 134 known abiotic or biotic carbon-rich samples. With approximately 90% accuracy, AI successfully identified samples that had originated from living things, such as modern shells, teeth, bones, insects, leaves, rice, human hair, and cells preserved in fine-grained rock, remnants of ancient life altered by geological processing (for instance, coal, oil, amber, and carbon-rich fossils), or samples with abiotic origins, such as pure laboratory chemicals (e.g., amino acids) and carbon-rich meteorites, the release adds.

The study’s authors said that until now the origins of many ancient carbon-bearing samples have been difficult to determine because collections of organic molecules, whether biotic or abiotic, tend to degrade over time. Surprisingly, the release adds, in spite of significant decay and alteration, the new analytical method detected signs of biology preserved in some instances over hundreds of millions of years.


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“I think this new study is very exciting! It is a new avenue of research to explore as it appears to discriminate abiotic from biotic organic matter based on its molecular complexity and could potentially be a fantastic tool for astrobiology missions. It would also be very interesting to test this new method on some of the oldest putative and debated traces of Earth life as well as on modern and fossil organisms from the three domains of life! This might help to solve some hot debates in our community," Emmanuelle J. Javaux, head, Early Life Traces and Evolution-Astrobiology Lab, and director, Astrobiology Research Unit, University of Liège, Belgium, said in the news release.

Recently, researchers also described another novel method of analyzing Mars’ gravitational force to support the idea that the planet once had an extensive northern ocean.

Also read: Mars once had life-supporting climate: Nasa