When researchers in 1996 reported they had found organic molecules nestled in an ancient Martian meteorite discovered in Antarctica, it caused quite a buzz. Some insisted the compounds were big-if-true evidence of life having existed on Mars (SN: 3/8/01). Others, though, pointed to contamination by earthly life-forms or some nonbiological origins (SN: 1/10/18).
Now, a geochemical analysis of the meteorite provides the latest buzzkill to the idea that alien life inhabited the 4.09-billion-year-old fragment of the Red Planet. It suggests instead that the organic matter within probably formed from the chemical interplay of water and minerals mingling under Mars' surface, researchers report in the Jan. 14 Science. Even so, the finding could aid in the search for life, the team says.
Organic molecules are often produced by living organisms, but they can also arise from nonbiological, abiotic processes. Though myriad hypotheses claim to explain what sparked life, many researchers consider abiotic organic molecules to be necessary starting material. Martian geologic processes could have been generating these compounds for billions of years, the new study suggests.
"These organic chemicals could have become the primordial soup that might have helped form life on [Mars]," says Andrew Steele, a biochemist from the Carnegie Institution for Science in Washington, D.C. Whether life ever existed there, however, remains unknown.
[...] Though the work doesn't bring us any closer to proving or disproving the existence of life on Mars, identifying abiotic sources of organic compounds there is crucial for the search, Steele explains. Once you've figured out how Martian organic chemistry acts without meddlesome life, he says, "you can then look to see if it's been tweaked."
A. Steele, L. G. Benning, R. Wirth, A. Schreiber, et al. Organic synthesis associated with serpentinization and carbonation on early Mars, Science (DOI: https://www.science.org/doi/10.1126/science.abg7905)