Billions of years ago, Mars was likely much different than it is today. Scientists think it was warmer and wetter, with a thicker atmosphere. These conditions could have supported simple microbial life. However, there is no direct proof that life ever existed there.
NASA rovers have found organic molecules in Martian rocks. But these compounds can also form without life. In 2025, tiny dark spots were seen on a rock in Jezero Crater. These spots looked like leopard spots and could be from either organic matter or microbes. Researchers collected a sample, but NASA removed the sample return mission from its plans due to funding issues.
The European Space Agency's (ESA) Rosalind Franklin rover is trying a new way to find life. It will arrive on Mars in 2030. The rover will explore the Oxia Planum region, which is rich in clay. Scientists believe water once flowed there. The main goal is to find organic molecules that could show signs of ancient life.
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Start Your News DetoxLooking for Life with MOMA
Scientists from the Max Planck Institute for Solar System Research, the University of Göttingen, and the University of Côte d’Azur have been improving the Mars Organic Molecule Analyzer (MOMA). This instrument was developed by the Max Planck Institute and will be on the Rosalind Franklin rover. The team recently tested its method using a Martian meteorite.
It is very hard to prove that life once existed on Mars, even with advanced technology. Researchers need to figure out if ancient organic molecules came from living things or from natural chemical processes.
The team is focusing on two stable hydrocarbons: pristane (C19H40) and phytane (C20H42). On Earth, both come from living organisms and are found in petroleum. This makes them good candidates for finding ancient biological activity.
Guillaume Leseigneur, an MPS scientist and lead author of the new study, said that if life existed on Mars, molecules like pristane and phytane could be important signs that have lasted until today.
Chirality and Extraterrestrial Life
Pristane and phytane are also chiral. This means they exist in two mirror-image forms, like a left and right hand. These forms are called enantiomers. Uwe Meierhenrich, a co-author from Côte d’Azur University, noted that chirality is a valuable tool in the search for past extraterrestrial life.
In living organisms, chiral molecules almost always appear in only one of these mirror forms. Scientists expect the same for any life beyond Earth because of how living things reproduce. Molecules made through nonbiological processes, however, should have both mirror forms in roughly equal amounts.
How MOMA Detects Molecules
The Rosalind Franklin rover can tell the difference between molecules with different chiral forms using MOMA. This instrument has a gas chromatograph, a mass spectrometer, small furnaces, and a laser. Rock samples are heated, and the released gases are analyzed.
The gases then go through special tubes. Each mirror-image form interacts differently with the tube coating, so they move at different speeds. This allows MOMA to separate and identify them.
In recent tests, the team used MOMA's tubes to separate pristane and phytane for the first time. These compounds are very resistant to chemical reactions, making this a difficult task. Fatma Yesil Sahan from the MPS, a co-author and MOMA team member, explained that chiral separation of pristane and phytane needs high sensitivity and accuracy, which MOMA can achieve.
The researchers used pieces of the Murchison meteorite, which fell in Australia in 1969, as a stand-in for Martian rock. This meteorite contains many organic molecules. Some are original, and others are from later biological contamination, like material picked up from Earth. The team thought pristane and phytane would be from contamination.
Meteorite Contamination
The measurements showed something unexpected. In the Murchison meteorite, all chiral forms of pristane and phytane were found in equal amounts. This is not what would be expected from living matter at the discovery site. The researchers believe the contamination happened as the meteorite passed through Earth’s atmosphere and picked up aerosols from burning fossil fuels.
This idea is supported by comparing tests on pristane and phytane found in oil shales. These rocks contain a precursor to petroleum. Manuel Reinhardt from the University of Göttingen, a co-author, said that petroleum forms in these rocks over millions of years deep underground, with heat and pressure. These conditions erase the usual chiral imbalance. This could explain why all chiral forms of pristane and phytane were equal in the Murchison meteorite.
The team sees this experiment as more than just a successful test for MOMA's future work on Mars. The findings also bring up new questions about where organic molecules in meteorites come from and how increasing petroleum contamination in Earth’s atmosphere might affect them.
Deep Dive & References
Racemic isoprenoids in the Murchison meteorite derive from petroleum-based aerosol pollutants - Earth and Planetary Science Letters, 2026
