Researchers have identified traces of fossilized life in terrestrial gypsum deposits, opening a new avenue for the search for biosignatures on Mars. This discovery, made using a state-of-the-art instrument, could impact future exploration missions to the Red Planet.
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An international team, led by the University of Bern, used a miniaturized mass spectrometer to detect fossilized microorganisms in gypsum deposits in Algeria. These deposits, formed millions of years ago, resemble those observed on Mars, providing an ideal study ground to simulate Martian conditions. The results, published in
Frontiers in Astronomy and Space Sciences, suggest that similar instruments could be used to search for traces of past life on Mars.
Gypsum, a promising fossil trap
Gypsum, a mineral formed by the evaporation of water, has a unique ability to preserve traces of life. On Earth, researchers have discovered fossilized microbial filaments in deposits dating back to the Messinian salinity crisis, a period when the Mediterranean Sea nearly dried up. These structures, associated with minerals like dolomite and clay, indicate past biological activity.
On Mars, similar gypsum deposits could harbor biosignatures dating back to the time when the planet was wet and warm. Researchers believe that these minerals, formed rapidly, could have trapped microorganisms before their decomposition, thus preserving clues of ancient life. This hypothesis strengthens the scientific interest in future missions.
A - Crystalline facies of gypsum and sample handling.
B - Twin selenite crystals and small crystals showing the dark reentrant angle (dotted black lines).
C - Petrographic thin section of the reentrant angle of the twinned selenite crystal marked in blue in A, showing very turbid laminae (vTL), turbid laminae (TL), and clear laminae (LL).
D - Small thin section of turbid laminae mounted on the LIMS holder with a copper tape. Sample coated with gold on the LIMS holder. An instrument ready for Martian exploration
The LIMS mass spectrometer, developed at the University of Bern, has demonstrated its effectiveness in detecting biosignatures in terrestrial samples. This instrument, designed to operate in space, could be integrated into Martian rovers or landers. It would allow for on-site analysis of the chemical composition of rocks, searching for traces of fossilized life. Its miniaturization and precision make it an essential tool for future exploration missions.
Researchers tested this technology in gypsum deposits in Algeria, a geological site analogous to those on Mars. The results are encouraging: LIMS identified microbial filaments and minerals associated with life, such as dolomite and clay. These elements, often linked to biological activity, reinforce the hypothesis that similar conditions could exist on Mars. This success validates the method and paves the way for its use in extraterrestrial environments.
In addition to its ability to detect biosignatures, LIMS is designed to withstand the extreme conditions of space. Its integration into a Martian mission would allow for rapid and precise analysis of samples without the need for return to Earth. This technological advancement represents a major step in the quest for evidence of past life on Mars, while reducing the costs and risks of space missions.
To go further: What is a biosignature?
A biosignature is a chemical, physical, or morphological trace left by living organisms. It can take the form of organic molecules, microscopic structures, or specific minerals that indicate the past or present presence of life. On Mars, scientists are searching for these clues in rocks, soils, or mineral deposits, such as gypsum, which could have preserved traces of ancient life.
Biosignatures are not limited to visible fossils. They also include chemical compounds, such as amino acids or lipids, which are often associated with biological processes. For example, the presence of certain organic molecules or minerals like dolomite, formed in the presence of microorganisms, can constitute indirect evidence of life. However, it is important to distinguish these signs of biological origin from those produced by abiotic processes.
The search for biosignatures on Mars relies on instruments capable of analyzing the chemical composition and structure of rocks at a microscopic scale. Tools like the LIMS mass spectrometer allow for the detection of these traces with high precision. However, confirmation of life often requires multiple independent methods to avoid false positives, a major challenge in space exploration.
Article author: Cédric DEPOND