Researchers at the University of Colorado Boulder have made a surprising discovery that challenges our understanding of potential indicators of life on other planets. By creating a type of organic sulfur compound, often seen as a sign of life, in a chemistry lab without any organisms present, the study suggests that these so-called ‘biosignatures’ may not be as reliable as previously thought.
Rethinking Biosignatures
If you measure the atmosphere, then one of the ways we think of them searching for life is looking at atmospheric properties of far away planets. In some cases, telescopic images are able to reveal the presence of gases that could be indicative of life and habitability.
But a new study led by researchers at the University of Colorado Boulder suggests exactly the opposite. Using a reaction chamber, the researchers produced dimethyl sulphide – an organic sulfur compound frequently emitted by marine microbes — using only light and gases commonly found in planet atmospheres. This means that the existence of this compound might not be a very reliable marker for life, since it can arise without being made by any living thing.
Defying the System
Creating dimethyl sulfide in the lab was a first—or “a big win over nature,” as the researchers, including CIRES Visiting Fellow Nate Reed and CIRES Fellow and associate professor of chemistry Ellie Browne, put it—but their findings are even more significant for astrobiology.
“The sulfur molecules that we are making are always life markers, they are products of life on Earth,” Browne said. We made them in the lab without life, wondered about another scientist — so it’s not proof of life, but maybe habitable by something that is alive.
In other words, the compound sulphur can be considered as a biomarker but because it contains organic presence that had been previously thought of as only being able to form in life before we actually knew about examples of it forming through abiotic process is also no conclusive evidence. The detection implies important consequences for the James Webb Space Telescope (JWST), which aims to acquire images of exoplanets and study their atmospheres.
Conclusion
Researchers at the University of Colorado Boulder, however, argue in a new study that gases often associated with life can also be produced by nonbiological processes based solely on chemistry. The researchers’ work reinvents these so-called biosignatures, showing that we may have to rethink the way we look for life on other planets by demonstrating how they can be created in a lab without any living organisms. While the quest for potentially habitable planets is ongoing, these results underscore the need to do basic laboratory studies and obtain better knowledge of all possible complex chemical reactions under a variety of planetary conditions.
