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A new study led by the University of Colorado Boulder has shown that gases often seen as indicators of life on distant planets may not be as reliable as previously thought. Researchers managed to recreate dimethyl sulfide - a molecule traditionally associated with biological activity - in a lab without the involvement of living organisms.
Published in 'Astrophysical Journal Letters', the s by Clarence Oxford
Los Angeles CA (SPX) Sep 25, 2024
A new study led by the University of Colorado Boulder has shown that gases often seen as indicators of life on distant planets may not be as reliable as previously thought. Researchers managed to recreate dimethyl sulfide - a molecule traditionally associated with biological activity - in a lab without the involvement of living organisms.
Published in 'Astrophysical Journal Letters', the study demonstrates that organic sulfur compounds like dimethyl sulfide can form in the absence of life, which could shift how scientists interpret biosignatures on exoplanets. The experiment, conducted by Nate Reed and Ellie Browne from CU Boulder's Cooperative Institute for Research in Environmental Sciences (CIRES), revealed that light interacting with gases can create this molecule, which is often made by marine microbes on Earth.
"The sulfur molecules that we're making are thought to be indicators of life because they're produced by life on Earth," Browne explained. "But we made them in the lab without life - so it might not be a sign of life, but could be a sign of something hospitable for life." While these organic sulfur compounds may not be definitive markers of life, they could still indicate metabolic potential.
Exploring Exoplanets
The study was motivated by findings from NASA's James Webb Space Telescope, which has been capturing images of exoplanets since its launch in 2009. One of the telescope's missions is to detect biosignatures in distant atmospheres to assess the possibility of life. The CU Boulder team focused on sulfur-containing organic molecules, which are often secondary products of living organisms.
"One of the big findings of the paper that we saw was dimethyl sulfide," Reed stated. "That one was exciting, because it's been measured in exoplanetary atmospheres, and it's thought previously to be a sign of life living on the planet."
In the study, researchers replicated planetary atmospheres in a lab by exposing gases like methane and hydrogen sulfide to UV light, which resulted in the creation of biosignature molecules. However, Reed cautioned that their results are limited to a single type of atmospheric condition and urged further studies across different environments.
Looking ahead, the team hopes their work will inspire more research into fundamental chemical reactions, especially those involving sulfur. Browne emphasized the importance of cautious interpretation when studying biosignatures, adding, "The atmosphere is really good at making a whole bunch of different molecules, and we've found that just because it can be made in a lab, doesn't mean it's not a source."
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