AGI – A new study has assessed the planetary context in which the discovery of methane in the atmosphere of an exoplanet can be considered a compelling sign of life. It was created by the University of California, Santa Cruz and published in Proceedings of the National Academy of Sciences. If life is abundant in the universe, Atmospheric methane may be the first sign of extraterrestrial life that astronomers can detect.
Although non-biological processes can generate methane, a new study by UC Santa Cruz scientists has found a number of circumstances in which a compelling case can be made for biological activity as a source of methane in a rocky planet’s atmosphere.
This is especially noteworthy because Methane is one of the few potential signs of life, or ‘biological signatures’, that can be easily detected with the James Webb Space Telescope.which will begin observations later this year.
“Oxygen is often considered one of the best biological markers, but it can potentially be difficult to detect with JWST,” said Maggie Thompson, a graduate student in astronomy and astrophysics at the University of California, Santa Cruz and lead author of the new study.
“We wanted to provide a framework for interpreting the observations, so if we see a rocky planet with methane in it, we know the other observations needed to be a convincing biosignature.”
Despite some previous studies of methane’s biosignatures, there has been no up-to-date, personalized assessment of planetary conditions necessary for methane to be a good biomarker.
The study looked at a variety of non-biological sources of methane and assessed their ability to maintain a methane-rich atmosphere. These include volcanoes. reactions in environments such as ocean ridges, hydrothermal vents and tectonic subduction zones; and the impacts of comets or asteroids.
“If you detect a lot of methane on a rocky planet, you usually need a huge source to explain it,” said co-author Joshua Krissansen-Totton, Sagan Fellow at the University of California, California.
“We know that biological activity produces large amounts of methane on Earth, and it probably also happened early on Earth as well because methane production is fairly easy to metabolize.”
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