The search for life has become one of the holy grails of science. With the increasing number of exoplanet discoveries, astronomers are hunting for a chemical that can only be present in the atmosphere of a planet with life! A new paper suggests that methyl halides, which contain one carbon and three hydrogen atoms, may just do the trick. Here on Earth they are produced by bacteria, algae, fungi and some plants but not by any abiotic, non biological processes. There is a hitch, detecting these chemicals is beyond the reach of current telescopes.
A team of researchers from University of California, Riverside have released a paper that discusses detecting certain gases in exoplanet atmospheres using the James Webb Space Telescope (JWST.) The paper was authored by planetary scientist Michaela Leung and astrobiologist Eddie Schwieterman and they explain however that exoplanets like Earth are just too small and dim for JWST to observe directly.
Artist impression of the James Webb Space Telescope (Credit : NASA)
There is no doubt that JWST is revolutionising the study of exoplanets by enabling the analysis of their atmospheres for potential signs of life. Using its advanced infrared instruments, JWST can detect gases like water vapour, carbon dioxide, and methane, which may indicate habitable conditions. By observing how a planet’s atmosphere interacts with starlight, it’s possible to infer its composition and climate, unfortunately we are not quite there yet for Earth-sized planets.
Earth-sized exoplanets are just too dim and small to enable atmospheric analysis, even for JWST. In particular and as proposed by Leung and Schwieterman, methyl halides are gases worthy targets for a search. They consist of a methyl group attached to a halogen atom, primarily produced on Earth by bacteria, algae, fungi, and plants and, if they can be found in exoplanetary atmospheres, could reveal life! Even if methyl halides are discovered in atmospheres of ocean-covered worlds (Hycean planets) they may still reveal microbial life.
“Unlike an Earth-like planet, where atmospheric noise and telescope limitations make it difficult to detect biosignatures, Hycean planets offer a much clearer signal,” – Eddie Schwieterman, UCR astrobiologist.
The duo believe that searching for methyl halides on Hycean planets is the most promising strategy at this current time taking into consideration the current technological limitations. The gases are produced by life forms on Earth but they exist in only low concentrations in our atmosphere. It’s thought that the atmospheric composition of Hycean worlds, combined with their orbits around red dwarf stars, could allow methyl halides to build up in detectable amounts. This makes them an excellent target for JWST in the search for alien life.
Europa, one of the Galilean satellites of Jupiter has a global sub-surface ocean (Credit : NASA)
The study expands on previous research into biosignature gases, highlighting methyl halides as particularly useful due to their strong infrared signatures and potential to accumulate in hydrogen-rich atmospheres. While JWST is currently the best tool for detecting these gases, future missions like the proposed European LIFE mission could make the search even easier. If launched in the 2040s, LIFE could confirm the presence of these biosignatures in less than a day. While direct sampling of exoplanet atmospheres is currently impossible, advancements in telescope technology and research may one day, perhaps soon, help to answer the question ‘are we alone in the Universe?’
Source : Signs of alien life may be hiding in these gases