James Webb Space Telescope Feed Post

Prebiosignature Molecules Can Be Detected in Temperate Exoplanet Atmospheres with JWST Published: 6/5/2023 5:05:07 PM Updated: 6/5/2023 5:05:07 PM

Paper abstract: The search for biosignatures on exoplanets connects the fields of biology andbiochemistry to astronomical observation, with the hope that we might detectevidence of active biological processes on worlds outside the solar system.Here we focus on a complementary aspect of exoplanet characterisationconnecting astronomy to prebiotic chemistry: the search for moleculesassociated with the origin of life, prebiosignatures. Prebiosignature surveysin planetary atmospheres offer the potential to both constrain the ubiquity oflife in the galaxy and provide important tests of current prebiotic synthesesoutside of the laboratory setting. Here, we quantify the minimum abundance ofidentified prebiosignature molecules that would be required for detection bytransmission spectroscopy using JWST. We consider prebiosignatures on fiveclasses of terrestrial planet: an ocean planet, a volcanic planet, apost-impact planet, a super-Earth, and an early Earth analogue. Using a novelmodelling and detection test pipeline, with simulated JWST noise, we find thedetection thresholds of hydrogen cyanide (HCN), hydrogen sulfide (H2S),cyanoacetylene (HC3N), ammonia (NH3), methane (CH4), acetylene (C2H2), sulfurdioxide (SO2), nitric oxide (NO), formaldehyde (CH2O), and carbon monoxide (CO)in a variety of low mean molecular weight (<5) atmospheres. We test thedependence of these detection thresholds on M dwarf target star and the numberof observed transits, finding that a modest number of transits (1-10) arerequired to detect prebiosignatures in numerous candidate planets, includingTRAPPIST-1e with a high mean molecular weight atmosphere. We find that theNIRSpec G395M/H instrument is best suited for detecting most prebiosignatures.