Detecting isoprene in an exoplanet's atmosphere could reveal life on its surface, according to MIT researchers. The study is published in Astrobiology.
Astronomers have confirmed more than 4,300 exoplanets, with several thousand candidates awaiting verification. The goal now is deeper characterization of these distant worlds.
The James Webb Space Telescope (JWST) will accelerate this once operational. By analyzing infrared spectra from transiting exoplanets passing in front of their stars, it will uncover atmospheric molecular compositions.
These insights will refine habitability assessments and enable detection of biosignatures—chemical markers of life and biological processes.
Astrobiologists have compiled potential biosignatures like oxygen from photosynthetic organisms, carbon dioxide they metabolize, essential water, and methane from decaying organics.
A Massachusetts Institute of Technology (MIT) team led by Dr. Zhuchang Zhan proposes adding isoprene (C5H8) to the list.
Like methane, isoprene is an organic hydrocarbon and secondary metabolite produced by bacteria, plants, animals, and more.
Earth's isoprene rivals methane in abundance but degrades via oxygen and radicals. The team targets anoxic atmospheres of hydrogen, carbon dioxide, and nitrogen—mirroring primordial Earth.
From 4 to 2.5 billion years ago, Earth likely teemed with isoprene before the Great Oxidation Event. Early microbes produced oxygen that saturated minerals, accumulating in the air and proving toxic to anaerobes and isoprene alike.
Isoprene could flag planets poised for major evolutionary leaps, seeding new life forms.
Spotting isoprene will challenge even JWST. It requires production 10 to 100 times early Earth's rate, amid spectral overlap with other hydrocarbons.
Mid-infrared telescopes excel here. Beyond JWST, the Roman Space Telescope—Hubble's successor, launching 2025—is well-suited.
