Detectable signal that reveals life on planets outside our solar system

2023-12-29 18:15:19

Scientists have concluded that the best chance of finding liquid water, and even life, on other planets is to search their atmospheres for the absence of a certain chemical characteristic, rather than the presence of others.

The team, made up of, among others, Amaury HMJ Triaud, from the University of Birmingham in the United Kingdom, and Julien de Wit, from the Massachusetts Institute of Technology (MIT) in the United States, proposes that if a planet of terrestrial geological type has With substantially less carbon dioxide in its atmosphere compared to other planets of the same type in the same solar system, this could be a sign of the existence of liquid water (and possibly life) on the surface of that planet.

What’s more, the absence of this new signature is verifiable by the James Webb Space Telescope (JWST). Although other signals of habitability have been proposed, these are difficult, if not impossible, to measure with current technology. The team claims that this new signal, of poor carbon dioxide content, is the only sign of habitability that is reliably detectable today.

Venus, Earth and Mars share similarities, as all three are rocky planets and orbit within a band around the Sun that is relatively temperate in terms of the solar radiation that reaches there. Earth is the only planet of the trio that currently hosts liquid water. And it also has much less carbon dioxide in its atmosphere than Venus or Mars.

“We assume that these planets were created in a similar way, and if we see a planet with much less carbon now, it must have gone somewhere,” Triaud argues. “The only process that could remove that much carbon from an atmosphere is a strong water cycle involving oceans of liquid water.”

In fact, Earth’s oceans have played an important and sustained role in absorbing carbon dioxide. Over hundreds of millions of years, the oceans have absorbed an enormous amount of carbon dioxide, almost equal to what persists today in the atmosphere of Venus. This planetary-scale effect has left Earth’s atmosphere significantly depleted of carbon dioxide compared to those of its planetary neighbors.

Artistic recreation of an exoplanet (planet in our solar system). (Illustration: Jorge Munnshe for NCYT from Amazings)

The study is titled “Atmospheric carbon depletion as a tracer of water oceans and biomass on temperate terrestrial exoplanets.” And it has been published in the academic journal Nature Astronomy. (Source: NCYT from Amazings)