Life In Space: Exoplanet Closest To Earth Likely Can't Support Life

An exoplanet sitting in the habitable zone of a star just about four light-years away from our solar system might not be able to support life as previously suspected, according to research published in the Astrophysical Journal Letters.

The exoplanet, called Proxima b, orbits Proxima Centauri and was discovered last August.

New discoveries about Proxima b were made with the help of a computer model that simulated conditions on Proxima b based on observed data of the exoplanet with data about Earth as a substitute for data that couldn’t be collected on Proxima b. The finding was that any atmosphere the planet may have had likely burned up billions of years ago.

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While Proxima b is in the habitable zone, meaning not too far from its star and not too close, there are still a number of other factors that determine whether a planet it habitable. The presence of water is one of them and it’s not determined by the location in the habitable zone. Another factor to be determined is whether an atmosphere could survive around the planet.

Atmosphere’s provide temperature regulation as well as protection from the radiation in space and acts as a container that helps keep in the chemical building blocks for life, according to NASA.

The computer model used to determine whether Proxima b’s atmosphere would survive where it is substituted Earth’s atmosphere, magnetic fields and gravity for Proxima b’s as all of those factors are unknown. The planet has never been observed passing its host star, which is necessary for usual techniques used to determine such factors rendering those techniques useless to researchers. Data collected with NASA’s Chandra X-ray Observatory allowed researchers to measure the average amount of radiation Proxima Centauri gives off.

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Using all of this information the researchers were able to use the model to estimate how long it would take for Earth’s atmosphere, on Proxima b, to escape. They found that it could take as little as 100 million years for Earth’s atmosphere to disappear from Proxima b. The issue is that the planet’s been around for four billion years. Even when researchers assumed the lowest levels of escape, it all still escaped the planet within two billion years. So anything alive on the planet or any water it had would have been destroyed millions or billions of years ago.

So the chances that Proxima b would be able to support life are far slimmer than previously thought. “Things can get interesting if an exoplanet holds onto its atmosphere, but Proxima b’s atmospheric loss rates here are so high that habitability is implausible,” Jeremy Drake, a co-author on the study and astrophysicist at the Harvard-Smithsonian Center for Astrophysics told NASA.