Hubble Reveals TRAPPIST-1 Planets Might Have Water, But Are They Habitable?

Recent findings from the Hubble Space Telescope suggest that five of the TRAPPIST-1 planets hold water on them, but can they sustain life like many are hoping?

Late last year, a team of astronomers sought to determine the amount of ultraviolet radiation in each of the seven TRAPPIST-1 exoplanets using the Hubble Space Telescope to gather the data. As related by lead researcher Vincent Bourrier from the Observatoire de l’Université de Genève in Switzerland in a joint statement from NASA and the European Space Agency, this is a key step in determining whether planets could, or could not hold water.

“Ultraviolet radiation is an important factor in the atmospheric evolution of planets. As in our own atmosphere, where ultraviolet sunlight breaks molecules apart, ultraviolet starlight can break water vapor in the atmospheres of exoplanets into hydrogen and oxygen.”

Using Hubble’s Space Telescope Imaging Spectrograph instrument in September, November, and December 2016, the scientists theorized that six of the seven TRAPPIST-1 planets could have lost a lot of water throughout their history, according to Engadget. These six planets were the closest ones to their host star, and are believed to have lost the equivalent of 20 Earth oceans over time. On the other hand, the five outermost planets were cited as having at least a small chance of holding liquid water.

Engadget noted that TRAPPIST-1 planets E, F, and G, which are among the three farthest from their host star, are in the so-called “habitable zone,” or a region where Earth-like planets can hold liquid water and potentially support life. Based on their data, these exoplanets might have lost only about three Earth oceans’ worth of water each, making it possible that there is still some form of water on their surfaces. That might also be true for planets D and H, though the researchers stressed that the possible amount of water depends on the age of the solar system, as well as the amount of water each planet formed with.

Although water is a key ingredient required for a planet to sustain some form of life, there are some limitations to the new research, according to Seeker. The scientists weren’t able to detect signs of hydrogen surrounding the planets, though they remain hopeful that further studies could confirm the presence of the element. And while most of the TRAPPIST-1 planets could hold water, Engadget added that there’s also a good chance that radiation may have destroyed the planets’ atmospheres, potentially making them inhabitable all along.

Still, the researchers aren’t giving up hope, and believe that their new research is a good sign that there might be TRAPPIST-1 exoplanets that are habitable. But study co-author Julien de Wit from the Massachusetts Institute of Technology stressed that more data needs to be gathered, and that actual proof is needed of the TRAPPIST-1 planets possibly having some water remaining.

“This concludes that a few of these outer planets could have been able to hold onto some water, if they accumulated enough during their formation. But we need to gather more information and actually see a hint of water, which we haven’t found yet.”

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