TRAPPIST-1 Planets' Water Could Ruin Chances of Finding Aliens

Astrobiologists looking for life beyond Earth will usually tell you that finding water is a good sign. But in the case of the TRAPPIST-1 system just 40 light-years away, the planets might actually be too full of water to sustain life.

A new study published in Nature Astronomy finds that the planets in this system are very likely full of water, to the point where it’s detrimental to harboring potential life. After various calculations, the team on the study found that the eight known TRAPPIST-1 planets have unusually low densities for their masses, which can only be explained by the fact that they contain a lot of water or ice. This actually diminishes odds of finding life on these planets.

“We typically think having liquid water on a planet as a way to start life, since life, as we know it on Earth, is composed mostly of water and requires it to live,” the study’s co-author Natalie Hinkel of Vanderbilt University explains in a press release. “However, a planet that is a water world, or one that doesn’t have any surface above the water, does not have the important geochemical or elemental cycles that are absolutely necessary for life.”

The TRAPPIST-1 planets.


Using a software called ExoPlex, researchers found that the TRAPPIST-1 planets closer to their ultracool dwarf star (planets “b” and “c” in this case) had less than 15 percent water by mass, which is still much more than here on Earth, which has 0.02 percent water by mass. It gets even more watery the farther from the sun you travel — outer planets like “f” and “g” had more than 50 percent water by mass, which is an almost unfathomable amount of water. They’re literally water worlds, hopefully without the other terrible features of that Kevin Costner movie.

After so much hype about TRAPPIST-1, it might be time to accept that we’re probably not going to find life there. Maybe next-generation telescopes like James Webb will get a closer look into the atmospheres of these weird worlds. Who knows? Maybe life on TRAPPIST-1 is just super well-adapted to Kevin Costner’s Waterworld.

Fingers crossed for space narwhals.

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