Too Much of a Good Thing? The Planets of TRAPPIST-1

In our consistent search for life outside of our planet, we have found some surprisingly good candidates. One thing scientists look for is water. As far as we know, water is essential to life. On NASA’s website they write, “Water is essential at the molecular level to moving life beyond its basic building blocks; thus, searches for extraterrestrial life usually involve a search for liquid water.” But too much water might also be a problem.

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Cue TRAPPIST-1, a planetary system 39 light years away from the solar system. The planets were discovered thanks to the transit method (in which a telescope watches a star for small dips in brightness. These dips can let scientists know if an exoplanet is passing in front of it). The star is roughly the same size as Jupiter and there are believed to be at least 7 planets in orbit. All the planets “transit their star, meaning that they pass in front of it.” Most of the planets appear to be about as big as Earth and Venus, and, thanks some clever scientists, we can also deduce that these planets receive an amount of light similar to many of our solar system. Most importantly, these planets are in the “habitable zone”, meaning that liquid water could exist on the surface.

The planets are rocky and, as a new study suggests, have a lot of water...maybe even too much water, according to researchers from School of Earth and Space Exploration at Arizona State University.

The planets are called B, C, D ,E, F, G, H and some of them contain surprising amount of water. For example, B and c are believed to have around 10% water by mass. However, the further out planets F and G are roughly 50% water. Now, I know what you’re going to say…”But Earth is 70% water!” and, well, you’re right in a way. Earth’s surface area is 70% water...but it only accounts for .2% of its mass.

Basically, these planets could be insanely wet. Extreme Tech puts it in plain terms, “The outer planets would have more than 1,000 times the volume of water we have on Earth.” And while water seems to be a necessity of life...too much water “could impede the development of life because there are certain chemical processes that occur on dry land. In addition, the pressure of all that water pressing down on the mantle could prevent most volcanic activity. Without the carbon dioxide from volcanic activity, even planets in the habitable zone could have fallen victim to a runaway snowball effect.”

Although originally seen as a great place to further explore the possibility of life, the TRAPPIST-1 seems to be a less successful investigation. In a study published by the researchers in the journal Nature Astronomy they note, “With no exposed land, key geochemical cycles including the drawdown of carbon and phosphorus into oceanic reservoirs from continental weathering will be muted, thus limiting the size of the biosphere," the researchers wrote in the new study, which was published online today (March 19) in the journal Nature Astronomy. "As such, although these planets may be habitable in the classical definition of the presence of surface water, any biosignature observed from this system may not be fully distinguishable from abiotic, purely geochemical sources.”

Ultimately, the excess of water has the power to potentially shut down some of the needed geological processes that allow life to get its bearing on the world.







The above image is liscensed under Attribution-ShareAlike 2.0 Generic (CC BY-SA 2.0) by Flickr User Driver Photographer.