Life Might Jump Between Planets In The TRAPPIST-1 System

Arist's impression of TRAPPIST-1. NASA, ESA, and G. Bacon (STScI)

A new study has further cemented the idea that TRAPPIST-1 might be our best bet for finding life outside the Solar System.

One of the most interesting things about this seven-planet system, about 40 light-years from us, is that the planets are all in very tight orbits around their star. They are as little as 600,000 kilometers (380,000 miles) from each other – less than twice the distance from Earth to the Moon.

Three of the planets in the system are in the star’s habitable zone, where liquid water and even life could exist. And Harvard University scientists Manasvi Lingam and Avi Loeb say microbial life could actually be transferred between these planets. Their study is available on arXiv.

“Because these distances are so close, a lot more different kinds of species, microbial or otherwise, could migrate from one planet to another,” Lingam told New Scientist.

The idea is based around something called panspermia. This is the theory that life can be transferred between worlds via a number of methods, including a meteorite impacting the surface and sending life-harboring debris into space.

Some have proposed that, in our own Solar System, this process may have transferred life from Mars to Earth. But panspermia is hotly contested, and we don’t really have good evidence that it occurs yet.

The TRAPPIST-1 planets are relatively close to each other. NASA/JPL-Caltech

Nonetheless, Loeb and Lingam suggest that if it does happen, and just one of TRAPPIST-1’s habitable planets formed life, then it’s possible that the other two have life too.

“If panspermia (or pseudo-panspermia) is an effective mechanism, it leads to a significant boost in the probability of abiogenesis [the spontaneous appearance of life],” the researchers write in their paper.

We don’t know if the system is habitable yet, however. One issue is that the star these planets orbit is an ultra-cool dwarf, which is thought to unleash powerful bursts of radiation as flares. With the planets being so close to the star (20 to 100 times closer than Earth is to the Sun), this could be detrimental to their chances of life.

It will depend on the age of the star, and whether the planets have always been in their current position or if they migrated inwards from further out, which is possible. In their study, though, Loeb and Lingam said we could “roll the dice three times” in this system compared to our own, reported Gizmodo, owing to the panspermia idea.

There’s going to be plenty more speculation about TRAPPIST-1, but we probably won’t know if the planets are habitable for sure until the James Webb Space Telescope (JWST) studies their atmospheres in the next few years. Until then, who knows – maybe TRAPPIST-1inians relax by going on short jaunts to their neighboring planets.

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