Extraterrestrial life enthusiasts were thrilled last February when NASA announced the discovery of a new solar system, known as Trappist-1, composed of seven planets orbiting a star, with three of the planets lying within the so-called habitable zone — or just the right distance from their star for liquid water to exist on their surfaces.
Now, a new study from Harvard University raises the possibility that these three ‘Goldilocks’ planets are so close to each other, alien life could be catching rides from one planet to another — on rocks.
“The rocks are driven into space,” says co-author and Harvard astronomer Avi Loeb, in an interview with Gizmodo. “If there is life on one of them, life may be preserved inside these rocks and be transferred to another planet.”
Some scientists cite this process of transferring life from one planet to another by meteorite or comet, called ‘panspermia,’ as a possible explanation of how life on Earth began.
The proximity of the three Trappist-1 exoplanets suggests that some microorganisms would be able to survive the harsh conditions of space. Hitching a ride between the habitable planets would be some 1,000 times faster than between Mars and Earth, the authors say, as reported by Gizmodo.
Loeb and his co-author Manasvi Lingam tested their theory by creating models mimicking the patterns of certain island-hopping species on Earth.
“These planets are similar to islands on the surface of the Earth, and there are studies of the immigration of species from one island to another,” Loeb says. “We used the same model to illustrate that the likelihood is very high for transfer of life.”
All the excitement may be for nought if it turns out the Trappist-1 planets lack an atmosphere. Finding out is the next step, the researchers say.
Not all scientists find the Harvard scientists’ island-hopping metaphor particularly useful, however.
“This work is interesting, but no, planets are not islands, even if they are close,” said Valeria Souza from the National Autonomous University of Mexico, in a report by New Scientist.
The study is published in Earth and Planetary Astrophysics.