Recently discovered solar system could seed life between adjacent exoplanets

April 27, 2017 by Greg Borzo, University of Chicago
Illustration shows what each of the TRAPPIST-1 planets may look like, based on available data about their sizes, masses and orbital distances. Credit: NASA/JPL-Caltech

After NASA announced in February the discovery of a solar system with seven planets—three of which were deemed potentially habitable—UChicago postdoctoral scholar Sebastiaan Krijt began wondering: If a life form existed on one of these planets, could space debris carry it to another?

In research recently published in Astrophysical Journal Letters, Krijt and fellow UChicago scientists conclude that forms, such as bacteria or single-cell organisms, could travel through the newly discovered TRAPPIST-1—an unusual solar system that presents an exciting new place in the Milky Way to search for extraterrestrial life.

"Frequent material exchange between adjacent planets in the tightly packed TRAPPIST-1 system appears likely," said Krijt, the study's lead author. "If any of those materials contained life, it's possible they could inoculate another planet with life."

For this to happen, an asteroid or comet would have to hit one of the planets, launching debris into space large enough to insulate the from the hazards of space travel. The material would have to be ejected fast enough to break away from the planet's gravitational pull but not so fast that it would destroy the life form. And the journey would have to be relatively short so the life form could survive.

The researchers ran several simulations for TRAPPIST-1 and found that the process could occur over a period as short as 10 years. Most of the mass transferred between planets that would be large enough for life to endure irradiation during transfer and heat during re-entry would be ejected just above escape velocity, they concluded.

Illustration shows the possible surface of TRAPPIST-1f, one of the seven recently discovered Earth-sized exoplanets. Credit: NASA/JPL-Caltech

"Given that tightly packed planetary systems are being detected more frequently, this research will make us rethink what we expect to find in terms of and the transfer of life—not only in the TRAPPIST-1 system, but elsewhere," said Fred Ciesla, UChicago professor of geophysical sciences and a co-author of the paper. "We should be thinking in terms of systems of planets as a whole, and how they interact, rather than in terms of individual ."

Number of discovered exoplanets exploding

The first exoplanet, a planet orbiting a star other than the sun, was confirmed in 1992. Today, more than 3,600 exoplanet candidates have been discovered, with at least 3,000 additional candidates waiting to be confirmed. In addition, more than 600 multiple exoplanetary systems have been confirmed.

"The relatively new field of exoplanetology is exploding and being considered more seriously than ever," Ciesla said. "If we took the solar system as a model, we could never have imagined the things we're finding, such as the recent discovery of a planet that orbits two suns."

The push now is not so much to discover new exoplanets but rather to characterize them, determine how they evolved and understand how they interact, Krijt said.

Exoplanetary systems serve as laboratories to help scientists comprehend the solar system, Ciesla said, noting that 40,000 tons of space debris falls to Earth each year. "Material from Earth must be floating around out there, too, and it's conceivable that some of it might be carrying life. Some forms of life are very robust and could survive ."

Explore further: Temperate earth-sized worlds found in extraordinarily rich planetary system (Update)

More information: Fast Litho-panspermia in the Habitable Zone of the TRAPPIST-1 System. Astrophysical Journal Letters, Volume 839, Number 2. DOI: 10.3847/2041-8213/aa6b9f

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not rated yet Apr 27, 2017
Isn't this just the panspermia hypothesis that's been around for decades? It's cool and all, but I fail to see how this is novel research.
5 / 5 (1) Apr 27, 2017
Why it is novel is that the transfer of life could be done over a short range like this just with the life forms that we have on earth now. The Tardigrade, or Water Bear, is able to go into a spore like form that we have tested and survives not only the vacuum but radiation conditions of LEO and could, for the short distances and times considered, survive being transported in this manner in such a spore like form. And that is a rather high form of life, considering. Simpler forms such as bacteria or algae may survive even easier.

Panspermia is the idea of crossing lightyears for life, this system entails orbits smaller than that of Mercury so it rather defines a smaller area and we have now actually found a system where this COULD work, rather than just being totally thought games.
5 / 5 (3) Apr 28, 2017
Isn't this just the panspermia hypothesis that's been around for decades?

Panspermia has the problem that it has not been shown that life can survive for the length of time it would take to get from one system to the next (consider that something travelling reasonably fast - like the voyager probes - will take more than 300k years before coming even close to another solar system).
not rated yet Apr 28, 2017
I stand corrected. I was thinking of the theory that Mars could've seeded early Earth, but you are correct as "panspermia" refers to transfer between star systems.

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