Past asteroid impacts may have done significant damage to life on Earth, but a new study suggests that a ‘Goldilocks’ impact from a space rock might be an important ingredient in supporting life on other planets.
The research, which has not been published in a scientific journal but can be read on the arXiv repository, points out that when a space object such as an asteroid or comet hits the planet, two events happen: the material from the object is added to the exoplanet’s mass and some of the atmosphere from the surrounding area goes into space.
“Given sufficient bombardment, planets below the gap would be expected to lose their atmospheres, while those above could have atmospheres enhanced in volatiles,” the study’s abstract states. “The level of atmosphere alteration depends on the total bombardment a planet experiences, and so on the system’s (usually unknown) other planets and planetesimals, though massive distant planets would have low accretion efficiency.”
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The abstract continues: “Habitable zone planets around lower luminosity stars are more susceptible to atmosphere stripping, disfavouring M stars as hosts of life-bearing planets if Earth-like bombardment is conducive to the development of life.”
In an interview with Live Science, the study’s lead author, Mark Wyatt, said large impacts could hurt the chance for a planet to be able to support life, but a smaller one could aid with conditions for supporting life, adding so-called “volatiles” (such as water and carbon dioxide) to their atmosphere.
The researchers noted that the ‘Goldilocks’ size for an asteroid would be between 60-feet wide and 3,300-feet. Anything larger than that, approximately 1 to 12 miles, would strip the atmospheres more than is needed.
Previous studies have suggested that our moon was formed roughly 4.5 billion years ago from an asteroid colliding with Earth when it was still forming.
Asteroids in our solar system routinely carry water on them. A recent study suggested that the second interstellar object discovered, Comet 2I/Borisov, could be carrying water on it from beyond the solar system.
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One category of celestial objects that may not be so lucky, however, is M class stars, likely due to the number of habitable exoplanets that have already been discovered, according to the study.
“Habitable zone planets around lower luminosity stars are more susceptible to atmosphere stripping, disfavouring M stars as hosts of life-bearing planets if Earth-like bombardment is conducive to the development of life,” the abstract added.
“For M stars, their low luminosity means that the habitable zone is much closer to the star than for a star like the sun,” Wyatt added in his interview with Live Science.