Written by Sama Labib

Friday, March 24, 2023 at 04:00 AM

When a large asteroid collides with a planet, the impact can cause cosmic changes—just ask the dinosaurs. (Or no, it died because of a space rock that hit Earth 66 million years ago.) These cataclysmic collisions can create craters the size of hemispheres and spread debris across entire planets and into interstellar space, Space.com reports.

In a new paper published online in the International Journal of Astrobiology, Totani argues that space debris ejected by a large enough impact on a habitable planet could carry evidence of that life into space.

Theoretically, fossilized microbes or other signs of life could be preserved in planetary ejecta, far from their home planet, awaiting their survival in the harsh environment of space. Other planets it harbors Earth-like life, where it can establish a foothold—or, perhaps, probe for evidence of alien existence.

In some ways this idea is similar to the panspermia hypothesis, which holds that life is ubiquitous and spreads from one planetary body to another throughout the galaxy.

Totani cites this at the beginning of his thesis, along with the observation that Martian meteorites have been found on Earth. “My paper explores this idea using available data on various aspects of this situation,” Totani said.

And not all debris can be ejected from an exoplanet fast enough to escape not only its planet’s gravity, but also the planet’s host star; Rather, escapees should be tiny, and the fragments would be about a micrometer (thousandths of a millimeter) large enough to host something like a single-celled organism, Totani calculates, and small enough to reach interstellar speeds.