According to a study authored by Tomonori Totani, professor of astronomy at the University of Tokyo, up to 100,000 life-bearing dust particles hit Earth every year.
When a large asteroid hits a planet, the impact can have cosmic consequences – ask the dinosaurs. (Or don’t ask; they became extinct, destroyed by a space rock that fell to Earth 66 million years ago).
These cataclysmic collisions can create hemisphere-sized craters and scatter debris across the planet and into interstellar space.
Totani argues that debris thrown into space by a violent enough collision with a planet inhabited by life could carry evidence of that life into space.
Theoretically, fossilized microorganisms or other signs of life could be preserved in planetary ejecta as they move away from their home planet, persisting in the harsh environment of space.
Some of this debris could end up on the surface of other habitable planets, such as Earth, where it could take root – or possibly be studied for the presence of alien life.
This idea is somewhat similar to the panspermia hypothesis, which suggests that life is omnipresent and spreads throughout the galaxy from one planetary body to another.
Totani refers to this early in his work, along with the observation that Mars meteorites have been found here on Earth.
“My paper explores this idea using available data on various aspects of this scenario,” Totani said in a press release.
Not all exoplanet debris can be thrown out at such a speed that they escape the gravity of not only their planet, but also the host star; rather, the debris must be tiny.
Totani calculated that the fragments, about one micrometer (one thousandth of a millimeter) wide, would be large enough to contain something like a single-celled organism, and small enough to reach interstellar speeds.
“Distances and time can be enormous, and both of these factors reduce the likelihood that an ejecta containing signs of life on another world will reach us at all,” Totani said.
“Add to that the number of phenomena in space that could destroy small objects due to heat or radiation, and the chances become even smaller.”
However, against all odds, Totani’s calculations show that up to 100,000 of these pieces of cosmic dust could fall on Earth each year, which may be present and well preserved in the Antarctic ice or on the seabed.
These samples may be relatively easy to extract, compared to space dust containing evidence of microbial life still floating around in space. But the last scenario is not impossible either.
“Distinguishing extrasolar material from material produced in our own solar system is still a challenge,” the press release said, but noted that airgel technologies that capture space dust already exist today.
At the end of the article and press release, Totani calls on scientists from related fields to take up this research and explore the possibilities it could add to the search for life outside our solar system.
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