Space dust may contain signs of extraterrestrial life

After massive collisions, such as asteroid impacts, some materials from impacted planets may be ejected into space and travel vast distances for extremely long periods of time. According to a new study led by the University of Tokyo, this material could contain direct or indirect signs of life from the planet of origin, such as fossils of microorganisms, that could potentially be detected by astronomers in search of extraterrestrial life. 

Although space dust can be an annoyance to some astronomers since it may hinder their observations of distant objects, it could also be a useful tool for learning about something distant without needing to leave the safety of our own planet.

“I propose we study well-preserved grains ejected from other worlds for potential signs of life,” said study author Tomonori Totani, a professor of Astrophysics at Tokyo. “The search for life outside our solar system typically means a search for signs of communication, which would indicate intelligent life but precludes any pre-technological life. Or the search is for atmospheric signatures that might hint at life, but without direct confirmation there could always be an explanation that does not require life. However, if there are signs of life in dust grains, not only could we be certain, but we could also find out soon.”

According to Professor Totani, after large asteroid collisions eject ground material into space, recently deceased or fossilized microorganisms may be contained in some of this material. While some larger pieces might fall back down or enter permanent orbits around local planets or stars, and some pieces may be too small to contain any traces of life, dust grains with a dimension of roughly one micrometer (one-thousandth of a millimeter) might not only host single-celled organisms, but they could also escape their solar system and – under the right circumstances – even reach ours.

In fact, such grains may have already reached the Earth in plentiful amounts and lie hidden in Antarctic ice or under the seafloor. While these materials could be retrieved relatively easy, analyzing them for signs of life remains a complex matter, requiring interdisciplinary collaboration between scientists. However, if this investigation is extended into space, there are already missions which capture dust in the vacuum by using ultralight materials known as aerogels.

“My paper explores this idea using available data on the different aspects of this scenario. The distances and times involved can be vast, and both reduce the chance any ejecta containing life signs from another world could even reach us. Add to that the number of phenomena in space that can destroy small objects due to heat or radiation, and the chances get even lower,” Totani said. 

“Despite that, I calculate around 100,000 such grains could be landing on Earth every year. Given there are many unknowns involved, this estimate could be too high or too low, but the means to explore it already exist so it seems like a worthwhile pursuit. I hope that researchers in different fields are interested in this idea and start to examine the feasibility of this new search for extrasolar life in more detail,” he concluded.

The study is published in the International Journal of Astrobiology.

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By Andrei Ionescu, Earth.com Staff Writer

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