In the search for alien life, one Japanese scientist believes that we should be looking closer to home – at space dust, specifically.
While searching for signs of life in tiny rocks ejected from other worlds sounds like science fiction, it could warrant serious consideration.
Following enormous collisions, such as asteroid impacts, some amount of material from an impacted world may be ejected into space.
This material can travel vast distances and for extremely long periods of time. In theory, this material could contain direct or indirect signs of life from the host world, such as fossils of microorganisms.
Professor Tomonori Totani from the University of Tokyo believes that dust could be a useful tool to help astronomers learn about something distant without having 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 Totani. ‘If there are signs of life in dust grains, not only could we be certain, but we could also find out soon,’
The basic idea is that large asteroid strikes can eject ground material into space. There is a chance that recently deceased or even fossilized microorganisms could be contained in some rocky material in this ejecta.
This material will vary in size greatly, with different-sized pieces behaving differently once in space. Some larger pieces might fall back down or enter permanent orbits around a local planet or star.
Some much smaller pieces might be too small to contain any verifiable signs of life but grains in the region of 1 micrometre (one-thousandth of a millimetre) could not only host a specimen of a single-celled organism, but they could also potentially escape their host solar system altogether, and under the right circumstances, maybe even venture to ours.
Totani’s paper published in the International Journal of Astrobiology explores this idea using available data.
Still, that the chances of space dust containing signs of life reaching us have several barriers like heat and radiation.
Despite that, Totani calculates around 100,000 such grains could be landing on Earth every year.
‘There may be such grains already on Earth, and in plentiful amounts, preserved in places such as the Antarctic ice, or under the seafloor,’ said Totani.
While retrieving the space dust from these places could be relatively easy, distinguishing them from material originating in our own solar system is still a complex matter.
Totani pointed out that if the search was extended to space itself, there were already missions that capture dust in the vacuum using ultralight materials called aerogels.
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