Japanese astronomer Tomonori Totani from the University of Tokyo proposed a novel idea to expand on the existing range of methods to search for extraterrestrial life focusing on space dust that finds its way to Earth, expelled from other solar systems.
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After significant collisions, such as those caused by asteroid impacts, a portion of an affected planet's material can be expelled into outer space. If the planet has life, the expelled material could contain subtle indications of life, such as microorganism fossils. Humans could detect such indicators in the near future using contemporary technology.
Professor Totani wrote a paper on this concept, proposing that we examine well-preserved grains ejected from other worlds. Currently, there exists a problem with our methods of detecting 'pre-technological life.'
We focus on atmospheric signatures that might hint at life, but without direct confirmation, it is always possible to find an explanation that does not require life. However, according to professor Totani, signs of life in dust grains could bring much more certainty.
Extraterrestrial particles finding their way to Earth
The fundamental concept behind Totani's idea is that sizeable asteroid impacts can expel ground material into space, which may potentially contain dead or even fossilized microorganisms.
Ejected material commonly exhibits a wide range of sizes, and its behavior in space varies accordingly. The problem with larger pieces is that they commonly either reenter the planet's atmosphere or enter stable orbits around a nearby star or planet, meaning they will probably stay in their home solar system. The very smallest pieces, on the other hand, may not contain any verifiable signs of life.
However, particles of an in-between size (grains that are approximately 1 micrometer in size) can contain not only a single-celled organism but could also escape their original solar system and potentially journey to our solar system under favorable circumstances.
Thid interplanetary dust particle is believed to originate from the early solar system and was recovered from our atmosphere. This discovery suggests that small, lightweight particles can survive atmospheric entry since they generate minimal heat from friction.
(Image Credit: NASA)
Totani: "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 continues: "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."
Some particles may have already landed on Earth
Abundant quantities of the above-mentioned minute grains may already exist on Earth, conserved in areas like the Antarctic ice or the seafloor.
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The recovery of space dust from these areas is achievable with contemporary technology. However, distinguishing between the extrasolar matter and material originating from our solar system will be challenging.
Exploration can be extended beyond Earth; existing missions employ ultralight materials known as aerogels to trap dust in the vacuum of space.
Totani: "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."
If you are interested in Totani's work, be sure to check out the paper published in the peer-reviewed International Journal of Astrobiology listed below.
Sources and further reading:
Solid grains ejected from terrestrial exoplanets as a probe of the abundance of life in the Milky Way - International Journal of Astrobiology. - (DOI: 10.48550/arXiv.2210.07084)
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