Space dust may contain traces of extraterrestrial life.

 

Image: Pixabay

Understanding the history of life on Earth and its origins requires the search for extrasolar biosignatures. Such signatures may be discovered through astronomical observations of exoplanets, but it is challenging and impossible to assert that exoplanet atmosphere remote sensing has reliably detected life.

In a recent research, Professor Tomonori Totani of the Department of Astronomy at the University of Tokyo suggested an alternative strategy: space dust may hold direct or indirect signs of life from the hosting world, such as microorganism fossils.

"I suggest we look for possible signs of life in well-preserved grains ejected from other worlds," Prof. Totani said. The typical approach to finding extraterrestrial life involves looking for communication, which would suggest intelligent life but rule out any pre-technological life. Alternatively, scientists may be looking for atmospheric traces of life, but even in the absence of direct evidence, there may be another reason. However, if there are indications of life in dust particles, we could not only be certain but also quickly learn the answer.

The basic premise is that large asteroid collisions can send material from Earth into space. It's possible that some of the rocky material in this ejecta contains recently extinct or possibly fossilised microorganisms. Different-sized bits will behave differently in space because this material will come in a broad range of sizes. Some of the more substantial pieces might re-fall or enter a steady orbit around a neighbouring planet or star.

Space dust. This piece of interplanetary dust is thought to be part of the early solar system and was found in our atmosphere, demonstrating lightweight particles could survive atmospheric entry as they do not generate much heat from friction. ©2023 NASA CC-0

In addition, some fragments that are much smaller might be too tiny to contain any life that can be seen. Nevertheless, particles as tiny as 1 micrometre (one-millionth of a millimetre) could not only contain a single-celled organism specimen, but they might also leave their home solar system and, under the right conditions, even journey to other solar systems.

 

"My paper discovers this idea using the data that is presently available on the numerous features of this state," said Totani. The chances that any ejecta carrying life signs from another world could even reach us are greatly diminished by the lengthy travel times and vast distances involved. The odds are even lower when you consider the number of phenomena in space that have the potential to melt or irradiate small objects.

"However, I estimate that roughly 100,000 such granules could arrive on Earth each year. This estimate may be too high or too low due to the numerous unknowns involved, but it is still beneficial to investigate because the tools are already in place to do so.

 

Such granules might already exist in large quantities on Earth. Space dust could be recovered fairly readily, but it remains difficult to distinguish extrasolar material from material that comes from our solar system. However, there are already projects that use aerogels, which are extremely light materials, to collect dust in space.

Totani stated, "I hope that researchers from various fields will be intrigued by this concept and begin to thoroughly examine the viability of this new search for extrasolar life."

Reference: techexplorist.com