Tomonori Totani, an astrobiologist at the University of Tokyo, proposes expanding the search for life beyond Earth to cosmic dust research. In an article published in the journal International Journal of Astrobiology, suggests that cosmic dust may contain signs of life transported from other planets by asteroid impacts.

Despite many years of efforts by researchers, no evidence of the existence of life outside Earth has been found. There are two possible reasons for this; First, there is no other life to be found. Second, because of the great distances, we don’t have the technology to find it. Totani states that part of the problem is the difficulty of studying exoplanets millions of miles away. Therefore, he proposes an alternative approach – the study of cosmic dust falling to Earth. He notes that such dust can be found in ice fields around the poles or perhaps in the atmosphere.

Totani states that asteroids slammed into planets in the Milky Way galaxy and hurled debris each time they hit. In larger impacts, some of this debris can be ejected with such force that it escapes the planet’s gravitational field and flies into space. And if there is life on that planet, some of that evidence could be thrown away as a piece of cosmic dust with it.

Totani suggests that the optimal size of cosmic dust particles is about 1 micrometer; such tiny particles would be large enough to contain evidence of life, but small enough to escape the gravity of their home planet and star. They will also be able to travel fast enough to reach distant planets such as Earth. He estimated that about 100,000 of this species crash into the Earth each year. He suggests that such grains may contain traces of life originating from other worlds and can be analyzed for biosignatures. It also states in the press release that there is evidence that space debris from Mars has landed on Earth.