In 2002, several scientists claimed that bacteria high in Earth’s atmosphere came from space.
Last year, scientists said that bacteria in the upper atmosphere may actually make rain. Specifically, they said that bacteria can freeze at fairly warm temperatures, so that the “biological ice nuclei” form condensation nuclei which triggers rain.
Indeed, some scientists have speculated that bacteria cause rain as a means of transportation, so that they will “rain out” from the upper atmosphere to the surface of a planet.
Now, scientists have discovered a “hibernating” bacteria in a salt mine in Utah which they believe has been in suspended animation for 250 million years. There is evidence that this ability to hibernate for long periods of time is also useful for travel through space by the bacteria:
Bacteria have the ability to go into a kind of semi-permanent hibernation, but survival for this long was unheard of. After lying dormant in the salt crystal for 250 million years, the scientists added fresh nutrients and a new salt solution, and the ancient bacteria “re-animated.”
Dr. Russell Vreeland, one of the biologists who found the bacteria, pointed out that bacteria can survive the forces [of] acceleration via rubble thrown into space via a meteor impact. If it is possible for a bacteria to survive being [thrown] off the planet and to stay alive within a salt chunk for 250 million years, then in a sort of “reverse-exogenesis” it may be possible that earth’s own microbes are already out there.
Indeed, there is a more down-to-earth analogy to the idea of spacefaring bacteria: the humble coconut. Coconuts can float across long distances of water in the ocean, and when they land on a hospitable island, start growing.