Lithopanspermia - you can add this word to your astronomical dictionary. But what does it mean? It means the spread of living organisms from within Earth rocks that fly off into outer space after large meteorological collisions take place. In this sense, it is these forms of terrestrial life that would be considered the so-called "alien invaders" from sci-fi.
In a new study, scientists are studying the probability of an explosion on Earth's crust, caused by asteroids throughout the past 3.5 billion years, to have spread the seeds of life to other planets in our solar system.
As you might guess from the name, lithopanspermia is a variation of panspermia, which is a hypothesis that life spreads from one planetary body to another after cataclysmic events occur.
A resistant bacteria that has evolved on Planet A is ejected into space, trapped in a piece of rock. If it has a good enough shield and the potential to survive in extreme conditions, it is highly possible for it to reach Planet B via meteorite, carrying with it the potential to multiply in the new location.
The best part is that we already know that this transportation mechanism or panspermia exists - for example, rocks from Mars have been found as meteorites on Earth. So it is not at all surprising that biological material can also be transported by these processes.
And the more scientists discover that some bacteria (rightfully called extremophiles) can exist in extreme environments, the more realistic the hypothesis of panspermia sounds.
Naturally these assumptions stir many philosophical discussions among astrobiologists. Up until recently, the discussion was that life came from space and seeded it on Earth billions of years ago through meteorites.
Now the opposite is being discussed - could life from our own planet have been delivered by courier-meteorite to other regions in the solar system, such as Mars or even Europa?