We’ve all seen sci-fi movies and read books where it’s revealed that visitors from another world were responsible for sparking life on Earth. But, would they theoretically have been able to spread life to our world even if they weren’t alive? Or put another way, if an Earth astronaut died in space, and his body eventually ended up on some lifeless planet without first burning up in its atmosphere, could it then seed life across that previously lifeless world.
It’s easy to imagine a number of scenarios in which a human body could end on a distant planet in the future. For instance, a person could accidentally become separated from a ship during a space walk and die in space; or a space ship could crash-land; or maybe space burial becomes the preferred way to dispose of bodies in the future. No matter what story you wish to imagine, it is at least possible for a deceased corpse to spread life to another planet, but in order for such an amazing event to occur a number of factors would have to align first, according to Gary King, professor of biological sciences at Louisiana State University:
1. Needs to Be in a Capsule
Bacteria and other micro organisms in the body are able to live in harsh conditions and can survive long after its host has perished. It’s theoretically possible that a body could reach the surface of a planet with living bacteria still in residence that then moves to the planet and begins to colonize. In order for this to occur, though, scientists say that the body would need to be in some type of container as a body just floating in a spacesuit would be subjected to too much heat going through an atmosphere for any bacteria to survive.
2. Needs to Be Ideally Stored
For bacteria to remain viable, the vessel that is carrying the corpse would need to have the right conditions inside. Some scientists say that the temperature would ideally need to be above freezing, although others speculate that if the temperatures were low enough to potentially freeze dry the body and the bacteria with it, it would be possible for microorganisms to survive and then become rehydrated back on the planet’s surface.
3. A Minimal Amount of Time in Space
The longer the body drifts through space, the less likely it would be that any bacteria would survive, as the intense radiation that is constantly moving through the universe would cause mutations to its bacterial RNA and DNA over time. Scientists state, for instance, that a trip from Earth to Mars could be short enough for bacteria to survive, but likewise believe that the same corpse that somehow found its way from Earth to Proxima Centauri would be unlikely to have any viable microorganisms living inside it.
Finally, some biologists believe that even without any living bacteria, it’s theoretically possible for a human body to jump-start the development of life by passing on key compounds like DNA and amino acids. However, enough cells would still need to survive the trip through space, and the subsequent crash landing on the planet. Furthermore, the process of starting new life would be more likely if a corpse(s) landed in a shallow pool where their chemicals could stay together, rather than in an ocean where they would soon become diluted.