It sounds like science fiction, but the theory of panspermia, in which life can naturally transfer between planets, is considered a serious hypothesis by planetary scientists. The suggestion that life did not originate on Earth but came from elsewhere in the universe (for instance, Mars), is one possible variant of panspermia. Planets and moons were heavily bombarded by meteorites when the Solar System was young, throwing lots of material back into space. Meteorites made of Mars rock are occasionally found on Earth to this day, so it is quite plausible that simple life forms like yeasts or bacteria could have been carried on them.
Yet serious questions remain for supporters of this theory. Would even the hardiest life forms be able to survive an impact which ejects the rock into space? Could they live through the freezing temperatures and deadly radiation of space? And could they enter the atmosphere and hit the surface of Earth without being killed?
New research presented at the European Planetary Science Congress at UCL aims to answer the final question, of whether entry and impact is survivable for simple organisms. Using frozen samples of Nannochloropsis oculata, a type of single-celled ocean-dwelling algae, Dina Pasini (University of Kent) set out to test the conditions which early life would have had to survive if it did indeed travel through space.
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