India, March 11 -- While science fiction has terrified us with alien microbes infecting astronauts and threatening humanity, a new study published in Cell reveals a stunning twist: the real danger lurking aboard the International Space Station isn't an invasion of unknown alien pathogens, it's the absence of microbial allies we evolved with on Earth that might be weakening astronaut immune systems.

For 20 years, astronauts have orbited Earth in what is essentially a sealed bubble- a meticulously maintained environment where microbial diversity is drastically reduced. University of California San Diego researchers, led by microbiologist Rob Knight, have mapped this hidden world by analysing 803 surface samples from throughout the station....