A special microbe – called SAFR-032 – only shows up in NASA's ultra clean rooms. In space, its spores have a unique survival tactic, building up layers of cells to use as shields that in turn protect their DNA. When these tiny survivors return from orbit, they show greater resistance to antibiotics. In other words: space makes them stronger. This is a particular problem for NASA and its Outer Space Treaty, which forbids space agencies from interfering with the integrity of other planetary bodies in the solar system. In other words, transporting viable microbes from Earth to places like Mars is off-limits.