The alien microbes are supposed to be discovered when spacecraft return to Earth, not before they've left, right? Not according to a new study of several NASA clean rooms—the supposedly sterile environments in which engineers assemble and test the components of various spacecraft before launch.

By sampling the air and surfaces in clean rooms at the Jet Propulsion Lab, Johnson Space Center and Kennedy Space Flight Center, scientists uncovered nearly 100 types of bacteria. And about 45% of them are believed to be novel. The study should help scientists improve the clean room environment, which will in turn reduce the risk of interplanetary spacecraft dropping our organisms on far-off worlds.—Gregory Mone

Via NY Times