To build a spacecraft, you need an extremely clean construction zone. That’s essential if you’re sending a robot to another world to search for signs of microscopic alien life. One wouldn’t want to mistake a stowaway for the first evidence of extraterrestrials. It’s also vital if you want to protect humans from potentially dangerous microbes on long-term trips to space—up to the International Space Station, to the Moon, or to Mars.

That’s why spacecraft are often built in clean rooms, some of the most sterile environments on Earth. But a decade ago, scientists were shocked to discover a brand-new type of bacteria had invaded not just one spacecraft clean room, but two—thousands of miles apart.

That bacterium, Tersicoccus phoenicis , turned out to be harmless. But it was a cause for c

See Full Page