Hitchhiking Microbes
With every launch, spacecraft carrying humans into space bring along a few uninvited guests.

Humans are home to trillions of microbes: bacteria, fungi, archaea, and protozoa to name a few. They colonize our skin, gut, and numerous organs in between, helping us digest food and regulate our immune systems. While we might want to avoid bringing microbes into space, we can’t exactly help it.
“Wherever we go, we shed our microbes,” said Kasthuri Venkateswaran, an astrobiologist at NASA Jet Propulsion Laboratory. “It is part and parcel of life.”
Scientists and engineers do their best to reduce the numbers of microbes travelling into space by requiring astronauts to quarantine prior to launch and by implementing rigorous cleaning procedures for everything onboard. But there’s no way to get rid of all of the microbes on and in the human body.
From cozying up to electrical cables, eating away at windows, to floating on dust particles, microorganisms have made their homes in some unexpected places in space.