In an interview Monday, Russian cosmonaut Anton Shkaplerov reported bacteria had been found on the outside of the International Space Station (ISS) — and it hadn't been there when the ISS modules launched. Instead, the microorganisms swabbed from the cracks and crevices of the space station had come from outer space, he said.
But, but, but: The details of the analysis are so far thin. And, in a previous mission, bacteria from Earth made it to the space station via a tablet, supporting the possibility of contamination this time, too. Recent research also seems to indicate microbes can get kicked high above Earth in space dust and by other space weather events, which offers another very plausible reason for how bacteria wound up on the ISS hull.
The bottom line: The bacteria probably came from Earth itself. "Microbes are still partying at 9 miles up and have been found as high as 47 miles above the surface," Mary Griggs wrote in Popular Science.