National Geographic reports: Living bacteria have been found on the outside of the International Space Station, a Russian cosmonaut told the state news agency TASS this week.

Anton Shkaplerov, who will lead Russia’s ISS crew in December, said that previous cosmonauts swabbed the station’s Russian segment during spacewalks and sent the samples back to Earth. The samples came from places on the station that had accumulated fuel waste, as well as other obscure nooks and crannies. Their tests showed that the swabs held types of bacteria that were not on the module when it originally launched into orbit, Shkaplerov says.

In his interview with TASS, Shkaplerov says the bacteria “have come from outer space and settled along the external surface”—a claim that sparked some media outlets to issue frenzied reports about aliens colonizing the space station.

For now, though, details about the swabbing experiment are thin on the ground. Shkaplerov did not note whether the study has been vetted by a peer-reviewed journal, which means it’s unclear exactly when and how the full experiment was conducted, or how the team avoided any contamination from much more mundane bacteria on the cosmonauts or in the Earth-bound lab. Interview requests with the Russian space agency were unanswered when this article went to press.

Rather than microbes raining down from outer space, it’s much more plausible that the outside of the space station became contaminated by earthly organisms, many of which can survive in the harsh environment in orbit. [Continue reading…]

Indeed, the journey along Occam’s Razor is much shorter and vastly easier than any voyage from distant worlds.