The International Space Station (ISS) photographed soon after the space shuttle Atlantis and the station began their post-undocking relative separation. Undocking of the two spacecraft occurred at 3:53 am (CST) on Nov. 25, 2009. NASA

"Bacteria… From the outside… Oooooo." Russian cosmonauts have discovered bacteria living on the outside of the International Space Station (ISS). Since the bacteria were not on the exterior hull when the habitable satellite was launched back in 1998, this is particularly odd.

Samples from the hull of the ISS were taken with cotton swabs during a spacewalk by the Russian space program. The swabs were collected from parts of the space station where fuel wastes are discharged during the engine's operation.

After these samples were sent back to Earth, scientists back home discovered something curious.

“It turns out that somehow these swabs reveal bacteria that were absent during the launch of the ISS module,” said Russian cosmonaut Anton Shkaplerov, according to the Russian news agency TASS, on Monday.

“That is, they have come from outer space and settled along the external surface. They are being studied so far and it seems that they pose no danger," he added.

The origin of the microorganisms is not totally confirmed yet, however it’s unlikely to be any kind of extraterrestrial bacteria. TASS also notes that the bacteria were most probably brought onto the ISS via the crew’s tablet PC and other equipment that was contaminated with terrestrial bacteria.

Nevertheless, even though it isn’t quite ET, this is still a fascinating find. The cosmonauts also showed that terrestrial bacteria had managed to survive on the space station’s exterior despite being within a space vacuum for a number of years, cruising at an altitude of up to 435 kilometers (205 miles) in low-Earth orbit

It’s also worth remembering that temperatures fluctuate wildly on the space station. Temperatures on the ISS can vary between 121°C (250°F) on its sunny side and below -157°C (-250°F) on its dark side.

Whatever the origin of the bacteria, it sure had a hell of a ride.

Scientists are always interested to learn about bacteria and space. Just last month, researchers published a study where they sent cultures of E. Coli, the bacteria found in poop that can give you food poisoning, to the ISS. Bizarrely, they discovered that the E. Coli in the space cultures were far more resistant to antibiotics than cultures on Earth. They even managed to work out how and why this strange phenomenon occurs.