No scientist is going to tell you, without careful, rigorous study, that we’ve found aliens. The reason for that goes beyond getting forcibly fitted with a tinfoil hat: You’re making some pretty drastic claims about biology, chemistry, and possibly even the origins of life on Earth if you claim an alien has turned up, and extraordinary claims require extraordinary evidence. As a result, a Russian cosmonaut claiming he’s collected alien bacteria from the outside of the ISS is being greeted with skepticism and caution from scientists. But there is, indeed, a chance that alien bacteria has been found in orbit.
But, wait, don’t bacteria need, like, air, water, food and all that other fun stuff? Nope. In fact, in an experiment involving Earth bacteria, they were left clinging to the side of the ISS for nearly two years and were fine after being brought back inside in 2010. In fact, tiny organisms like bacteria and tardigrades don’t seem to give a crap about anything space-related. They just hunker down and wait it out. In fact, bacteria spread so fast, and are so hard to kill, NASA’s had to pioneer new ways to murder them.
So the next question is how they’d get into space, let alone the millions of light years it’d take to get to Earth? A recent theory has claimed that fast-moving “winds” (really dust clouds) in space can pull particles out of a planet’s atmosphere, including bacteria, and send them whizzing through the galaxy. Or perhaps an asteroid collision kicks rocks and dust high enough into the atmosphere that it spins off. Or, you know, maybe aliens aren’t good about getting rid of bacteria either, and we’re seeing the results of space launches from the distant past. The stuff with the rocks is a lot more likely, but hey, we’re talking about aliens.
So it’s possible. But we should note that doesn’t mean it’s a guarantee we’ve found alien life. Just applying Occam’s Razor, the ISS is much closer to a rock teeming with bacteria, Earth, than it is to the rest of space, and it’s far more likely the bacteria is from there. That’s still a fairly neat scientific bit of business, giving us another window into how these little buggers not only survive but thrive in the most extreme environment known to man. But, who knows? We very well might finally have had some alien visitors come say hi, no matter how tiny they may be.