5 ms·
Sounds slightly surprising, but the exterior of the ISS is not a sterile environment. There are thousands of ways terrestrial bacteria could have ended up there
by yosito 9y ago
Sounds slightly surprising, but the exterior of the ISS is not a sterile environment. There are thousands of ways terrestrial bacteria could have ended up there. I guess the interesting thing is that the bacteria seem to be able to survive the extreme environment. But that's hardly a new discovery about bacteria.
- agumonkey 9y agoWhat's there around ? solar rays for sure. Enough gazeous particules ? but that's it isn't it ?
- Florin_Andrei 9y agoMaybe it's a matter of time? I mean, there's quite a bit of UV from the Sun baking that surface every day. Perhaps those bacteria would eventually die if they are not being replenished from somewhere.
- askvictor 9y agoHere are some rough calculations on the matter: https://what-if.xkcd.com/117/ https://what-if.xkcd.com/117/
- QAPereo 9y agoRemember that human feces ended up in orbit, although not from recent sources.
- BeefySwain 9y agoThat sounds interesting. Do you have more info on that? A source perhaps?
- ams6110 9y agoEarly manned space capsules dumped human waste (at least urine) overboard. https://history.nasa.gov/SP-368/s6ch2.htm https://history.nasa.gov/SP-368/s6ch2.htm No idea what the Soviets did.
- astrodust 9y agoHow much energy would it take to get a bacterial cell into orbit? I'm guessing it's so little this could happen quite frequently in a violent storm.
- ufmace 9y agoOrbit is doubtful - what natural process could accelerate a bacteria to those speeds after getting it out of the atmosphere? Maybe some bacteria somehow floated up high enough to be hit by the ISS, but I would think they would be obliterated by the impact, despite being microscopic.
- JoeAltmaier 9y agoThe usual argument relies on meteor impact throwing detritus into the upper atmosphere. We have rocks from Mars that got here by that means.
- ufmace 9y agoMeteor impacts throwing debris into space can happen for sure, but we're talking about stuff that ends up on the outside of the ISS. The bacteria would have to be on something large enough to shelter it from the heat and wind of the original impact and high-speed passage through the atmosphere. It would have to end up in a stable orbit in the ballpark of where the ISS is. Surviving bacteria would then have to make their way out of this object and float around in space. And then their orbit drifts until they hit the ISS, mostly likely at very high speed unless they happen to be in almost exactly the same orbit. Feels pretty unlikely.
- astrodust 9y agoGiven kinetic energy is a function of mass, and bacteria way basically nothing it doesn't seem impossible for them to enter orbit, only improbable.
- ufmace 9y agoI may be rusty on my physics, but I think momentum/impulse is what you need here. You can throw all the energy you want at a bacteria or spec of dust or something, and you might vaporize it, but you aren't going to accelerate it to 20k mph relative to the surroundings, much less launch it out of the top of the atmosphere at those speeds. Even a bacteria is quite massive compared to particles that can hit those speeds by random collisions.