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Bacteria on the outside of the International Space Station

independent.co.uk

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Re: Bacteria on the outside of the International Space Station

#31

Post by antonvs »

wil421 wrote: post #24
antonvs wrote: post #22

Earlier quoted context omitted.

If the alien organism originally evolved independently of life on Earth, then analyzing its genetic material - its equivalent of DNA - would tell us a lot. We haven't yet found any organisms on Earth that have evolved independently, so an organism found in space that has a different genetic structure from Earth life would be a good bet for being alien in origin. An alternative, albeit unlikely, possibility is that Ea…

If comets supposedly brought us water why not life? I just read an article yesterday about an asteroid from another solar system[1]. Maybe there was a Prometheus-esque comet with some single celled life in it. [1] http://time.com/5033026/mysterious-object-confirmed-another-...

Is is possible? Yes. Is it likely compared to the alternative? No.

Comets are theorized to have brought us water from within the solar system, so the comparison doesn't really apply unless life evolved in our solar system but somewhere other than Earth.

Here's some of what has to happen for life to cross naturally between planets in different solar systems:

0. Life evolves somewhere else

1. Somehow, some of that life ends up on an asteroid heading out of that solar system. The mechanism for this is pretty iffy. In the case of the ISS, we took those bacteria with when we launched, and they still haven't left Earth's gravity well.

2. That life survives the multi-millennia trip to another solar system, on an airless rock exposed to interstellar radiation for millennia.

3. The asteroid with life on it happens to hit a planet that can support that life.

4. The life isn't all destroyed in the blazing fireball caused by its descent through an atmosphere.

Each of those events has a probability, most of which are very low. To get the probability of the overall chain of events, multiply all the probabilities together, giving a much lower probability.

For life to evolve on Earth, all that's needed is step 0. Therefore, without even trying to assign actual numbers, we can see that the probability of life having originally evolved on Earth is far higher than it having come from somewhere else.

Re: Bacteria on the outside of the International Space Station

#32

Post by avian »

reubenswartz wrote: post #16
api wrote: post #2

I can't help but keep wondering if "life originated on Earth" might not be the last geocentrism. It's only speculation at this point but it's one I've harbored for many years. Part of this is because of how common we've found organic materials to be in the universe, and part of it comes from how poorly other geocentric ideas have fared.

There are plausible theories about how life arose on Earth. If you want to assume it came from somewhere else, you either have to invoke some kind of magic, or assume it happened somewhat along the lines that it would have done on Earth, then arrived somehow. It just kicks the can down the road without solving anything, IMO.

> It just kicks the can down the road without solving anything

Panspermia is an attempt to explain one inconsistency in our observations so far: it appears that life spontaneously emerging from inorganics is hugely unlikely. On other hand, geological records show that life appeared on Earth very soon after it became viable.

If life on Earth originated somewhere else, then this discrepancy can be made to disappear. For example, abiogenesis only needs to arise once within a large radius around Earth and within a much broader time margin. Hence it can be a very rare event while still not making early life on Earth a unique event in the universe.

I don't personally believe panspermia is likely. But it is a valid theory (although without much supporting evidence as far as I know).

Re: Bacteria on the outside of the International Space Station

#33

Post by JoeAltmaier »

antonvs wrote: post #31
wil421 wrote: post #24

Earlier quoted context omitted.

If comets supposedly brought us water why not life? I just read an article yesterday about an asteroid from another solar system[1]. Maybe there was a Prometheus-esque comet with some single celled life in it. [1] http://time.com/5033026/mysterious-object-confirmed-another-...

Is is possible? Yes. Is it likely compared to the alternative? No. Comets are theorized to have brought us water from within the solar system, so the comparison doesn't really apply unless life evolved in our solar system but somewhere other than Earth. Here's some of what has to happen for life to cross naturally between planets in different solar systems: 0. Life evolves somewhere else 1. Somehow, some of that life…

Bad conclusion. There are billions of 'other planets' and only one Earth. You'd have to add up the marginal probabilities of all the other scenarios, to compare with just the Earth scenario.

Re: Bacteria on the outside of the International Space Station

#34

Post by cup-of-tea »

otakucode wrote: post #29

Culture it, fill a probe full of canisters of the bacteria, and fire them directly at Europa. Spreading life should be of more importance than preserving the absurd idea of "pristine" environments for the selfish reasons of future scientists not wanting to do 4 minutes extra work determining whether the thing they observe occurred before or after human action changed things (as if such a distinction actually matters…

Why Europa? Why would you want to introduce a foreign bacteria that could potentially wipe out any possible life there? Why is spreading life important?

Re: Bacteria on the outside of the International Space Station

#35

Post by dashoffset »

greggarious wrote: post #26
antonvs wrote: post #22

Earlier quoted context omitted.

If the alien organism originally evolved independently of life on Earth, then analyzing its genetic material - its equivalent of DNA - would tell us a lot. We haven't yet found any organisms on Earth that have evolved independently, so an organism found in space that has a different genetic structure from Earth life would be a good bet for being alien in origin. An alternative, albeit unlikely, possibility is that Ea…

>An alternative, albeit unlikely, possibility is that Earth life was originally seeded from somewhere else - panspermia, https://en.wikipedia.org/wiki/Panspermia . I've seen this hypothesis before. I've also seen the oft repeated assumption that other intelligent life might be out there, more advanced than ours. Crazy though: what if we are the most advanced life in th universe?

https://en.wikipedia.org/wiki/Fermi_paradox#Intelligent_alie...

Re: Bacteria on the outside of the International Space Station

#37

Post by greggarious »

Sir_Cmpwn wrote: post #28
greggarious wrote: post #25

Doesn't the ISS blast human excrement out into space? Maybe that explains the bacteria ¯\_(ツ)_/¯

Actually, they ship it down to Earth during the resupply missions.

My bad, I may be crossing some wires and thinking of certain trains.

Re: Bacteria on the outside of the International Space Station

#38

Post by godelski »

This is CLEARLY clickbait. Why is this on the front page of HN? It is currently ranked #7!!

Article tldr: There's bacteria on the outside of the ISS. We've found some before and this isn't new. BUT THIS TIME IT MIGHT BE ALIEN!!! Why? Well... because it COULD be.

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