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.
(However, if it somehow turns out to be alien, that seems to be to imply that interstellar space must be swarming with bacteria, yes? For the ISS to have encountered some already?)
You're probably right in this case, but as for the last part consider that the Earth is a gravity well and the ISS has been in space for a very long time. Earth is going to draw in particles and the ISS has had plenty of time to catch them.
Sure, but we aren't holding to this form of biological geocentrism for no reason. We've never seen any definite proof of life on any other planets. Given that science is an evidence-based methodology, it makes sense that we would assume Earth-based life is the only model of life until proven otherwise.
If we want to be perfect logicians, then there is no reality or absolute truth in anything, but that's just a bit pedantic IMO ;) Conclusions at some point need to be made to progress.
Hi jackmott FYI you are "hellbanned" which means nobody can see your comments. I'm sorry to be the bearer of bad news. The mods on this site are overly strict and quick to employ such a harsh tactic, IMO.
It's worth noting that geocentrism wasn't held onto for no reason either. At least the ancient Greeks had solid logical reasons for believing it: if the Earth orbited the sun, then there would be parallax visible between the stars since the Earth's position among the stars is changing throughout the year. Yet, there is none. Therefore the Earth is fixed in space.
The error of course is that the stars are really unimaginably far away and hence there is parallax but it's practically indiscernible. The Greeks thought the stars being that far away was the less likely answer to the apparent lack of parallax than the Earth simply being the center of the solar system.
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.
The hypothesis that life on Earth originated elsewhere is somewhat independent of abiogenesis, really. At least in my experience, most supporters of the former also support the latter.
> 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).
It's certainly a valid hypothesis. And stronger (any?) evidence for possible life on Mars or Venus would possibly support this.
With a sample size of 1, and loose record-keeping from ~4B years ago, it's hard to tell, but we don't really know if it took life 1 day or 500M years to evolve once it was chemically/geologically viable. We do know that life was very primitive for > 1B years (not even eukaryotic, let alone multicellular).
We also know that space isn't teaming with little biologically active spores from other worlds (unless it is and the government is covering it up, of course), which suggests that in the vastness of space, life doesn't really hitch rides on asteroids or comets and colonize the galaxy accidentally. And if some beings were doing this on purpose, why not send more advanced life forms or robots?
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.
Maybe 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.
Orbit 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.
Meteor 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.
I 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.
The suggestion that the bacteria is extraterrestrial in origin is absolutely ridiculous. Much, much, much more research is necessary before such a claim can be made. The speculation on Shkaplerov's part is hugely unprofessional.
Shkaplerov appears to be a very accomplished pilot - see https://en.wikipedia.org/wiki/Anton_Shkaplerov. It's not clear why anyone would pay attention to his claims about exobiology. The journalism is unprofessional, too, although that's not news.
Couldn't this simply be from an astronaut sneezing on a glove prior to a spacewalk, then grabbing a handrail? We already know about water bears that can survive in space, so why not bacteria.
Pretty much - even opening the air lock will do it.
> The former cosmonaut, who spent nearly a year in orbit back in the 1980s, said that outer surface of ISS is “heavily contaminated” by the waste products from engines of the arriving spacecraft, atmospheric discharges from the station during spacewalks by the crew and other factors.
There is also evidence that bacteria get carried up on air currents and the ISS orbits low enough that it can intercept this stuff. (note that while this is widely reported, there doesn't seem to be anything actually published, and the air current theory is, well, a theory).
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 Earth life was originally seeded from somewhere else - panspermia, https://en.wikipedia.org/wiki/Panspermia.
In that case, Earth life and (some) alien life would have a common origin, and we'd have to examine the differences in its DNA to find out more about its history.
Even in that case, it ought to be possible to determine that the organism had branched off from Earth life long enough ago to make it a candidate for alien life.
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.
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.
But of those billions of other planets, as they get further and further away, the probability of an asteroid from them finding Earth goes down. So does the probability of life on the asteroid surviving the trip.
I think that the number of planets within a distance R is O(R^2), but the probability of an asteroid from such a planet reaching us is O(1/R^2). But if the probability of life on the asteroid surviving the trip decreases with a longer trip, the net effect is probably that the further-away planets contribute little to the probability of life reaching us in this way.
The panspermia idea is, that it started somewhere and somewhen, and has been planet hopping ever since. We only need one nearby life-bearing planet to seed earth; it got seeded from further away and so on.
Similar to how ancient Romans wore silk but didn't have trade with China. It only took each trader to trade with their neighbor, and silk could travel thousands of miles.
OK, but at that point, the "billions of planets out there" argument doesn't work. You're left with the probability of it transferring from a nearby planet.
Right, and the inevitability of it being present in a nearby planet went way up. Because once it started somewhere (and there are billions of 'somewheres') it would spread like a virus and infect every possible receptive environment.
The statistics is hard. No simple counting of planets is enough. All the vectors have to be accounted for.
No, the inevitability of it being present in a nearby planet went way up if the probability of it moving from one planet to another planet is decently high - and not otherwise.
No, it doesn't. If the probability per year is 10^-15, then the probability over 10 billion years (10^10) is still 10^-5. (I mean, yes, over a quadrillion years the probability approaches 1.0, but I don't think that helps your position.)
You keep trying to say "but big numbers of planets, and big amounts of time" to make this idea reasonable. But it doesn't work. You have to deal with how low the probability actually is of it happening from one planet in one year. If that's low enough, you can't salvage it just by saying "billions of years and billions of planets".
...and you can't refute it by making up tiny numbers.
Statistics is hard and you can be fooled by big/small numbers. Until some reasonable estimate of the actually probability of an asteroid making it from one system to another (oh look! There's one in our system now!) you can't make conclusions.
> You'd have to add up the marginal probabilities of all the other scenarios, to compare with just the Earth scenario.
There aren't even close to billions of other planets that could have been candidates for sending a life-bearing asteroid to Earth. Some of the restrictions are:
1. A planet capable of having developed life.
2. A planet close enough for an asteroid from it (I have trouble typing that because it's such an unlikely scenario) to have reached Earth around the time that life on Earth began. That was ~4 billion years ago, which seems like a lot, but consider that if the recently spotted asteroid 1I/2017 U1 had come direct to us from Proxima Centauri, the closest star, it would have taken at least 48,000 years to get here. That puts a limit on candidate sources of less than 100 times the distance to Proxima, and limits the number of star systems to ~2 million.
Even if you multiply the probabilities in question by a factor of 1e6 to 1e7, it's not going to change the conclusion.
Add in : asteroids in close orbits around suns developing life elsewhere (or here). Precursor chemicals to life surviving the asteroid trip even if whole organisms do not (accelerating life development on Earth by millions/a billion years).
We started with, it took an Earth to develop life, but if it came from elsewhere we'd have to expand our ideas to include all other possible sources of life, not just Earthlike. Because our premise changed.
How is your list any more remarkable than life starting on Earth in the first place?
What’s the probability of adding water and heat to a planet then waiting a few billion years for life? I hope we can send some probes to Saturns moons and find out. Even Mars could have a trace of life in the dirt.
Assuming that the above list has a 10% chance of happening, that would be 10 times more remarkable than life starting on Earth in the first place; since you'd have the probability of adding water and heat to a (non-Earth) planet and waiting a few billion years for life and that whole list as well.
We don't know precisely what the ideal concoction is for life to get started, nor can we measure how close to ideal our planet is relative to others. So maybe Earth is not the most efficient planet at developing life, and in that case, the probability equation could tip back to panspermia.
>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?
If the probabilities are such that it's feasible that we're the first/most advanced life in the universe, then (given our planets comparably young age) it's exceedingly likely that we're the only life in the observable universe.
It would be plausible for us to be alone, and it would be plausible for us to be one of the less advanced lifeforms among many, but it would be quite surprising if we'd to be the most advanced civilization among many; since many/most of them would have gotten a significant head start.
Did they get a head start though? All these atoms bouncing around started with the big bang after all :)
One theory I'm fond of is that we are not alone, but life is so rare that the distances between intelligent civilizations are too vast for us to ever observe them (or vice versa).
Many, many other planets had conditions suitable (as far as we understand what's suitable) for creating life when our planet didn't exist yet; out of all feasible planets we're younger than average, so others would have had a head start.
Earlier this year, Russian scientists announced that the "Test" experiments had found a range of different organisms that had been brought up from Earth and seemed to be surviving by clinging onto the ISS's hull.
The above quote from the article suggests to me that there is a good chance that some of the bacteria remained on the hull long after the experiments performed by the Russians earlier that year.
In any case, we know that they use special waste storage containers, and don't expose feces to space directly (presumably until these systems fail during re-entry - far away from the ISS). Take your pick of the several videos on YouTube that describe the ISS's toilet to see the waste containers in question.
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 in the slightest).
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?
Any type of leak can contribute to this bacteria. Maybe there is some benign bacteria that was stuck on the outside from earth that will thrive in such environment
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.
There are a handful of scientists attempting to collect life forms from very high altitudes using balloons. In one instance [1] they discovered UV resistant bacteria. Could it be remotely possible that high altitude species have managed to live on the ISS?
So... You found bacteria on your swab while orbiting the largest and only known source of bacteria in the universe and you think it might not be from that largest and only known source of bacteria? Bah!
If bacteria have survived on the surface of the ISS, I wonder what we have introduced to the Moon and Mars (and maybe Venus!) on landers. Perhaps they'll be covered in a biome soon.
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[ 5.3 ms ] story [ 142 ms ] threadIt'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.
Cf. https://en.wikipedia.org/wiki/Tersicoccus_phoenicis "It has only been found in two spacecraft assembly clean room facilities..."
Maybe it's not T. phoenicis but it's not ET.
(However, if it somehow turns out to be alien, that seems to be to imply that interstellar space must be swarming with bacteria, yes? For the ISS to have encountered some already?)
The error of course is that the stars are really unimaginably far away and hence there is parallax but it's practically indiscernible. The Greeks thought the stars being that far away was the less likely answer to the apparent lack of parallax than the Earth simply being the center of the solar system.
https://en.wikipedia.org/wiki/Panspermia
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.
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).
With a sample size of 1, and loose record-keeping from ~4B years ago, it's hard to tell, but we don't really know if it took life 1 day or 500M years to evolve once it was chemically/geologically viable. We do know that life was very primitive for > 1B years (not even eukaryotic, let alone multicellular).
We also know that space isn't teaming with little biologically active spores from other worlds (unless it is and the government is covering it up, of course), which suggests that in the vastness of space, life doesn't really hitch rides on asteroids or comets and colonize the galaxy accidentally. And if some beings were doing this on purpose, why not send more advanced life forms or robots?
solar rays for sure. Enough gazeous particules ? but that's it isn't it ?
https://history.nasa.gov/SP-368/s6ch2.htm
No idea what the Soviets did.
> The former cosmonaut, who spent nearly a year in orbit back in the 1980s, said that outer surface of ISS is “heavily contaminated” by the waste products from engines of the arriving spacecraft, atmospheric discharges from the station during spacewalks by the crew and other factors.
https://www.rt.com/news/181472-iss-marine-plankton-space/
There is also evidence that bacteria get carried up on air currents and the ISS orbits low enough that it can intercept this stuff. (note that while this is widely reported, there doesn't seem to be anything actually published, and the air current theory is, well, a theory).
There are several papers on interior contamination though, e.g http://www.sciencedirect.com/science/article/pii/S0923250805...
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 Earth life was originally seeded from somewhere else - panspermia, https://en.wikipedia.org/wiki/Panspermia.
In that case, Earth life and (some) alien life would have a common origin, and we'd have to examine the differences in its DNA to find out more about its history.
Even in that case, it ought to be possible to determine that the organism had branched off from Earth life long enough ago to make it a candidate for alien life.
Maybe there was a Prometheus-esque comet with some single celled life in it.
[1]http://time.com/5033026/mysterious-object-confirmed-another-...
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.
I think that the number of planets within a distance R is O(R^2), but the probability of an asteroid from such a planet reaching us is O(1/R^2). But if the probability of life on the asteroid surviving the trip decreases with a longer trip, the net effect is probably that the further-away planets contribute little to the probability of life reaching us in this way.
Similar to how ancient Romans wore silk but didn't have trade with China. It only took each trader to trade with their neighbor, and silk could travel thousands of miles.
The statistics is hard. No simple counting of planets is enough. All the vectors have to be accounted for.
You keep trying to say "but big numbers of planets, and big amounts of time" to make this idea reasonable. But it doesn't work. You have to deal with how low the probability actually is of it happening from one planet in one year. If that's low enough, you can't salvage it just by saying "billions of years and billions of planets".
There aren't even close to billions of other planets that could have been candidates for sending a life-bearing asteroid to Earth. Some of the restrictions are:
1. A planet capable of having developed life.
2. A planet close enough for an asteroid from it (I have trouble typing that because it's such an unlikely scenario) to have reached Earth around the time that life on Earth began. That was ~4 billion years ago, which seems like a lot, but consider that if the recently spotted asteroid 1I/2017 U1 had come direct to us from Proxima Centauri, the closest star, it would have taken at least 48,000 years to get here. That puts a limit on candidate sources of less than 100 times the distance to Proxima, and limits the number of star systems to ~2 million.
Even if you multiply the probabilities in question by a factor of 1e6 to 1e7, it's not going to change the conclusion.
We started with, it took an Earth to develop life, but if it came from elsewhere we'd have to expand our ideas to include all other possible sources of life, not just Earthlike. Because our premise changed.
What’s the probability of adding water and heat to a planet then waiting a few billion years for life? I hope we can send some probes to Saturns moons and find out. Even Mars could have a trace of life in the dirt.
Because the list includes that probability and adds a number of other extremely unlikely events that have to take place.
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?
It would be plausible for us to be alone, and it would be plausible for us to be one of the less advanced lifeforms among many, but it would be quite surprising if we'd to be the most advanced civilization among many; since many/most of them would have gotten a significant head start.
One theory I'm fond of is that we are not alone, but life is so rare that the distances between intelligent civilizations are too vast for us to ever observe them (or vice versa).
The above quote from the article suggests to me that there is a good chance that some of the bacteria remained on the hull long after the experiments performed by the Russians earlier that year.
¯\_(ツ)_/¯
Specifically "... is ejected from the station and burns ..." though there isn't much else to support for this.
According to the first link (PDF, sorry), waste is disposed of in re-entry craft.
But according to the second link, it's ejected to burn up in the atmosphere.
https://www.nasa.gov/sites/default/files/files/issrdc_2013-0...
https://www.nasa.gov/mission_pages/station/research/news/inf...
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.
[1] https://www.sciencedaily.com/releases/2009/03/090318094642.h...
click bait...