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Where in the solar system would you like to see a sample returned from most?


nhnifong

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So far, we've only returned samples from the Moon, one comet, and some interplanetary dust. (sorry hayabusa)

If we were to launch a sample return mission to any body in the solar system, what would would want to see most?

I think a multi-material sample from Titan would be the most interesting. To get a little of it's upper atmosphere, some of it's lower atmosphere, a little mud, a few pebbles, and some of that liquid methane that forms lakes on the surface. All that could be done with a landable glider holding a robotic arm and a pegasus-style rocket underneath with chambers designed for each kind of sample.

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Titan! There are several places in Solar System where life may exist. But if there is some life, say, on Mars, it could have gotten there from Earth. Or vice versa. We already know that organic materials can be lifted off the planet and end up on another planet, and we know that there are bacteria that can survive such a trip. So it'd be a hell of a discovery, but not necessarily a discovery of alien life.

But Titan... If there is life there, of which there is some indication, it would be very different from life on Earth, making common origin with Earth's life extremely unlikely. If there is life on Titan, we go from one planet on which life evolved to two planets on which life evolved in a Solar system. We go from one point of data, which is useless, and tells us nothing about life in the rest of the universe, to two points of data, from which we can make an estimate for probability of life elsewhere. And if there is, indeed, life on Titan, it would mean that the galaxy is absolutely teeming with life.

So yes, if there is one place in this Solar System that I would want to see a probe returned from it would be from Titan's soil.

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So that begs another question: If sufficient funding only exists to support either

a) more manned missions to LEO or maybe a future return to the moon or an asteroid

B) sample return missions to places like Titan, Mars and Europa

Which do people prefer? Myself, I would prefer that there was a greater focus on robotic missions. Manned missions are too expensive and result in all of our eggs being in one proverbial basket. On the other hand, the world's space agencies could accomplish several scientifically valuable and impressive robotic missions for the same money as is currently being spent on the ISS.

Edited by PakledHostage
Changed LKO to LEO... Oops!
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Titan! There are several places in Solar System where life may exist. But if there is some life, say, on Mars, it could have gotten there from Earth. Or vice versa. We already know that organic materials can be lifted off the planet and end up on another planet, and we know that there are bacteria that can survive such a trip. So it'd be a hell of a discovery, but not necessarily a discovery of alien life.

I do share your train of thought here absolutely.

But... If any life form can survive the process of being hit by a meteor so hard that it gets accelerated to escape velocity and then survive several months in space and then survive re-entry and impact we are probably not talking about life but simple molecule chains. Those simple molecule chains could as well be present in any comet and have been seeded all over the solar system for billions of years.

I personally love Titan but I think it's overhyped because of its geology that looks so earth like (and fascinating). However, it's raining methane there, I think liquid water remains the most promising candidate for finding low life forms.

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So that begs another question: If sufficient funding only exists to support either

a) more manned missions to LEO or maybe a future return to the moon or an asteroid

B) sample return missions to places like Titan, Mars and Europa

Which do people prefer? Myself, I would prefer that there was a greater focus on robotic missions. Manned missions are too expensive and result in all of our eggs being in one proverbial basket. On the other hand, the world's space agencies could accomplish several scientifically valuable and impressive robotic missions for the same money as is currently being spent on the ISS.

Yea I agree. More robotic spaceflight. Manned spaceflight is a very political act and not so much science related.

Now that you come up with realism I would rather have a 20 m sediment probe from mars analysed (not necessarily brought home) than a spoonful of any of the awesome moons.

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But... If any life form can survive the process of being hit by a meteor so hard that it gets accelerated to escape velocity and then survive several months in space and then survive re-entry and impact we are probably not talking about life but simple molecule chains.

Nope. Actual bacteria can survive all that. The trick is being really small, making them extremely resistant to extreme accelerations. And we do have extremophiles here on Earth that can survive the entire ride. In all likelihood, this has happened. There is just no telling if they ever managed to land anywhere hospitable enough for these few stray colonies to turn into a population.

I think liquid water remains the most promising candidate for finding low life forms.

Probably. But that's kind of the whole question here. Panspermia aside, if we confirm life in liquid water, we are right back to our standard habitable zone definitions. Nothing new, really. If we find life that survives in liquid methane without water at all, then we are talking a whole new ball game. If water as solvent isn't critical, if all you need is some kind of solvent, we suddenly go from some systems having potentially habitable worlds to most systems having habitable worlds.

Isn't that a discovery worth hunting for?

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You hope that life can exist on a non-water basis to prove your point. The scientific approach this not is (fake Yoda quote)

What I hope for is irrelevant. We know that life can exist with water as solvent. Finding life that uses water as solvent tells us nothing about the rest of the universe. Finding life that uses some other solvent gives us information. Not finding life on Titan would also give us some information, something to think about in terms of reasons why it's not there, but it isn't much, I grant you. But science is all about the long shots. Looking for things that don't work the way you expect. Scientists at particle accelerators aren't looking for ways to confirm standard theory. They are looking for places where it doesn't work, fully expecting to find nothing, which is what will happen most of the time. And when you find nothing, you move on. But if you do find a contradiction, if you do find an exception to the rule, that's where all the science happens.

You may find life on Mars, or Europa, or Enceladus. But that will tell you next to nothing. It's like finding a new way to demonstrate that gravity works. It'd be really neat if you can find some novel way to do it, but we learn nothing. Nothing changes. Compared to that, looking for some way in which gravity might not work the way we all think it does is an effort better spent, even though you are most likely not to come up with anything. Just the same, search for life on Titan would be far more productive even if we were all but convinced that we would find nothing.

Looking for life in unlikely places is very important. We already checked the Moon and have a pretty good idea about some other vacant rocks in space. We found nothing there. So barren rocks don't work for life. If the requirement for life is liquid water, then pretty much anything out there can be closely approximated here on Earth, and we already can look for life in unlikely places here on Earth. (And we found it almost everywhere.) But Titan provides us with a totally unique environment. It is an unlikely place for life, at least anything like Earth's life, and yet has many of the features required by some form of life in principle. That is the place to look. That is the place that has potential for most knowledge gained. It might turn out to be a wasted effort, but it is the highest possible payoff for roughly equivalent investment.

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@K^2p

Hm. Nice speech.

You may find life on Mars, or Europa, or Enceladus. But that will tell you next to nothing. It's like finding a new way to demonstrate that gravity works.

Nah, sorry, you are falling for wishful thinking here instead of being rational. It would obviously tell us A TON if we found traces of past or present life on these bodies.

Your reasoning is that of a gambler. If we find life in the most unlikely spots we hit jackpot. True, but is that a reasonable approach?

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Nah, sorry, you are falling for wishful thinking here instead of being rational. It would obviously tell us A TON if we found traces of past or present life on these bodies.

Your reasoning is that of a gambler. If we find life in the most unlikely spots we hit jackpot. True, but is that a reasonable approach?

You are misunderstanding.

The point isn't to find life. If we wanted to find life, all we'd need to do is look around on Earth. The name of the game here is describing life - specifically, where can life exist, and where can it not.

Finding evidence of (past) life on Mars would be a big discovery, true. It would tell us quite a lot about the evolution of life, and about possible panspermia. The problem is that we already know (or, at least, have reasonably strong evidence to support) that Mars in the past hosted an environment not terribly dissimilar from Earth. Therefore, life on Mars will be life as we know it (or, at least, life as we reasonably expect it).

Life on Titan is a completely different matter. If it exists, it must make use of an entirely different chemistry than life on Earth, due to the lack of water as a solvent. Therefore, any putative life on Titan would be life as we don't know it. A much bigger discovery, in the grand scheme of things.

This has nothing to do with gambling. Science isn't about picking one number and hoping for the jackpot. Science is about picking all of the numbers and finding out whether or not the jackpot exists. The jackpot here would be life as we don't know it; Titan is only one of the numbers, but arguably the most promising. Why not pick it?

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Titan is certainly intriguing, but I think the point many of us are trying to make is "let's go after the low hanging fruit first". Follow the water, to borrow a phrase.

"Where in the solar system would you like to see a sample returned from most?"

It's not like I'm going to oppose to more samples from Mars along the way, or anywhere else, really. And if we have to work up to it, we have to work up to it. But if we pick one place, and one place only, I can think of no better place than Titan.

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There is an anomaly that needs to be investigated on titan. There is an unexplained deficit of hydrogen and a surplus of acetylene at the surface. This suggests a hydrogen cycle wherein acetylene is photodissociated in the upper atmosphere, creating molecular hydrogen, which diffuses into the lower atmosphere, and is combined with carbon from the surface to produce more acetylene to diffuse back into the upper atmosphere. Right now, the best explanation for the process catalysing the reaction is probably life, and this is part of it's metabolism. In my opinion, it is imperative that we follow up on these observations with a sample return mission.

http://www.astronomynow.com/news/n1006/10titan/

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You are misunderstanding.

The point isn't to find life. If we wanted to find life, all we'd need to do is look around on Earth. The name of the game here is describing life - specifically, where can life exist, and where can it not.

Finding evidence of (past) life on Mars would be a big discovery, true. It would tell us quite a lot about the evolution of life, and about possible panspermia. The problem is that we already know (or, at least, have reasonably strong evidence to support) that Mars in the past hosted an environment not terribly dissimilar from Earth. Therefore, life on Mars will be life as we know it (or, at least, life as we reasonably expect it).

Life on Titan is a completely different matter. If it exists, it must make use of an entirely different chemistry than life on Earth, due to the lack of water as a solvent. Therefore, any putative life on Titan would be life as we don't know it. A much bigger discovery, in the grand scheme of things.

This has nothing to do with gambling. Science isn't about picking one number and hoping for the jackpot. Science is about picking all of the numbers and finding out whether or not the jackpot exists. The jackpot here would be life as we don't know it; Titan is only one of the numbers, but arguably the most promising. Why not pick it?

Problem on Titan is not the lack of water its plenty of ice but the low temperature. -180 degree would not make for fast chemical reactions and your main concern would be to avoid the life form to freeze solid.

now deep below the surface it will be far warmer making it more livable but where the situation would again be more like Europa and other ice moons with all the organic molecules as an major bonus.

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Low temperatures aren't a problem either. So long as there is an energy flux that can be utilized, any activation potentials can be adjusted to allow for metabolism at reasonable rate. It's not a question of whether it is possible for a form of life to exist that can thrive on Titan. Everything we know says yes. It's a question of whether the conditions there were right for such life to evolve. Requirements for the later are far less clear, and it's part of what we need to understand about general principles of life before we can speculate about life outside of Solar System.

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Low temperatures aren't a problem either. So long as there is an energy flux that can be utilized, any activation potentials can be adjusted to allow for metabolism at reasonable rate. It's not a question of whether it is possible for a form of life to exist that can thrive on Titan. Everything we know says yes. It's a question of whether the conditions there were right for such life to evolve. Requirements for the later are far less clear, and it's part of what we need to understand about general principles of life before we can speculate about life outside of Solar System.

You two are right, I thought that the other building blocks of life would be frozen solid however they would be dissolved in the solvent.

So yes hydrocarbon as an solvent for life might be possible.

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Nope. Actual bacteria can survive all that. The trick is being really small, making them extremely resistant to extreme accelerations. And we do have extremophiles here on Earth that can survive the entire ride. In all likelihood, this has happened. There is just no telling if they ever managed to land anywhere hospitable enough for these few stray colonies to turn into a population.

More probably that life jumped from mars to earth, look like it was just as habitable 3 billions years ago and the escape velocity is just an fraction.

Bringing up the gas giant ice moons with its tiny gravity. Bacteria get frozen in ice the an impact kick them into Jupiter (not Jool :)) orbit, the moons slingshot them everywhere.

They would many of the ice blocks would be sized, could bacteria survive being frozen for millions of years?

Probably. But that's kind of the whole question here. Panspermia aside, if we confirm life in liquid water, we are right back to our standard habitable zone definitions. Nothing new, really. If we find life that survives in liquid methane without water at all, then we are talking a whole new ball game. If water as solvent isn't critical, if all you need is some kind of solvent, we suddenly go from some systems having potentially habitable worlds to most systems having habitable worlds.

Isn't that a discovery worth hunting for?

Difference between life on ice moons and earth, also diferent ice moons would show if life happen once or multiple times. However it might even be an combination, life evolves easy but the first attempts looses out to more efficient alien invaders and this would be hard to prove.

Life on Titan would be amazing, solvent would still be critical however you don't need water. But it would show that life is common as Titan life could not come from other places in the solar system. Still a long shot, would land an better laboratory first.

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