Implications of life being found or not found on Europa

[Feeble Wonk]

If we assume that Europa satisfies the criteria for being planets that could (possibly) support life, and we assume that no life is found on Europa, then we now how two data points: one with life and one without life. Assume that science finds no differences b If this calculation is reasonable, then the result would be that our expectation of life being present on hospital planets in other solar systems is cut in half.

I agree with your general premise Buzz. Conclusive failure to find life on Europa would definitely not be insignificant.
If nothing else, identifying the relevant differences between Earth and Europa (geothermal, biochemical, etc.) might yield very useful information regarding those factors most critical to creating and/or sustaining life (in whatever form). And if we believe upon thorough scientific consideration that the environmental/historical differences between Earth and Europa should not be significant, then we would have to conclude that life is more sensitive than we thought to other variables that we have not yet identified. That knowledge alone has scientific value.
Yet, even if we accept your rough estimate of a 50% decrease in the probability of finding life on other planets, we are still considering an uncountable number of potential planets. While I'm not really arguing that the cosmos is infinite, one might essentially consider it so... and 50% of infinity is still infinity... just a smaller infinity. I'd still be liking my odds of finding life taking root on billions upon billions of extraterrestrial planets.

 

[mfb]

What about 250 million years of micro-meteroid impacts? Violent shockwaves are just as lethal and much more common on asteroids than deep under the Earth's surface.

Micrometeorids are irrelevant if you are not at the surface.

@Buzz Bloom: you cannot divide E by half, that does not work. You can do Bayesian statistics, and the factor we have to apply for the central value will depend on the value and the probability distribution itself.
A real life example: You roll a die. What is the probability to get 6? Well, probably 1/6. You roll - it is not 6. What is your estimate for the next roll? Still 1/6, I guess, and certainly not 1/12.

Imagine we are quite sure that E is about 0.01. Finding no life on Europa would be perfectly in agreement with that expectation, and our estimate afterwards would still be close to 0.01.
On the other hand, if we guess E=0.9 but are not very sure about it, finding no life on Europa would reduce that value significantly.

 

[Norbert Fnord]

Not finding life on Europa would be just boring and of no particular consequence, but FINDING it, or finding life anywhere other than Earth, would be a big deal indeed.

I believe that if they find a significant quantity of liquid water with the usual common elements available and a source of energy (keeping the water liquid) but no life, that would be highly significant.
Currently, it appears that life appeared on Earth almost as soon as it was possible to do so. If it failed to develop somewhere else for over 4 billion years, Earth looks like a fluke. The consequent probability of life elsewhere in the universe diminishes enormously.

 

[Dr Wu]

Should life of whatever flavour be found on any of these 'igloo' moons beyond the solar system's snowline, then it seems highly likely that the cosmos does indeed teem with the stuff. This is life, moreover, that could be wholly independent of star-centred solar systems. The gravitational pull exerted by a Jovian gas giant, together with its retinue of satellites, would be sufficient for the encouragement of life virtually anywhere, even in the inter-galactic voids. . .

 

[newjerseyrunner]

Micrometeorids are irrelevant if you are not at the surface.

I concede about the microimpacts, but what about other impacts? Say your "home" is an asteroid about 50 feet across. Impacts from space debris hit at between 10 and 50 thousand miles an hour. How large of an impacter would it take to produce a violent shockwave that would rattle it too much all the way through? Remember, in space, cells wouldn't be flexible, they'd be frozen solid, so the slightest crack in the crystal structure of the water inside of them could potentially shred vital parts of the cell. Space, especially around young stars are shooting galleries. It'd be like trying to carry an ice sculpture from Paris to Berlin during WWII. It's a very different beast than surviving underground on Earth for 250my at a cozy temperature.

 

[Buzz Bloom]

I'd still be liking my odds of finding life taking root on billions upon billions of extraterrestrial planets.

Hi FW:
The above is related to three other terms in Drake's equation, but most strongly n_e:
R* = the average rate of star formation in our galaxy
f_p = the fraction of those stars that have planets
n_e = the average number of planets that can potentially support life per star that has planets
Not finding life on Europa is also likely to change estimates for n_e. The product

f_p × n_e × f_l = the fraction of planets in our galaxy that have life .​

However, I do not understand the role of the R* term, so I am here reinterpreting f_p as the fraction of stars in our galaxy that have planets.

I also take note of mfb's post #72. I agree with his correction to my oversimplified halving of f_l. The right approach would be to do a Bayesian calculation, but this requires estimating priors, and I do not have the background knowledge to do that.

Regards,
Buzz

 

[mfb]

Currently, it appears that life appeared on Earth almost as soon as it was possible to do so.

That is not a large factor. As far as I know, we cannot narrow down the formation of life better than something like a hundred million years. And complex life will probably die within a billion years, so if life would have formed 1.5 billion years later (for example) it could have been unlikely that humans evolved to study it. That gives us something like "it probably formed within the first 10% of the time span where it could have lead to human-like life" - not that much evidence.

I concede about the microimpacts, but what about other impacts? Say your "home" is an asteroid about 50 feet across. Impacts from space debris hit at between 10 and 50 thousand miles an hour. How large of an impacter would it take to produce a violent shockwave that would rattle it too much all the way through? Remember, in space, cells wouldn't be flexible, they'd be frozen solid, so the slightest crack in the crystal structure of the water inside of them could potentially shred vital parts of the cell. Space, especially around young stars are shooting galleries. It'd be like trying to carry an ice sculpture from Paris to Berlin during WWII. It's a very different beast than surviving underground on Earth for 250my at a cozy temperature.

Depends on the structure of the emitted material, but I guess impacts would have to be quite large to shatter the structure of tiny crystals inside.

 

[Feeble Wonk]

The above is related to three other terms in Drake's equation, but most strongly n_e:
R* = the average rate of star formation in our galaxy
f_p = the fraction of those stars that have planets
n_e = the average number of planets that can potentially support life per star that has planets
Not finding life on Europa is also likely to change estimates for n_e. The product

f_p × n_e × f_l = the fraction of planets in our galaxy that have life .​

However, I do not understand the role of the R* term, so I am here reinterpreting f_p as the fraction of stars in our galaxy that have planets.
I also take note of mfb's post #72. I agree with his correction to my oversimplified halving of f_l. The right approach would be to do a Bayesian calculation, but this requires estimating priors, and I do not have the background knowledge to do that.

My point was far less technical than this Buzz.
I fully concede that one could attempt to estimate the probable volume of "life-bearing" planets using a formulation like these, and I totally agree that Europa NOT having life would have to be factored into those calculations in such a way as to reduce that estimated volume.
I was simply noting that the number of water endowed rocky planets (known and unknown) orbiting in the Goldilocks Zone of stellar systems scattered through all of the galaxies in all of the galaxy clusters throughout the entire universe is so incalculably vast, even the reduced estimation would not diminish greatly my expectation that life is universal (even if somewhat less commonplace than might have been thought previously).

 

[EinsteinKreuz]

That is not a large factor. As far as I know, we cannot narrow down the formation of life better than something like a hundred million years. And complex life will probably die within a billion years, so if life would have formed 1.5 billion years later (for example) it could have been unlikely that humans evolved to study it. That gives us something like "it probably formed within the first 10% of the time span where it could have lead to human-like life" - not that much evidence.Depends on the structure of the emitted material, but I guess impacts would have to be quite large to shatter the structure of tiny crystals inside.

The fossil record shows that the oldest living organisms(at least 4*10⁹ years) are Cyanobacteria(that lovely green pondscum). These critters swarmed the early oceans(and still persist today in fresh and salt water all over the globe) and are the reason for the Oxygen in the atmosphere. Earth's early atmosphere was mostly CO2 but much of that CO2 was consumed by Cyanobacteria. I'd be quite astonished if it turns out that they are the ancestors of all living things as it's hard to imagine their evolutes losing photosynthesis capability. But I read that there have been successful experiments with UV photosynthesis of RNA from nucleotides using ZnS crystals as a substrate catalyst.No matter what the implications of no life on Europa, I still maintain that TITAN is a much better candidate despite the lack of liquid surface water as there is already some very interesting organic chemistry in its atmosphere and maybe on its surface that has yet to be fully explaine

 

[Buzz Bloom]

But I read that there have been successful experiments with UV photosynthesis of RNA from nucleotides using ZnS crystals as a substrate catalyst.

Hi Einstein:

I would much appreciate your posting a citation for these experiments.

No matter what the implications of no life on Europa, I still maintain that TITAN is a much better candidate despite the lack of liquid surface water as there is already some very interesting organic chemistry in its atmosphere and maybe on its surface that has yet to be fully explained

I have recently read about the possibility of a non-water based life on Titan from links in other posts in this thread. I even read speculations about the possibility of such life on Venus. I confess my main interest in exoplanet life derives from the Drake equation. Since it seems impossible to make any plausible estimates for of the n_e and f_l terms with respect to non-water life, these speculations seem less interesting than those that might derive from what is found on Europa.

Regards,
Buzz

 

[1oldman2]

Looks as if we may get some answers sooner than I expected.http://www.bbc.com/news/science-environment-36079069

 

[Norbert Fnord]

US will probably get there first as congress is forcing the issue with NASA.

http://arstechnica.co.uk/science/2015/12/congress-nasa-must-not-only-go-to-europa-it-must-land/

 

[1oldman2]

US will probably get there first as congress is forcing the issue with NASA.

http://arstechnica.co.uk/science/2015/12/congress-nasa-must-not-only-go-to-europa-it-must-land/

I was kind of envisioning a joint ESA/NASA project, If any exo-life is discovered it would be a good thing for our world to find it rather than just one particular nation. As a species we seem to be getting pretty good at joint space programs, hoping that trend continues.
That was an interesting article, thanks for posting the link. A "lander" would be a high priority part of the package, hopefully one that can penetrate the ice shell to sample whatever passes for an ocean on Europa. (I can't imagine a trip to Europa without Europe being involved)

 

[goat-on-a-stick]

I would think that it would constitute, among other things, very strong evidence that just having water on a planet/moon is not sufficient for life to evolve there.

Just having water ISN'T sufficient for life to begin there. Besides water, there's other factors such as heat, pressure, radiation, etc that should also be considered. Water is very important to life (as WE know it!), but I doubt that finding no life on Europa would suddenly make us re-evaluate how important water is to the formation of life.

Even if there is no life there, there could still possibly be a potential for life to be there. I would also not be so quick to deem a sampling size of two planets as "very strong evidence".

 

[mfb]

I was kind of envisioning a joint ESA/NASA project, If any exo-life is discovered it would be a good thing for our world to find it rather than just one particular nation.

ESA+NASA together still represent just ~10% of the world population.
ESA doesn't have access to radioisotope generators, and missions to the outer planets without them are problematic (JUICE needs huge solar panels), and landing with solar panels doesn't work. ESA needs NASA support for anything landing on Europa.

Europe is interested in Europa, indeed.
In German that works even better, as the continent is also called "Europa" there.

 

[EinsteinKreuz]

ESA+NASA together still represent just ~10% of the world population.
ESA doesn't have access to radioisotope generators, and missions to the outer planets without them are problematic (JUICE needs huge solar panels), and landing with solar panels doesn't work. ESA needs NASA support for anything landing on Europa.

Europe is interested in Europa, indeed.
In German that works even better, as the continent is also called "Europa" there.

ESA could by Plutonium-238 from Russia to produce radioisotope generators...Or produce their own. France has plenty of reactors it could use for Pu238 production. And so could the USofA.

 

[1oldman2]

This seems relevant.
http://www.space.com/33011-life-building-blocks-found-around-comet.html
"With all the organics, amino acid and phosphorus, we
can say that the comet really contains everything to
produce life — except energy," said Kathrin Altwegg of
the University of Bern in Switzerland, the principal
investigator for the Rosetta mission's ROSINA
instrument.

"Energy is completely missing on the comet, so on the
comet you cannot form life," Altwegg told Space.com.
"But once you have the comet in a warm place — let's
say it drops into the ocean — then these molecules
get free, they get mobile, they can react, and maybe
that's how life starts."

 

[Buzz Bloom]

"Energy is completely missing on the comet, so on the
comet you cannot form life," Altwegg told Space.com.
"But once you have the comet in a warm place — let's
say it drops into the ocean — then these molecules
get free, they get mobile, they can react, and maybe
that's how life starts."

Hi 1oldman2:

Energy is certainly necessary, but from various discussions I have read it seems plausible that just adding energy may not be sufficient. Unfortunately I am unable to post citations about this at this time.

Regards,
Buzz

 

[1oldman2]

Hi 1oldman2:

Energy is certainly necessary, but from various discussions I have read it seems plausible that just adding energy may not be sufficient. Unfortunately I am unable to post citations about this at this time.

Regards,
Buzz

Hi buzz:
Looks like we are getting closer to solving the puzzle. I agree with you on the energy aspect, There just may be more to it than the "Frankenstein" recipe of lightening.

 

[KenJackson]

Energy is certainly necessary, but from various discussions I have read it seems plausible that just adding energy may not be sufficient.

You're right, just based on logic. Consider that the Earth has lots of iron ore, coal, and other minerals but it never gets assembled into steel on it's own, even though the combination is simple. But life requires billions of little amino acids to be carefully assembled in the right order. Energy doesn't assemble extreme order from disorder.

 

[Buzz Bloom]

Consider that the Earth has lots of iron ore, coal, and other minerals but it never gets assembled into steel on it's own, even though the combination is simple. But life requires billions of little amino acids to be carefully assembled in the right order.

Hi Ken:

I am OK with the concept that energy is sufficient to create complexity of out simplicity, given a very common context. The concept is called emergent phenomena. I found the book Genesis by Robert M. Hazen (2005) to be an excellent presentation of this concept in a very entertaining book. He describes four factors of the phenomenon (pgs 17-21).
1. The concentration of agents.
2. The interconnectivity of agents.
3. Energy Flow through the system.
4. Cycling of energy flow.

I have also been reading discussions of the plausible role of a large moon, like the Earth's moon, as a necessary ingredient for emergence of life in the form of the first cell.

The following are some previous posts about this concept.

https://www.physicsforums.com/threa...ot-found-on-europa.865903/reply?quote=5440460
https://www.physicsforums.com/threads/novel-idea-on-the-origin-of-life.851106/reply?quote=5369545​

Regards,
Buzz

 

[1oldman2]

Hi again, a little more here.
http://www.space.com/32995-jupiter-moon-europa-energy-life.html

 

[rootone]

If all the expected ingredients for life are there in a subsurface ocean that does make investigating the ocean potentially highly rewarding.
However is the ice crust thought to be something like tens of km,?
So not easy to get through it to the liquid water, but I suppose a very strong laser might work if the crust is just water ice.

As for the presence of other Moons contributing to kick starting of life through periodicity or something, well Jupiter has plenty of them.

 

[1oldman2]

However is the ice crust thought to be something like tens of km,?

The jury is still out on that one.
http://www.planetary.org/blogs/emily-lakdawalla/2011/3266.html
http://www.scienceforums.net/topic/56545-estimating-europas-ice-crust-thickness/
http://www.lpi.usra.edu/resources/europa/thickice/
http://www.unisci.com/stories/20014/1109013.htm

If all the expected ingredients for life are there in a subsurface ocean that certainly makes investigating the ocean potentially highly rewarding.

It seems almost criminal not to check out the possibility.

 

[rootone]

Thanks for the interesting links.
You never know, there could be a highly evolved lifeform in there trying to figure out if Europa infinite or not

 

[1oldman2]

Thanks for the interesting links.
You never know, there could be a highly evolved lifeform in there trying to figure out if Europa infinite or not

This one is certainly relevant.
http://onlinelibrary.wiley.com/doi/10.1002/2016GL068547/pdf

 

[Dr Wu]

I'm with newjerseyrunner here. I'm prepared to go even further: given what we don't know about the possibilities of life existing elsewhere in the universe, life could even exist - even thrive - in that hellhole we call Venus. On the other hand, in the absence of ever discovering extraterrestrial life, it could be that we, our future selves, may never find out for sure whether Earth is truly unique as a life-bearing planet. This uncertainty could hang over us as long as we exist as a species; a depressing thought, but one that has to be considered.

 

[Buzz Bloom]

it could be that we, our future selves, may never find out for sure whether Earth is truly unique as a life-bearing planet. This uncertainty could hang over us as long as we exist as a species; a depressing thought, but one that has to be considered.

Hi @Dr Wu:

I am curious about how you would assess with respect to "a depressing thought" the role of a level of confidence in terms of an estimated probability, or range of probabilities, that the Earth is unique with respect to hosting life. Such an estimate would be based on accumulated future evidence combined with improvements in theoretical understanding about the possible processes that lead to life emerging from non-life. How depressing a thought would it be, for example, if humans never achieve an estimate of 100% certainty, but merely an estimate of say 99%? Also, would it make a difference if the estimate was restricted to a particular kind of life, say for example water and carbon based, rather than open to include any kind of theoretically possible life, such as "theoretically" that which might exist on Venus?

Regards,
Buzz

 

[1oldman2]

http://www.space.com/26905-jupiter-moon-europa-alien-life.html
http://news.nationalgeographic.com/news/2009/11/091116-jupiter-moon-life-europa-fish_2.html
http://science.jpl.nasa.gov/projects/Europa%20Mission/
http://science.jpl.nasa.gov/people/Pappalardo/
http://www.space.com/15498-europa-sdcmp.html
http://www.space.com/29732-jupiter-moon-europa-ocean-submarine.html

 

[Dr Wu]

Hi Buzz,

Yes, while I'm entirely open to the possibility of life existing on Enceladas, Europa and Ganymede - and indeed hope very much that this turns out to be true - I also have to accept the possibility that all three moons may turn out to harbour no life whatsoever. How would I feel about this? Deeply disappointed certainly, though not to the point of strain. If, on the other hand, it becomes apparent over time that the universe at large is indeed bereft of life, other than here on Earth, then, yes, that for me at least is a depressing thought. Can we ever be sure that such an assessment is truly valid, however? Not while we're dealing with incomplete information. . . which is always liable to be the case, as in other aspects of scientific enquiry. And there is always, but always, the unexpected to consider - re. Hume's 'Black Swan' theory. Personally, I belong to the universe-is-teeming-with-life camp (and not necessarily carbon-based life either). Somehow it seems almost inconceivable that we earthlings are alone in the wider (or even nearer?) Cosmos. Nevertheless, I still have to accept that the inconceivable remains a possibility, no matter how improbable or implausible it may appear to us pattern-loving monkeys. Now what would really be depressing is the realisation - should it ever come to pass - that we Homo sapiens are the sole intelligent life-forms 'currently' existing in the universe. ACC finds the prospect 'terrifying'. I find it depressing. Again we might never know for certain whether this solitude of ours is a verifiable scientific fact. And yet we just might one day. . . and by means that we cannot even begin to imagine. In the meantime, bring on the microbes. . .

 

[1oldman2]

Greetings and happy memorial day,
I wonder what effect or consequence the intense radiation found in the Europa environment would have on the development of life there. I haven't noticed that factored into the odds.

 

[rootone]

How much of the intense radiation around Jupiter can penetrate through Europa's ice crust though?
I think probably it's not much.

 

[Buzz Bloom]

Hi Dr Wu:

I think I failed to make my question clear. Maybe it will help if I explain my orientation.
1. I believe it is always impossible to ever be certain about any negative.
2. Any phenomenon that may be considered to be plausibly possible is likely (e.g., probability > 50%) to exist somewhere in our infinite universe. However, if life not found to exist in our galaxy, other than on Earth, it is extremely unlikely (probability < 0.01%) it will ever be found elsewhere in the universe. I think that to make such a finding will require assessing the atmospheric components of a planet in another galaxy, and finding free oxygen gas, O₂. My guess is that will not ever be a practical possibility, even for Andromeda.
3. At the present time, I find that any possibility of life not based on carbon and water is only at most a plausible speculation. Therefore, in the absence of what might be sought for as a high likelihood indicator of success, it is not currently possible to scientifically to make any kind of probability estimate about this possibility.

So, If we ignore the possibility of certainty regarding a negative finding, suppose we assume no positive finding, and that science eventually learns a lot about the details of requirements for carbon and water based life to evolve from non-life. Then if we also assume for the purpose of this question that science makes an estimate that the likelihood of finding life based on carbon and water existing in the galaxy elsewhere than on Earth is, say < 1%.

How would that 1% estimate make you feel? At what level of probability estimate, higher or lower, would your feelings be different?

Regards,
Buzz

 

[1oldman2]

How much of the intense radiation around Jupiter can penetrate through Europa's ice crust though?
I think probably it's not much.

I'm sure that will be studied in detail when a probe arrives to penetrate the ice, until then we can extrapolate at best. The "deck" that is Europa has a lot of wild cards in it.

 

[mfb]

It doesn't matter whether the radiation can penetrate the first 1 or 10 meters, it is completely irrelevant after 100 meters, and the layer is at least several kilometers thick.