Implications of life being found or not found on Europa

[jim mcnamara]

Comets have bombarded most any larger sized object in the Solar System. So whatever organic chemicals you can find on a comet has a very good chance of existing on a large moon.

Latest report - ribose (sugar that is part of RNA) "found" on comets: the space.com version
http://www.space.com/32503-artificial-comet-creates-life-building-blocks.html

 

[newjerseyrunner]

Cells as old as 250 million years can be revived. 20 km/s are ~7 light years per million year, sufficient to travel from one planetary system to a different one. Sure, interstellar space gives much more radiation damage than rock on Earth, but we have a safety factor of at least 250 in terms of time.

Yeah, but surely you agree that stowing away on an asteroid through interstellar space is a different kind of beast than sitting cozy under the ground of Earth for 250 million years. In space, every pice of space debris hits your asteroid with the power of a bullet and dowsed in radiation.

 

[anarchean]

http://www.space.com/32503-artificial-comet-creates-life-building-blocks.html

That's amazing! The organic material on Earth could come from asteroids too. Pretty cool.

That leaves one question open, how did this organic materials are formed in the steroids?
Do you know any hypothesis?

 

[rootone]

how did this organic materials are formed in the steroids?

Carbon is quite a common element found throughout the Universe.
So also are two other elements necessary for life as we know it, Oxygen and Nitrogen.
All of these are cooked up in considerable amounts by fusion inside medium to large stars.
The carbon in comets and asteroids would have been already present in the original solar nebula before any solid bodies formed.

 

[mfb]

Yeah, but surely you agree that stowing away on an asteroid through interstellar space is a different kind of beast than sitting cozy under the ground of Earth for 250 million years. In space, every pice of space debris hits your asteroid with the power of a bullet and dowsed in radiation.

Radiation is the only difference for those crystals that do not break up. The radiation dose depends on the size of the object and the position of the bacterium inside. 10 meters of rock give similar shielding as the atmosphere of Earth.

 

[litup]

The first thing I would want to know, assuming we found life on Europa, is this life form based on something like our style of DNA and RNA. If so, that life probably originated independently and it would say for instance, maybe our kind of life came from a cloud that seeded the whole solar system with prebiotic molecules that had a statistical chance of forming our kind of life, based on DNA and so forth.

If the life form was based on a structure like a 4 sided DNA kind of thing, it might be telling us there are many other ways of making life in the universe than just what we already know.

 

[Buzz Bloom]

Hi anarchean:

You are saying that if we don't find life of Europa, that will make possible for us to compare our environment with Europa's and possibly lapidate our current hypothesis for chemo-genesis. Right?

Yes. BTW, I learned a new word today: lapidate: 1. to pelt with stones 2. to kill by stoning. Nice metaphor.

Does Europa have material for creating organic stuff? I mean, there is carbon material there enough to create carbon-chain molecules

http://www.nasa.gov/topics/solarsystem/features/europa20130404.html

Regards,
Buzz

 

[newjerseyrunner]

Radiation is the only difference for those crystals that do not break up. The radiation dose depends on the size of the object and the position of the bacterium inside. 10 meters of rock give similar shielding as the atmosphere of Earth.

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.

 

[Feeble Wonk]

Hi phinds:

I confess I am surprised by this answer. 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.

Regards,
Buzz

I'd agree with you in some respects Buzz. If multicellular life was found I'd think that would provide strongly compelling evidence (convincing evidence IMHO) that life in "some" form will be extremely common on most life-compatible planets in the "Goldilocks Zone" of countless stellar systems of sufficient age scattered throughout the cosmos. But even only unicellular life on Europa would be significant evidence of that.

On the other hand, as already suggested, if the life form(s) found on Europa had a demonstrably common genetic ancestry with Terran life, it would essentially confirm panspermia AT LEAST WITHIN OUR SOLAR SYSTEM. Yet, that might actually be less compelling evidence that life is common throughout the cosmos as a whole, when compared to the implications of finding life on Europa of independent genetic origin. Though, I would agree with the other opinions that failure to find life on Europa would not significantly diminish expectations of life being present on more hospital planets in other solar systems.

 

[Buzz Bloom]

failure to find life on Europa would not significantly diminish expectations of life being present on more hospital planets in other solar systems.

Hi FW:

The estimate of "expectations" would seem to be related to the f_l term in Drakes equation:

f_l = the fraction of planets that could support life that actually develop life at some point​

Why is it unreasonable to calculate an estimate as follows.

Based on what is now known, mostly from knowledge of life on one single world with life (Earth), an estimate is made:

f_l = E.​

The uncertainty of this value would of course be very large.

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 between Europa's and Earth's that science believes to be significant enough to change our classification of Europa as a being a kind of planet than can support life. I suggest that it would then be reasonable to modify our estimate form

f_l = E​

to

f_l = E/2 .​

Assume we ignore the possibility of life migration from one planet to another. 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.

Regards,
Buzz

 

[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.