Life’s cauldron may be bubbling underneath Enceladus

By Phil Plait | March 26, 2008 2:20 pm

A few days ago I wrote about how the Cassini Saturn probe dove through water ice plumes erupting from the surface of the icy moon Enceladus. The pictures were incredible, but it may very well be that the other detectors got the big payoff.

They detected organic compounds in the plumes.

Now remember, organic molecules don’t necessarily mean life. What Cassini detected were heavy carbon-based molecules, including many that are the building blocks for making things like amino acids and other compounds necessary for life as we know it.

Edited to add: Carolyn Porco, imaging team leader for Cassini, says:

[…] it is now unambiguous that the jets emerging from the south polar fractures contain organic materials heavier than simple methane — acetylene, hydrogen cyanide, formaldehyde, propane, etc. — making the sub-surface sources of Enceladus’ dramatic geological activity beyond doubt rich in astrobiologically interesting materials.

It’s been supposed for some time that Enceladus, like Jupiter’s moon Europa, has a subsurface ocean. The surface itself is mostly water ice, implying strongly that any ocean would have water as well. The plumes erupt out from cracks in the surface, and when Cassini dove through them it got to directly sample the interior of Enceladus. And it tasted organic compounds, 20 times as dense as previously thought.


There was a second discovery as well: the cracks were much warmer than expected. They were at an admittedly chilly -93 Celsius, but that’s 17 Celsius higher than thought. Two plumes come from the warmest of these regions as well.

Coupled together, these two items indicate that if there is an ocean beneath the frozen crust of the moon, then it’s reasonably warm, and rich in organic compounds. We don’t know how life started on Earth, but it’s a good guess that an ocean thick with organic compounds was involved at some point.

This is a fantastically provocative and interesting development! The ingredients for life exist on a tiny moon orbiting a ringed giant, and better yet they sit in a mixing bowl that has been churning away for billions of years. What lies beneath that hidden face?

Comments (65)

  1. Michael Lonergan

    What is truly amazing is that the narrow “Goldilocks Zone” is having to be expanded. While we may not find Flipper’s cousin in this ocean, even the discovery of microbial life would be stunning.

  2. Heliopogenus

    The excitement of this discovery is muted by the realization that regardless of how amazing this is, by the time enough resources are allocated to investigate this further, perhaps half a century will have passed. We may all be dead and gone before there’s any follow up to this, because the idiots in Congress are too busy bickering over useless topics. It’s funny how non-chalantly some talk about the possible trillion that this war in Iraq will cost, when had a fraction of that been allocated to science, technology, research and development, and education, we would be well on our way towards properly investigating periplanetary life. I guess the acquisition of knowledge is not as important as the need for power, greed, and corruption.

  3. Edward

    The gas plumes, I assume, is “steam”. If so, would it condense and
    fall as snow?

  4. This is incredibly cool – but wait a while, as Cassini’s going to be taking an even closer trip in through the plumes.

    I can’t wait to see the media hype on this one..

    “OMG POSSIBLE LIFE ON ICY MOON OF SATURN OMG”

    (will editors use OMG in a headline? I bet they would…)

  5. TY

    This is quite interesting. I always found Europa to be one of the most mysterious moon’s and really enjoyed the fact we may go there to search for life sometime. I do hope sometime soon we actually send a probe below the surface of these moon’s and find life. That would make us so lucky to live in the time when life is first discovered outside of our planet!

  6. gopher65

    I wonder if these plumes on Enceladus could be tested for bacterial contamination? After all, they come from deep underground, right? I wouldn’t expect there to be anything alive in the plumes by the time they reach an orbiting probe, but maybe a test could still be devised that could search for life there. That seems a heck of a lot easier than trying to melt out way down through Europa’s crust 0_0. I wouldn’t make that the main point of a mission to Saturn, but it sounds to me like a great secondary objective for the next flagship class mission to Saturn (in like, 20 or 50 years).

  7. My god… it’s full of water.

  8. “The ingredients for life exist on a tiny moon orbiting a ringed giant, and better yet they sit in a mixing bowl that has been churning away for billions of years. What lies beneath that hidden face?”

    Creamy nougat?

  9. Gary F

    gopher: That’s an interesting idea. I’d imagine that if there were life on Enceladus, it would get ejected from the plumes and dead microbes would accumulate on the surface when they fell back to the ground. So a lander might be able to search for the dead microbes directly.

  10. andy

    So what we need to find out now is why the activity appears to be localised near the south pole of the moon, and how long it has been going on for (which may be a harder question to answer). It might be that this is a fairly recent and localised episode of melting, in which case Enceladus might be a world with numerous lakes beneath the surface, each lasting a (geologically) short time before refreezing… if that is the case, then despite the presence of water and organics it might still be a poor candidate for a habitable world.

  11. dave

    How do they explain the water on Enceladus? (and Europa?) Well I mean, beyond the usual explanation that involves aliens towing it there from another star system thousands of years ago (which of course, is how our moon got here).

  12. MandyDax

    jeremy:

    I can’t wait to see the media hype on this one..

    “OMG POSSIBLE LIFE ON ICY MOON OF SATURN OMG”

    (will editors use OMG in a headline? I bet they would…)

    Yes, but they notorious for not using “POSSIBLE” as it doesn’t sell as well.

  13. Kullat Nunu

    Um, has anyone informed Enceladus that it not supposed to have an ocean? I mean, the moon is [i]tiny[/i]! It should not be experiencing enough tidal heating, nor it should have enough radioactive isotopes, so why on Earth (…) Enceladus can have an ocean (or even a largish pocked of molten water?

  14. allkom

    That’s so cool . Intergalactic amino acids and now this ! won’t you stop amazing me . Makes me wonder if we will not soon be able to find “real” extraterrestrial life forms and shut up “CR” & “ID” people for good!!. On the other hand , they would not be convinced by anything revealed by scientists . At most they would “pray for guidance”.

  15. Derek

    No amount of evidence will ever convince the ID people that they’re wrong, as their belief are founded on religious conviction. They take pride from the fact that they are willing to believe such things on faith alone, believing it to be some sort of virtue for people to do so.

    But I agree that actual discovery of independently developing life would be a big shock for a lot of them. I hope it happens during my lifetime.

  16. marco sch.

    I’m pretty sure that extra-terrestrial life will be discovered in my lifetime (OK, I’m 45 and making assumptions about my life expectancy, let’s say 30 more years…)

    But I wonder where if it will be found first: in our solar system or around another star?

  17. asknot

    These results seem to me to completely invalidate the entire concept of a “Goldilocks Zone” at least insofar as it pertains to stars.

    Enceladus and Europa aren’t getting their energy from sunlight. Their distance to the sun is irrelevant with regards to their potential habitability. I don’t see how this would not apply to any icy body orbiting any planetary sized body irrespective of the presence of any nearby stars, say a brown dwarf or an ejected giant planet, (except for being too close and too hot). The habitable zone has just expanded to pretty much include the entire universe.

  18. How do they explain the water on Enceladus? (and Europa?)

    The standard explanation for Europa’s (and Ganymde’s) water is tidal heating. (The eccentric orbits bring the moons closer to and farther from Jupiter, changing the tidal forces causing flexing and therefore heating. The orbits are kept eccentric via resonances with other moons.)

    It isn’t clear that this works for Enceladus. Meyer and Wisdom found that it can’t be tidally heated in an equilibrium state, but then that could just mean that it’s going through changes at present. (Astronomers are always a little uneasy with that kind of explanation, though.) A large collisions is also possible, but it’s invoking a one-off event which is always kind of sketchy. I’m not sure what other options have been seriously floated.

  19. TheBlackCat

    Unfortunately, I would suspect that the presence of complex organic molecules would be evidence against life. At least on Earth those seem to have been eaten up pretty quickly.

  20. Jonathan

    I’ve been bouncing around like a kid with a birthday coming up ever since I read this, but I’m not clear on the “organic materials”. Sometimes it reads like this refers to carbon monoxide and dioxide, sometimes like there’s more stuff they aren’t specifying. And the part about the similarity to comets puzzles me.
    I guess what I really want to know is, is this hard, solid evidence that the stuff that life is made of is not unique to Earth? Or was that already done, and I missed it?

  21. Jonathan

    Also, I spotted NASA making a math error! (I’ll be strutting around for a week over this) The article always converts Celsius to Fahrenheit as absolute scales, but sometimes the figures are used in a relative sense, and thus the Fahrenheit conversions are too large by 32.

    What an exciting time!

  22. Jonathan: Carolyn Porco sent out an email with more specifics, but I wasn’t sure when I wrote the post if it was quotable. I emailed her back and she said yes, so I add to the post. Here’s what she wrote: “… it is now unambiguous that the jets emerging from the south polar fractures contain organic materials heavier than simple methane — acetylene, hydrogen cyanide, formaldehyde, propane, etc. — making the sub-surface sources of Enceladus’ dramatic geological activity beyond doubt rich in astrobiologically interesting materials.”

  23. andy

    Even if the traditional concept of the habitable zone gets ripped to shreds by the existence of subsurface oceans on outer icy worlds, it is still useful for extrasolar planet studies: it would be extremely difficult to detect a subsurface ocean on a world orbiting a star tens or hundreds of light years away. Detecting life in a subsurface ocean on an extrasolar planet or moon would be an even worse prospect, whereas Earthlike worlds offer atmospheric biosignatures which could in principle be detected.

  24. TheBlackCat

    Sometimes it reads like this refers to carbon monoxide and dioxide, sometimes like there’s more stuff they aren’t specifying.

    Carbon dioxide, carbon monoxide, cyanide, carbonic acid, carbonate, steel, and various other chemicals, although they contain carbon, are not considered “organic”. Organic molecules contain either carbon and hydrogen and/or more than one carbon atom attached to each other. They may contain many other atoms as well, but if they only contain one carbon atom and don’t contain any hydrogen they are generally not considered organic.

    I guess what I really want to know is, is this hard, solid evidence that the stuff that life is made of is not unique to Earth? Or was that already done, and I missed it?

    Yeah, it was done. What is new is that these molecules exist in large amounts alongside liquid water in a temperature range where life similar to life on Earth could reasonably be expected to survive (although whether it could form under those conditions is not clear).

  25. @ brad: Cute 2001 reference.

    Has it occurred to anyone that maybe we’re annoying the Enchaladans and those “plumes” are actually their attempts to shoot down the Cassini probe? Why am I the only one who worries about these things?

  26. Stripe

    So what are the odds of a sample return mission through those plumes within our lifetimes?

  27. asknot

    jeremy, it looks like you might have called it.

    http://www.msnbc.msn.com/id/23813470/

    At least they say “Seeds of life. . . ” instead of just “Life”

  28. Jonathan

    Thank you very much for answering my questions. (And pointing out my assumption, natch)

    Can’t wait to see what the next pass brings us. Of course, if Lugosi’s right, the Enchaladans’ll have better aim this time…

  29. Changcho

    I once read an interview with Freeman Dyson (I think it was on Wired mag.) where he suggested we should look for freeze-dried ‘fish’ orbiting Jupiter at roughly the distance of Europa. Now it seems we should look for these freeze-dried ‘Dyson-fishes’ around Saturn too. Hey, maybe that’s what the E-ring is made of ;-)

  30. Azrael

    I’d like to point out the similarity between the end of the 2001 saga, 3001: Oddessey’s End (or whatever it was called, eludes me for the moment), where our Lord and Saviour, Arthur Clarke, prophecised the organic-compound soup that the oceans of Europa were made of, and he prophecised it ages ago.

    The king is dead, long live his legacy.

  31. MandyDax

    @jeremy and asknot:

    That subheadline reads “Water spewing from Enceladus is gushing with organic material,” and all I could think was redacting jeremy’s prediction to read “OMG LIFE IN SPACE SPEW SPEW SPEW!”

    I love how we’re always finding stuff that we weren’t expecting out there. It’s really amazing. I always think of these lines from Hamlet:

    There are more things in heaven and earth, Horatio,
    Than are dreamt of in your philosophy.

    and of course Sagan:

    In some respects, science has far surpassed religion in delivering awe. How is it that hardly any major religion has looked at science and concluded, “This is better than we thought! The Universe is much bigger than our prophets said, grander, more subtle, more elegant. God must be even greater than we dreamed”?

    :) Thanks for pointing these things out, BA. I’m in childlike wonderment at them.

  32. davidlpf

    I for one welcome our Enchaladan overlords.

  33. dave

    The standard explanation for Europa’s (and Ganymde’s) water is tidal heating.

    Ok thanks, that explains it partially – but why is so much water ice there to begin with? I think I remember reading that Europa has even more water than Earth.

  34. Changcho beat me to the punch but I was going to mention the possibility of the probe being taken out as it dives through a plume by what would later be compared to a frozen sardine. Or considering the low gravity a frozen jelly fish.

  35. What’s the possibility of the organic compounds not be so much the building blocks of life but the fecal matter of life?

  36. davidlpf

    Maybe the moon is passing gas.

    MandyDax completely agree with you.

  37. Torbjörn Larsson, OM

    Water and organics – I think I will tap up a beer and contemplate that brew.

    “A completely unexpected surprise is that the chemistry of Enceladus, what’s coming out from inside, resembles that of a comet,”

    Damn, I knew it was too good to be true. Probably too complex and perhaps too pristine to be products of existing life. And uncertain life time for the phenomena.

    Ah well, it is a start, with great implications. And it is here to sample, right now! Cassini outdoes itself again.

  38. Will

    @dave
    I suspect Europa and Enceladus recieved their water from the same source as Earth: the universe. Eons of meteorites will deliver oceans to any planet that can support them, I would think…

  39. Torbjörn Larsson, OM

    No amount of evidence will ever convince the ID people that they’re wrong, as their belief are founded on religious conviction. They take pride from the fact that they are willing to believe such things on faith alone,

    Frankly I find it doubtful. If they were using those ‘fact-based science’ argument solely for the purpose to convince others, they would be much better on it.

    Instead they form a very primitive and totally distorted picture of science based on philosophy compatible with theology and analogy. And I think they do so, because most IDCers are really YECers that need ‘facts’ compatible with dogma to believe.

    As an example, over at Richard Dawkins net I discussed with an YEC priest that become upset over this. I noted that a religion without conflict with data (but not compatible with rationality) would be based on faith. (Essentially becoming as PZ Myers described it, “a hobby like knitting”.) He claimed roughly that I made a ridiculous proposition, he couldn’t see how (his) belief could be founded on anything else but facts.

    Of course, plural of anecdote is not data.

  40. Folcrom

    Someone mentioned the “goldilocks” zone will need to be expanded.
    Not so.

    The so called “goldilocks” zone relates one to one with the Thermally Habitable Zone, ie THZ.

    What Enceladus is, is another example of the possibilities of life, based upon what I call the “Europa analogy”.

    Tidal forces between gas giants and their moons can create sub-surface liquid water oceans. Jupiters moons Europa, Ganymede and Callisto could all have sub-surface oceans of H20. Saturn’s moons Enceladus and Titan could also have sub-surface oceans of H20. These hyperthetical sub-surface oceans, may have (over the eons) developed some form of life. This is yet to be seen. Simply put we don’t know yet. I’m hoping we’ll find out some time soon.

    If however, it pans out to be true, there would be huge implications. Life would no longer be limited to a THZ to exist. Europa analogues could exist almost anywhere in the universe. Gas Giant planets, Red Dwarf stars, Brown dwarfs and even rogue Gas Giants, could all harbor Europa Analogues. Life could be endemic in the universe. It opens up huge possibilities.

    Another possibility, perhaps not yet considered. Stars may have two THZs. One for water, ie our Earth is a good example sitting where it is in Sols THZ for H20.

    However, what about a THZ for Ethane/Methane?
    Could life as we “dont” know it, exist on Titan?
    Could Titan be sitting in the middle of Sol’s THZ for Ethane/Methane?

    Final thought (for the BAD Astronomer).
    If life was found to exist on or in Mars, Europa, Ganymede, Caliisto, Enceladus and Titan (in addition to the Earth), how would that affect the Drake Equation?

    Just some thoughts.

    Folcrom.

  41. Buzz Parsec

    Dave –

    Water is one of the most common chemical compounds in the universe,
    possibly the most common compound consisting of more than one element. (H2 is certainly more plentiful. Maybe methane and CO2 or ammonia are as well. That’s about it.) Comets, KBOs and Oort cloud objects consist mostly of water. So even a planet or moon that was too small to hold on to gaseous water and too hot for it to remain solid could acquire loads of water from comets after it had formed. But Enceladus is too far from the Sun for ice to melt just from solar heating, so any water it started with is probably mostly still there. (AFAIK, Saturn’s rings are still thought to be mostly water ice, unless Cassini has disproved this so there is lots of water near Saturn.)

  42. Rock

    While water certainly seems necessary for “life as we know it”, ice is actually an interesting possible environment for creating new forms of life. Experiments by Stanley Miller (yes that Stanley Miller) suggest that even on earth ice fields may have been a preferred environment for the formation of life. The implications for icy moons is obvious.

    See this article for some background:

    http://discovermagazine.com/2008/feb/did-life-evolve-in-ice/article_view?b_start:int=1&-C=

  43. Lugosi, calling them Enchaladans is full of win.

  44. Thomas

    So, this moon hasn’t cooled after billions of years? Isn’t that rather problematic? The focus on possible life is fun and all, but I think we’re skipping out on important work and discussion and going straight to play time.

    So, what could possibly allow this to be???

  45. Pat

    Thomas: The organic compounds? The propane? It’s probably got plenty of antifreeze…

  46. Dave,

    There are a number of light elements in condensing protoplanetary nebulae. Because of the thermal structure of the accretion disk (hotter closer to the sun), there is an “ice line” at about 4 AUs outside which the bodies that condense are as likely to incorporate volatiles like water ice as rock. Thus Mercury is mostly rock and metal, but Ganymede, which is about the same size, is about half water (and perhaps ammonia) ice. Satellites of the giant planets are all likely to incorporate large amounts of volatiles.

  47. Tom

    Gopher and Gary F got me thinking that a flagship mission may not be necessary. A flyby mission a la Genesis or Stardust could capture the materials and bring them back to Earth. The orbital mechanics would be a mess, but it should be feasible. Power requirements are an issue, but you wouldn’t need much power that far out.

    Hmmm…

  48. Thomas

    Johh Spencer has this to say. He rules out the likely candidates and basically is left just wildly guessing. It doesn’t make sense.

    Read Here.

  49. The BA wrote:
    “We don’t know how life started on Earth, but it’s a good guess that an ocean thick with organic compounds was involved at some point.”

    Well, well, well. This is quit an admission. I have been following the posts on this blog for a long time now and I got the impression that many of the people posting here seem to know the answer to this namely the spontaneous start to life from an organic soup.

    I am also amaged how many of you use ” OMG” even though you do not believe in God

    Philip

  50. Regarding a mission to Enceladus ESA has recently selected TandEM has one of the final candidates for a large mission to the OSS to be launched between 2015-2025…and this mission includes landers… ;-)

    Guess this news will weight a final decision…

    I made a special about TandEM not long ago at spacEurope.
    If you guys want to have a look:
    TandEM Overview: http://spaceurope.blogspot.com/2007/10/in-meeting-held-on-17-and-18-october.html

    Science Objectives: http://spaceurope.blogspot.com/2007/11/as-promised-and-after-general-overview.html

    Payload: http://spaceurope.blogspot.com/2008/01/after-long-time-since-last-chapter-ill.html

    Latest status report (January 24): http://spaceurope.blogspot.com/2008/01/as-soon-as-it-was-possible-here-it-is.html

    I’m all for it! :-)

  51. Theron

    Phillip:

    “Don’t know” does not mean “God did it.” It means “we need more data.”

  52. MaDeR

    “God did it” == “We does not know, we don’t want to know, we want to be blind and stupid”.

  53. John H

    I am surprised that there is no mention of either ammonia or nitrogen being found in the jets. I would not have expected all of the nitrogen present in the jets to be contained solely in organic compounds.

  54. John Phillips, FCD

    Phillip, a lot of us atheists use phrases that contain god, Jesus or similar, that might be construed as having religious significance, especially when we need an exclamation or a curse. However, why would this surprise you? After all, even if many here are atheists, most live in a culture were mention of god and god belief is all around us and is part of the cultural baggage of our societies. Additionally, many of us were originally xians, even if only culturally, before we woke up and smelled the coffee. Thus it no surprise that we still use such words and phrases. Unless of course you expect us to censor what we say simply to avoid believers getting pedantic with us. Or is it that we are not allowed to use those words or phrases because we are no longer believers.

  55. Bruce G.

    “Makes me wonder if we will not soon be able to find “real” extraterrestrial life forms and shut up “CR” & “ID” people for good!!. On the other hand , they would not be convinced by anything revealed by scientists . At most they would “pray for guidance”. ”

    Actually, belief in life on other planets is not at all incompatible with Christianity. If God can do on one planet, he/she/it can do it on every planet. See the arch-apologist C.S. Lewis’ space trilogy “Out of the Silent Planet.”

  56. Torbjörn Larsson, OM

    Jupiters moons Europa, Ganymede and Callisto could all have sub-surface oceans of H20. Saturn’s moons Enceladus and Titan could also have sub-surface oceans of H20.

    IIRC, The Planetary Society published an article detailing ~ 10 candidates for subsurface liquid water moons a few years back. YMMV.

    @ Philip:

    many of the people posting here seem to know the answer to this namely the spontaneous start to life from an organic soup.

    No, it is generally acknowledged that it is an open question how it started. That life started is pretty established. :-P

    I am also amaged how many of you use ” OMG” even though you do not believe in God

    Now you are equivocating between science and atheism. They are different phenomena.

  57. I’m slightly disappointed that the first illustration didn’t have the word “Baby” floating in the subsurface water, beneath the “Ice Ice”.

  58. Is their leader the Big Enchalada?

  59. andy

    OMG=Oh My Gosh, surely? :-)

  60. Russell

    It is possible that bacteria (or archaea) that ride outward on the jets would not necessarily ‘die’ as we identify death, but rather exist in a super-stasis. It is becoming more recognized that extremeophile prokaryotes on Earth can live in super-stasis for incredibly long periods of time. (This would extend the ‘Goldilocks Zone’ into the fourth dimension, eh?)
    Regardless, the latest finds are truly extraordinary and shows that the science team can still pull off amazing feats if supported by the government. Thanks for the nice synopsis.

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