Could there be Life on Jupiter and Saturn’s Moons?

The ongoing search for the existence of life that doesn’t call the Earth ‘home’ could potentially find that life right here in our own Solar System. There is considerable debate about whether evidence for that life has already been found on Mars, but astronomers might do well to look at other, more exotic locations in our neighborhood.

At the recent meeting of the American Geophysical Union in San Fransisco, Francis Nimmo, who is a professor of Earth and planetary sciences at UC Santa Cruz, said that the conditions on Saturn’s moon Enceladus, and Jupiter’s moon Europa may be just right to harbor life.

Nimmo said, “Liquid water is the one requirement for life that everyone can agree on.” The water underneath the icy crusts of Enceladus and Europa may just be teeming with alien fish and algae, or more basic forms of life such as bacteria.

Nimmo is one of a long list of scientists speculating on the existence of life on these watery moons. A discovery of any life form originating from a planet other than the Earth “would be the scientific discovery of the millennium,” Nimmo said. And even saying that is an understatement.

If life were able to exist in the watery oceans of the moons around Saturn and Jupiter, Nimmo said, it would mean that the ‘habitable zone’ around a star would extend much further out than previously thought, to moons that orbit large gas giants in other systems around faraway stars.

The possible ocean under the surface of Enceladus may receives its heat from the tidal forces of Saturn. That is, if there is an ocean under the surface of Enceladus, as that topic is still somewhat debated among astronomers. The constant tug of Saturn’s gravitational pull may stretch the interior of the planet enough to heat the water below the crust of ice, which is estimated to vary in thickness between 25km to 45km. Geysers of frozen water forced out of crack on Enceladus’ surface have been observed by the Cassini mission, and the craft has even flown through the plume of one of these jets.

Here’s a video of Carolyn Porco, who leads the imaging team on the Cassini mission, talking about the potential for life inside the moon, and some of the discoveries made by Cassini so far:

Evidence for the ocean under Europa’s icy skin comes from the Galileo mission, which passed by the moon in 2000 and took measurements of the moon’s magnetic field. Variations in the magnetic field have led astronomers to believe there is a vast ocean of water under the surface, leading to natural suppositions about the potential of its habitability.

Europa’s ocean is heated much in the same way as that of Enceladus: both moons have an eccentric orbit around their much more massive planets, and this orbit causes a shift in the way the planet tugs on their interiors, causing friction in the cores which in turn heats them up.

The core and surface of these moons both are possible sources of chemicals that are necessary for life to form. Impacts from comets can leave molecules on the surface, and light from the Sun breaks down compounds as well. Organic molecules and minerals may originate in the cores of the moons, streaming out into the watery ‘mantle’. Such nutrients could potentially support small communities of exotic bacteria like those seen around hydrothermal vents here on Earth.

Of course, just because these moons are habitable doesn’t mean that life exists there, as Nimmo and other planetary scientists are quick to point out. Cassini may still provide evidence of life on Enceladus, as the data from this last flyby of the plumes is still being analyzed. Future missions to Europa, such as the proposed ‘interplanetary submarine‘, may also give us an answer to the question of life’s existence elsewhere, and of course the quest continues for a mission to Mars that will finally give us some idea of its habitability now or in the past.

Until the data comes back from these missions, though, we’ll still have to wait and speculate.

Source: UC Santa Cruz press release

20 Replies to “Could there be Life on Jupiter and Saturn’s Moons?”

  1. “So what? I couldn’t relate to some bacteria.”

    Wow. That is an amazingly short-sighted statement. Think about the implications for the likelihood and quantity of life throughout the universe if we discover even just bacteria-like species elsewhere in our solar system.

  2. Once again I beg the scientific community to tell me why they aren’t more interested in the possibilities of life on Jupiter and Saturn themselves!!! Just the colors of Jupiter and the intracacies of it’s atmosphere would tell me there’s life there. Do vou think there isn’t atleast atmospheric organisms? You know there’s water–probably 500 mile deep oceans of it with floating islands to boot. And a grand magnetosphere to protect it from radiation. Forget the moons—Jupiter is the place to put a low cost balloon orbiter–WITH CAMERAS!!–if your searching for life. Someone tell me where I’m wrong on this—as I have previously expounded upon before. Ms. Porco—won’t you consider the possibilities that this huge planet harbors abundant life that has probably well modified the chemistry and stratification of it’s layers. I think it would be highly improbable for Jupiter not to have some life.

  3. BlueAmbersol: “So what? I couldn’t relate to some bacteria.”

    Underlings replies: “Wow. That is an amazingly short-sighted statement.”

    I’ll second that. The detection of living organisms, however primitive, elsewhere in the Solar System by itself would be one of the greatest scientific discoveries in human history.

    But even more astonishing would be the determination of whether such organisms used something like DNA or RNA to pass on hereditary traits, or if some heretofore unknown mechanism was involved. Determining THAT would raise a whole slew of new questions and have profound implications for our understanding of evolution and biology.

    With today’s technology, how difficult could a sample-return mission to Europa be? It wouldn’t even have to consist of a submersible, just some way of carrying home a little bit of that reddish ice that’s found around the cracks in Europa’s crust. Imagine how much a good lab analysis of such a sample back on Earth would determine!


  4. @ Kemp Woods

    I think there is a general acknowledgement that there is chemistry and energy enough in the atmosphere of planets such as Jupiter and Saturn. I think the objections to exploring are more practical…

    So far, all of our planetary explorers have been remote cameras or landers. We have not yet made a remote that floats in the atmosphere. There are very few craft like this even on Earth. There have been calls to make something that works on Titan, or Venus, or even Mars. If we have done this, we might be more confident at tackling the more extreme environments of Jupiter and Saturn.

    If we are looking for life (and we are looking for it, but we are also just looking too) then there is a temptation to start looking where life as we know it is likely to exist. Organic life is an ordering process: it needs energy and chemistry to run, but it also needs somewhere quiet to make careful copies of itself without being disturbed. It seems possible that the upper atmospheres of the gas giants have too much ionization, so the processes that break up large molecules outmatch the processes that create them. Deeper down, there may be more hospitable environments, but we have very little direct knowledge of what is down there yet.

    There are bacteria that live wholly in the atmosphere on earth. In the early stages, it seems likely that life needed a surface for materials to collect and become concentrated, but we don’t know this for sure. I am sure a Jovian atmospheric rover is on the list of things to do: it just hasn’t come to the top yet.

  5. I have some skepticism over the prospects for life under the ice of these moons. However, it is plausible. In looking at planetary bodies there are a number of important things which should be considered. These are temperature, energy flow and chemistry.

    Warm temperatures are likely optimal, though that might be geo-parochialism. Cold temperatures might possibly hold life and very hot temperatures are unlikely to. Heat is a form of energy in a disordered state as entropy, and highly ordered structures are not likely. This is why I think the superheated mega-ocean planet just found is probably not biologically active. Clearly the lava planet Rocot (sp) is not biologically active. Very cold or cryogenic temperatures are unlikely to host life, but that not impossible. Ice that is not too cold will have cracking where liquid forms might exist, even if transiently. Mars has evidence of this. So cold life is possible, and in cold conditions it might just operate on a much slower time frame.

    The other is energy flow. An environment which is comparable to Earth’s temperature, but which has no flow of energy will not host life. An energy source is needed, whether that is light or heat, and you also need a cold bath where energy flows into. This is what runs any heat engine, which the ATP –> ADP + P_i mechanism of metabolism is an example of. For every optical photon which reaches the Earth there are 20 photons in the infrared band which leave the Earth, at a much larger wavelength and more disordered. These photons escape into outer space, which serves as our cold bath.

    We might imagine a planet orbiting around where Mars is, which also has a very thick atmosphere. It might then have surface temperatures comparable to Earth, but energy flow would be much slower. So life might be less probable on a planet situated in a Mars orbit around a star comparable to the sun.

    The other is chemistry. I tend to be a carbon centrist, though silicon life is maybe not impossible. However silicon most readily forms crystalline structures, called rocks, instead of long chain molecules. I have a hard time seeing rocks as living systems. There also have to be the appropriate elements which chemically bind to the backbone element, which is carbon or maybe silicon, and these must include hydrogen, nitrogen, oxygen and so forth. In fact biology here involves over 70 of the elements on the periodic table. And if carbon is the only backbone it is likely that water is required, and it must exist in a liquid form or at least enter that phase periodically, such as small water pockets in warmer ice. This also most likely requires an atmosphere as well. I doubt the moon has life on it, unless it is some silicon life form tunneling below the surface —- unlikely, but not impossible until ruled out.


  6. Bottom line?______ The whole universe is a living being that some might call GOD.

    Donno if you saw it, but the Indian lunar probe apparently saw combination’s of organic molecules which indicate as much on our moon!? Why should we be surprised? Think about the extremeophiles living in the Earth’s crust… WHAT? Critters that eat methane and excrete metals? How about critters that consume other forms of energy in the cryogenic range and exist beyond our physiological awareness?

    We are expanding our ability to conceive of that possibility as we plumb the depths of our solar system… a primer?

  7. Bottom line? _____ Most of the universe is a stone dead waste of space, that some may call a universe. (o.O)

    It is the biospheres dwelling in it that fuel our interest here.

    Btw, nice analysis, LBC!

  8. I understand that the basic idea of life other than our own on earth is amazing in its own right, but deep down aren’t we all really looking for ET? Intelligent life similar to us (hopefully not exactly like us 😉 , so we know we are not alone. Bacteria is all well and good but i’d still only help to wider our horizons on potential life sustaining objects.

  9. Mr Youngie,

    What would really captivate the world over is TV broadcasts from an ET civilization. But the chances are for all intents and purposes none.

  10. “But the chances are for all intents and purposes none.”

    That’s my guess anyway. The broader the range you consider from earth, to increase the chances of a technically advanced civilization, the weaker any radio broadcast will be for us to detect. I’m not even sure what our detection distance limit is given our receivers for broadcasts that are comparable for what we’ve been putting out.

  11. That ET signal that we are searching for? It past us by 100 years ago as a last gasp distress call from a dying civilization that failed to heed the warning signs of its dying planet.

  12. That ET signal that we are searching for? The last one passed us by 100 years ago as a last gasp distress call from a dying civilization that failed to heed the warnings of its climate scientists.

  13. Sorry for the double post. Didn’t think the 1st one made it. 2nd one corrected “past” and makes the point better. Sorry for the political implication; Cope-15 made me do it.

  14. To be honest I think there is about a 50% chance of life on Mars. I give these Jovian moons about 10-20% chance of having life. Yet in the case of Mars there is little evidence of complex life. There certainly are not Martian beings building canals and the life. There is no evidence of so much as a blade of grass, or some martian analogue of a plant, or any sort of “bug.” So while there might be life on some of these extreme environments, they are probably not terribly complex, such as found here with worms, daisies, trees, birds etc.


  15. Instead of searching for life which may or may not exist, complex or not, woulden’t it be better to look for planets which we know are near perfect or certainly good enough to support life? Ok they wont be easy to find but atleast that way it would speed up the process of understanding life in space. The small bacteria can wait in line behind the complex organisms in my opinion.

  16. Fifteen years ago most of us thought no other star systems had even planets, that life had no chance beyond Mars, that life on Earth was fragile and now these days our views are the complete opposite.

    I would wager that life is very common, its not going to be waving a big flag saying we are here (Martian Canal style), we have to get out there and find it.

    How many lifeforms are on this planet that we have yet to find? How many kinds of bacteria are on your hand right now that are unknown to us? Life is out there waiting to be discovered by us.

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