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Saturn's Moon Enceladus Has an Atmosphere

Dimentox writes "The Mercury News reports that the international Cassini spacecraft has discovered that Saturn's moon Enceladus has a significant atmosphere, NASA said Wednesday. The icy moon's atmosphere may be created by volcanism, geysers or gases escaping from the surface or the interior, the space agency's Jet Propulsion Laboratory said. Excluding Saturn's giant moon Titan, which was already known to have an atmosphere, it's the first discovery of an atmosphere on one of the more than 30 moons that orbit the ringed planet."

47 of 224 comments (clear)

  1. Re:Well, for one thing by theparanoidcynic · · Score: 3, Insightful

    So? Mars has 2/3 less gravity than the Earth, and it has an atmosphere of sorts.

    The link doesn't seem to say, but anyone know how thick the atmosphere is, or what it's made of?

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  2. Enceladus has atmosphere... by Anonymous Coward · · Score: 5, Funny

    but, alas, lacks ambiance. We give it one star.

    1. Re:Enceladus has atmosphere... by Rauser · · Score: 2, Funny

      It's sadly lacking in warmth as well.

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  3. Second First by LakeSolon · · Score: 5, Funny

    Excluding Saturn's giant moon Titan, which was already known to have an atmosphere, it's the first discovery of an atmosphere...

    Excluding the first it's the first? We have a word for that. "Second".

    ~Lake

    1. Re:Second First by aussie_a · · Score: 4, Insightful

      Excluding the first it's the first? We have a word for that. "Second".

      People tend to think that the second isn't important, so they like to make stuff the first. It is the first that this probe has discovered. Titan having an atmosphere has been known for some time, this is the first discovery of one of Saturn's moons having an atmosphere in quite a while. This is also what the article meant.

      So while your comment has been marked interesting, it's really not. It's pedantic more then anything.

    2. Re:Second First by Anonymous Coward · · Score: 3, Insightful

      It's a lame excuse to make it sound like it's more important than it is. It's like "Columbus was the first to discover the Americas, excluding the vikings and the people already living there."

      It's an attempt to give credit where it isn't due and to inflate the importance of an event.

    3. Re:Second First by Anonymous Coward · · Score: 2, Funny

      The word you want is spelt "pedantist".

  4. Re:That's no moon! by rob_levine · · Score: 2, Funny

    I have a very bad feeling about this...

  5. lift a cheek... by caino59 · · Score: 2, Funny

    The icy moon's atmosphere may be created by volcanism, geysers or gases escaping from the surface or the interior, the space agency's Jet Propulsion Laboratory said.

    Gases escaping?

    It's the GNOMES!

  6. Re:Well, for one thing by jbrader · · Score: 3, Interesting
    Just a guess based on what I know about Titan, but the atmosphere is probably composed of methane and other nasty hydrocarbons.

    As to how thick it is, since it wasn't detected until we got "close" to it, it's probably quite a bit thinner than Titan's atmosphere.

    Again,even though this is the field I'm in school for right now, I'm pulling all this out of my butt. So usue the usual grain of salt.

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  7. Nice discovery for the bad news by nsasch · · Score: 4, Insightful

    It's really great news for the mission especially after the wind measurement tool didn't function properly at first. 15 more years, and there'll be a space craft at this moon.

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    1. Re:Nice discovery for the bad news by aussie_a · · Score: 4, Insightful

      Not necessarily. Is the surface obscured like Titan's? If not, then there isn't as much incentive. I think Europa would be much more important then this moon. Why not send a probe to Triton? After all, Triton may have been liquid for billions of years. It's also possible that Triton may have once harbored life (due to it once having liquid), and that if it did, such life would be COMPLETELY different to Earth's. That sounds more significant then Enceladus.

      Why this moon? Just because it's in the news today, doesn't mean it will be all that important tomorrow. Neptune isn't an impossible goal. We can send probes to places other then Saturn.

    2. Re:Nice discovery for the bad news by Rei · · Score: 4, Informative

      Not likely. The next craft to Saturn is undoubtedly going straight to Titan (the highest priority target in the Saturnian system - hence, Huygens), and that will take 10-15 years between design, construction, launch, and transit (unfortunately, Jupiter won't be available to assist spacecraft to Saturn again for a while). Without Jupiter, you either need a JIMO-style nuclear electric propulsion mission (expensive - JIMO was cancelled, darn them!), or need to accept 100-200kg payload, so don't expect many craft, either.

      Perhaps in a 20-30 year timeframe, but for now the payloads are just too small for the investment to justify a trip to Enceladus when we could always go to Europa if we want to study an icy moon with subsurface liquids.

      --
      "Here's a fun fact: the moon has turned to blood!" -- Newscaster, "Jesus Christ Supercop"
    3. Re:Nice discovery for the bad news by Rei · · Score: 3, Interesting

      The liquids on Triton are *nitrogen* (and we have no clue how much there is; it's atmosphere very thin, though). I wouldn't rule out life on Titan, but Triton is even colder, and unlike Titan we have no evidence of any organic chemistry there. Of all of the places in the solar system, why did you pick Triton?

      I mean, I can understand people arguing for life on Mars (it had past water, it's huge, lots of solar energy, etc). I can understand people arguing for life on Europa - it has an undersea, tidal heating as an energy source, etc. I can understand people arguing for life on Titan - it has extensive organic chemistry occurring in its upper atmosphere, has a known fluid (even if nonpolar) on its surface, seems to be a geologically active world (and thus has internal heat), etc. I could even understand speculation about life on Io, it being such an energetic world. But Triton? You might as well pick any body in the solar system. Heck, I'd give there better odds of having life in a gas giant than Triton. :P

      --
      "Here's a fun fact: the moon has turned to blood!" -- Newscaster, "Jesus Christ Supercop"
  8. It would be nice to link to the actual article by PxM · · Score: 4, Informative

    Link It should be noted that this isn't an atmosphere in the common sense. The air is continually created and lost due to internal sources and weak gravity.

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    Wired article as proof

    1. Re:It would be nice to link to the actual article by Surazal · · Score: 2, Interesting

      (I RTFA, but couldn't find any info about atmosphere composition... strange, if they detected it, you'd think they'd have a clue what it consisted of too)

      The two articles I've read on this subject both indicate the atmosphere is water vapor.

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  9. Excluding.... by jbum · · Score: 4, Funny

    Excluding the more than 30 moons that orbit the ringed planet, it's the first discovery of a moon orbiting the ringed planet!

  10. significant? by Anonymous Coward · · Score: 3, Interesting

    *Any* atmosphere on a sub-500km wide moon would be significant. I'm looking forward to a more complete report as more information comes in.

    Why am I suddenly hungry for Mexican food?

  11. I wonder what else we're missing? by cubicle_cowboy · · Score: 4, Insightful

    I know this argument is getting old, but this is a good example why we should be spending more money on unmanned probes instead of high-cost, low-science manned missions like the space station. There's little reason at the moment to spend large sums of taxpayer cash on things that provide little benefit. Imagine all the probes we could be sending instead. A whole fleet of Cassinis, Voyagers, and Mars Rovers combing the solar system! Let the private industry (ie. the guys with Scaled Composites and maybe even Virgin ;) take the baton on manned space flight. Hopefully the private industry will find ways to lower the costs so that when we finally need people in space, it'll be practical.

    1. Re:I wonder what else we're missing? by QuantumG · · Score: 4, Insightful
      and all the research that needs to be done to make living in space actually possible is going to happen where? Frankly, if we're ever going to go to Mars, we need to learn how to live in space for extended periods of time. Even with our best propulsion systems it will take at least 18 months to get to Mars. During that time astronauts need to live in the ship. That makes your space ship a space station. So how in the world are we supposed to build a self sustaining space station that we can fly to another planet if we can't even sustain one in low earth orbit?

      Excluding the creation of some buck rodgers form of space propulsion the ISS is the best bet we've got for space colonisation.

      --
      How we know is more important than what we know.
    2. Re:I wonder what else we're missing? by chialea · · Score: 2, Informative

      > Also, we've already kept people in space for long periods of time (or at least as long as long as a trip to Mars would hopefully take)

      The longest stay in space seems to be 14 months (see http://news.bbc.co.uk/1/hi/sci/tech/374456.stm), which is not quite enough for most trips. In addition, I seem to remember that people were pretty screwed up afterward. We need to either: a) figure out how to keep people up there that long and have them be useful in .38g on the other end or b) build a good rotating space station.

      It's my guess that we'll end up with option (b), just because of the bone decalcification effects, neglecting the cardiac, psychological, muscluar, and other physiological effects. I'm not aware of any sufficiently detailed research on the subject, however.

      Lea

    3. Re:I wonder what else we're missing? by QuantumG · · Score: 2, Informative

      A lot more than $100 billion has gone into propulsion research over the years. We simply don't know how to make better rockets. We have some ideas. Like fusion rockets. But they require breakthroughs (like fusion) for which we've spent even more money on.

      --
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  12. How unique is this? by jerkychew · · Score: 3, Interesting

    Please bear with me, as I never paid any attention to astronomy-related stuff. I'm just curious as to how many other planets/ moons/ celestial bodies out there are known to have an atmosphere? Is this a really big deal, or is it a relatively common occurance?

    1. Re:How unique is this? by Anonymous Coward · · Score: 2, Informative

      Well, it'd be the 2nd moon ever with an atmosphere, and the 7th body in total with one (although Pluto probably has one, but that hasn't been proven).

    2. Re:How unique is this? by l810c · · Score: 2, Informative
      Could you name the ones you know of?

      I've done some googling and have come across conflicting answers. One site lists only Titan as having an Dense atmosphere. Another lists Io, Europa and Triton with Tenuous(require regeneration) atmospheres as well. This new moon would seem to fall in that category.

      And the planets?
      Venus, Earth, Mars and maybe Pluto?

    3. Re:How unique is this? by Wyatt+Earp · · Score: 2, Informative

      All the planets have an atmosphere of some sort. Mercury is trace, but there is something, a little something.

      Venus to Pluto have atmo, so there are 8 bodies and Io, Callisto, Ganymede, Titan, Enceladus and Triton.

    4. Re:How unique is this? by jd · · Score: 4, Interesting
      The Gas planets have atmospheres. Well, if they didn't, they'd be a lot smaller.


      Europa has H2O in both ice and liquid forms, which is horribly unlikely at near-zero pressure, which means it almost definitely has an atmosphere.


      Any comet can be considered as having an atmosphere, whilst it is close to the sun and being frazzled. However, I think there are some who consider that cheating.


      Any object close to (or larger than) the size of Mars is going to have an atmosphere, provided at least one of the following conditions is met:


      • After the planet formed there was a liquid core capable of generating and sustaining geological activity such as volcanos, geothermal vents, etc.
      • Gasses or liquids start on the surface where the rate of loss into space is equal to or exceeded by the rate of replenishment. (Replenishment may include geological activity, meteorites containing suitable compounds, etc.)
      • After the planet formed, it encountered an atmosphere (most likely from a comet that didn't quite hit) that it could then capture and retain.
      • After the planet formed, it encountered the necessary compounds by actual impacts from cometary fragments, meteorites, etc.


      The gas giants can form either from a cloud that coalesces as per a rock planet, but never actually becomes solid, OR when a very large rock planet sweeps enough lighter material to build an atmosphere around it. Jupiter is now thought to be of the first kind, Saturn of the latter.


      There may be other ways an atmosphere can form, but these would seem to be a good start on a list.

      How can an atmosphere NOT form on a planet?

      • It started off with one, but
        • It escaped faster than it could be replenished (planetary spin too high, insufficient gravity and/or too high a temperature)
        • The source material or driving force used to replenish it ran out
        • It froze solid
        • It chemically reacted with something to become part of the surface
      • It didn't start with one and
        • There are no processes to generate one internally
        • There is nothing on the surface suitable and at the right temperature
        • It has never encountered suitable frozen material in cometary fragments that could supply one
        • It has never encountered free-floating gas molecules in sufficient quantity AND that is sufficiently massive to be captured and stay on the planet AND isn't moving fast enough relative to the planet to escape.

      I don't know what the odds are for any of these, but it would seem reasonable to suppose that 20-30% of all moons will have some sort of atmosphere, and maybe 60-80% of all planets do. We've not found many small extrasolar planets, so we can't tell from that. However, if you go by mechanisms, those percentages feel reasonable enough.

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  13. Re:Where's the article? by aussie_a · · Score: 5, Informative

    It's right here. Why that page wasn't linked to in the first place is beyond me.

  14. Re:Well, for one thing by Rei · · Score: 5, Interesting

    The link says that it's made of water vapor, but doesn't give a density. It's interesting, because Europa (a seemingly similar moon - it has the same sort of wrinkled surface) has a *very* tenative (about 1/100,000,000,000th of 1 atmosphere) water vapor and oxygen atmosphere from the sublimation of ice and the breakdown of water from interaction with the solar wind.

    I'd imagine that this atmosphere is notably more significant than Europa's, or they wouldn't have described it as they did. And, with less solar energy at these distances, they're speculating that the source is from internal heating causing water geysers. That's really rather fascinating, when you think of it - now we know of another moon with a likely subsurface sea. The moon is a lot smaller than Europa, but it probably has more significant internal heating for its size.

    Plus, the saturnian system has a lot of interesting organics - Titan is virtually a drifting mobile organic chemistry lab in its upper atmosphere. Even neglecting Titan, there's the unknown dark organics on Iapetus, Phoebe, and in the rings, among other places.

    --
    "Here's a fun fact: the moon has turned to blood!" -- Newscaster, "Jesus Christ Supercop"
  15. Re:It's basically almost virtually the first one! by Anonymous Coward · · Score: 2, Funny

    After this person you're the first person who has mentioned that.

  16. All your base are belong to us? by Jugalator · · Score: 4, Funny

    The Mercury News reports that the international Cassini spacecraft has discovered that Saturn's moon Enceladus has a significant atmosphere, NASA said Wednesday.

    Not only that, but I bet there's an entire rebel base there as well!
    NASA should better send down a probe there to check it out.

    --
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    1. Re:All your base are belong to us? by Capt'n+Hector · · Score: 2, Funny

      That's no moon! It's a space station! (that's the other side.)

      --
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  17. Re:Well, for one thing by Rei · · Score: 3, Informative

    Oh, it's almost definitely not organics. Encladeus is the most reflective large body in the solar system; it has to be almost pure ice and "gasses" (probably a tiny amount of oxygen from disassociation of water, maybe a little nitrogen, etc). In all likelyhood, it is geysers of water and/or steam that are creating the atmosphere.

    --
    "Here's a fun fact: the moon has turned to blood!" -- Newscaster, "Jesus Christ Supercop"
  18. First? by IWannaBeAnAC · · Score: 3, Insightful
    Excluding Saturn's giant moon Titan, which was already known to have an atmosphere, it's the first discovery of an atmosphere on one of the more than 30 moons that orbit the ringed planet.

    So, you really mean that it is the second moon of Saturn found to contain an atmosphere? Why not say just that?

  19. Re:Well, for one thing by Anonymous Coward · · Score: 2, Informative

    One of the passes was only 500km in height. Given that Enceladus is 500km in diameter, that leads me to think this is not a very thick atmosphere at all.

    For comparison, Titan's 1.5 bar atmosphere is over 500km in height, and Titan's gravity is something like 100x that of Enceladus.

  20. international? by minus_273 · · Score: 3, Insightful

    i know bashing the US is cool, but isn't this a NASA project paid for by the US tax payers?

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    1. Re:international? by BrianRaker · · Score: 4, Informative

      Actually, the Cassini project is a co-op by NASA and the ESA (European Space Agency).

      --
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  21. MMMM. Mexican Food! by levitater · · Score: 3, Funny

    Homer: Mmmmmm.... Moon Enchiladas.

    Comic Book Guy: For your information, my corpulent comrade, it's "Enceladus," who in Greek mythology was a giant who was defeated in battle and buried under Mount Etna by Athena.

  22. Re:That's no moon! by pyrrhonist · · Score: 4, Informative
    That's a space station!

    Wrong moon. You want Mimas.

    --
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  23. So. . . does that mean *I* have an atmosphere? by jafac · · Score: 3, Funny

    ...The icy moon's atmosphere may be created by ...gases escaping from ... the interior...

    That could describe a lot of people I know.

    --

    These are my friends, See how they glisten. See this one shine, how he smiles in the light.
  24. First Post! by psychgeek · · Score: 5, Funny

    Excluding the posts above, I *finally* have a first post.....

  25. The Mercury News? by Anonymous Coward · · Score: 2, Funny

    Shouldn't the Saturn News be reporting this?

  26. Mercury's atmosphere by zippthorne · · Score: 2, Interesting

    Is more like a few of those super-ball thingies bouncing around a really roomy tank. The particles don't even interract with each other: the most prevalent collision is by far the particles with the surface. In fact, there's some question about solar pressure 'blowing' away the atmosphere. (though it would be replenished by solar wind particles) On earth would be very difficult to get a vacuum of the quality of mercury's "atmosphere." calling it a trace is extremely generous.

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  27. International Cassini spacecraft? by i41Overlord · · Score: 2, Informative

    Cassini is NASA. ESA was the Huygens probe.

    If both NASA and the ESA want to share credit for the whole mission, fine, I'd go with that. But that didn't seem to be the attitude when the Huygens probe landed on Titan. When that happened, I recall the ESA being *very* specific that it was their probe- and their accomplishment, and not NASA's. I thought that was a bit rude. In other words they want to share partial credit for what isn't thiers, but they want to take total credit for what is theirs.

  28. It might. by jd · · Score: 4, Interesting
    If, under the surface, you have a cavern, or network of caverns, of sufficient size, which are 100% isolated from the primary atmosphere and where the composition of the air is non-trivially different, it would be possible to argue the case for Enceladus having two atmospheres.


    Alternatively, since gravity appears to be insufficient to hold the atmosphere in, if the northern hemisphere's atmosphere and southern hemisphere's atmosphere never interact (eg: there's nothing left of either by the time you reach the equator) then you could again argue that they should be considered distinct and not part of a single whole atmosphere.


    Of course, these are highly improbable, but this IS Slashdot.

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  29. Coincidentally... by serutan · · Score: 2, Funny

    Our sysadmin's cube also has an atmosphere created by gas escaping.

  30. Re:We need spinning space stations. by QuantumG · · Score: 4, Informative

    Just in case you actually care. The reason spinning space stations don't work is called coriolis acceleration. Basically spinning results in horizontal as well as vertical acceleration. The vertical is what you want. The horizonal is what disorients and makes astronauts sick. Now, if you happen to have a really really big wheel you can reduce the effects of coriolis acceleration but yeah, you need all that mass. One solution to this is to use a tether and spin a small station around a very very long axis (like kms). That's great an all but 1) it doesn't work in low earth orbit and 2) if the tether breaks you've got a nice uncontrollable projectile there. Then there's the actual problem of getting it spinning in the first place.

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