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Space Science

Titanic Saturn 97

barakn writes "Using the Crab Nebula as an x-ray source, scientists have observed Titan's x-ray shadow to get a preliminary estimate of the extent of its outer atmosphere. On the same page, another article discusses the possibility that the hydrocarbon seas of Titan bear waves, albeit slow-moving and widely spaced, 7 times higher than waves on Earth (additional wave links here, here, and here). And Cassini-Huygens has snapped a photo of Saturn showing "two small, faint dark spots" in the southern hemisphere (this link has convenient arrows pointing at them, or here). Cassini-Huygens will achieve Saturn orbit insertion on July 1st. Huygens will detach and enter Titan's atmosphere in January, 2005."
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Titanic Saturn

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  • by Teckla ( 630646 ) on Saturday April 03, 2004 @09:52AM (#8755314)

    Inquiring minds want to know: how does Titan keep its thick atmosphere in such low (15% of Earth) gravity?


    • by sploxx ( 622853 ) on Saturday April 03, 2004 @10:08AM (#8755370)
      Yes, that's a good question. IANAPS (planetary scientist) but studying physics and should be able to give you a rough answer:
      It's because titan is much farther away from the sun than earth and therefore much colder.

      The point at which the loss of atmosphere becomes significant is when a sizeable amount of the atmosphere's molecules have escape velocity due to their temperature. Maybe mars lost it's atmosphere that way.

      Try, e.g. "celestia" a free universe simulator to get a picture of the distances in the solar system.
      • I've read that because the size of Mars, it's internal core cooled down rather quickly. When this happend, the magnetic field dropped which left its atmosphere to be slowly erroded away by solarwind. Should Earths core solidify, I fear it too will face the same fate that Mars did.

        • Actually, IIRC, most astronomers now believe that the reason that mars doesn't have an atmosphere is because of a reverse runaway greenhouse effect.

          Mars is just far enough away from the sun that the CO2 from its atmosphere started to condense into the rocks and water (which was present at the time this was happening), this caused the temperature to lower, causing more CO2 to go away, lowering the temp and so on.
          This also explains why Venus has a thick hot atmosphere.
          You can find more if you google for it.
      • by Anonymous Coward
        The mass of the molecules is also involved. If the average kinetic energy of the molecules is of the order kT, a more massive molecule will have a lower average speed. The nitrogen molecules of earth's atmosphere are quite a bit more massive than hydrogen molecules, which I believe earth cannot hold onto for long periods of time.
      • Another governing factor is how susceptible the satellite is to solar wind. A magnetic field or extreme distance from the sun can reduce this. So, does Titan have a magnetic field, or just the distance helping out?
    • by Anonymous Coward
      Inquiring minds want to know: how does Titan keep its thick atmosphere in such low (15% of Earth) gravity?

      Titan is cold, its atmosphere's molecules slow and heavy.

      It possibly was ejected in its formative phase containing a lot of volatile elements which replenish it as it goes.

      It may participate in a gas torus cycle with Saturn where the atmosphere stripped by solar winds is fed into Saturn's orbit for potential later return to Titan.
    • It's because of the gas torus effect. When atmosphere leaks away from Titan, it's still in roughly the same orbit about Saturn. When a lot of the atmosphere has leaked into that same orbit, it builds up and starts to form a torus of gas around Titan's orbit which helps keep the moon's atmosphere replenished. It's the presence of Saturn which allows this effect; rather than just getting blown into interstellar space like atmosphere escaping from, say, Mars does, it goes around Saturn and more or less comes b
      • by CheshireCatCO ( 185193 ) on Saturday April 03, 2004 @01:41PM (#8756444) Homepage
        I don't know who told you that, but that's totally wrong. There's no way a significant fraction of the atmosphere would ever be re-accreted by the planet from a torus, first of all. (Io has a very distinct torus and its atmosphere is all by non-existant.)

        Second of all, we have yet to observe any Titan-torus, last I heard. (About two weeks ago, a comment made from one of the Cassini principle investigators.) If there's so much gas there, why can't we see it?

        Finally, the reason Titan can hold a thick atmosphere is, as some already stated, because it's so bloody cold. You can do the simple atmospheric calculations and show that at the tempertures of Titan, it can hold that atmosphere pretty nicely.

        A good place to look for details is _The New Solar System_, Beatty, Petersen, and Chaikin, editors.
    • Think cold atmosphere (i.e., denser & with less energy -> less able to escape), with the additional assistance of Titan being small.

      Why does small matter? Because g falls off as distance squared. On a small moon of given mass, the force of gravity at the surface will be greater than on a moon of the same mass but larger radius (i.e, less dense).
    • For an interesting, related read, see Carl Sagan's book, "Pale Blue Dot". Wonderful pictures, insightful background on the plan. The book was published a few years before the launch. Sagan makes the trip to Titan, the potential discoveries, tantalizing. And here we are, so many years later, with the Cassini finally reaching its mark. Dr Sagan would have been on the edge of his seat just waiting to learn what we are about to learn.
    • The real question is if Titan has a stargate.
    • How does Titan keep its thick atmosphere?

      Because Titan sucks.

      Mimas RULES BAY-BEE!!

      That's no moon! It's a space station. Oh wait. It's a moon. Nevermind.

  • by pwroberts ( 600985 ) <slashdot@p[ ] ['wro' in gap]> on Saturday April 03, 2004 @09:53AM (#8755316) Homepage Journal
    They'll discover icebergs up there next...

  • by JessLeah ( 625838 ) on Saturday April 03, 2004 @10:14AM (#8755386)
    ...i.e. *kof kof* EUROPA... why Titan?

    Hydrocarbon seas. Could there be interest here by the oil industry? Makes you wonder... ;)
  • Oily sludge (Score:5, Funny)

    by Anonymous Coward on Saturday April 03, 2004 @10:20AM (#8755406)
    The model assumes Titan is pockmarked with seas made of 70 per cent ethane, 25 per cent methane, and 5 per cent nitrogen, and partially coated with an oily sludge.
    That's no moon, that's a teenager!
    • No sir! We are the US Dept of Defense are declaring war on the Titans for they might harbor WMD! See with a quarter of their seas being natural gas, we cannot allow their tyranny to continue!
  • Life imitates art? (Score:5, Interesting)

    by bpbond ( 246836 ) on Saturday April 03, 2004 @10:31AM (#8755434) Homepage
    Code Of The LifeMaker [], by James Hogan, is a SF novel about the first explorations of Titan--nitrogen atmosphere, methane seas, water-ice continents covered by nitrogenous-hydrocarbon soils. And, of course, its indigenous population of sentient, medieval robots, that destroy the first Terran probes and subsequently meet humans.

    Hogan's a clunky, dated writer, but it's an entertaining read. And if Huygens mysteriously fails on the surface next year...
    • by Anonymous Coward
      Fuck that, read Baxter's 'Titan' if you really want a hard sf view of the place. Depressing, too.
  • by Altima(BoB) ( 602987 ) on Saturday April 03, 2004 @10:34AM (#8755443)
    I hope I'm not the only one, but looking at those pictures made me remember how beautiful Saturn is... it has a sense of unreality about it, it just looks so perfect. The atmosphere's bands all seem to be perfect rings around its surface, one part of me asks "why," the other part thinks "who cares, it looks pretty."

    I know this could prolly be considered off topic, but I was just struck by the pictures of the planet and I wonder how, when so many dazzling images of space exist, can anyone act so ambivalent about space programs? It just doesn't make sense to me.

    Oh and was I the only one who pictures a bizzare version of The Perfect Storm when reading about those waves, a more boring movie with less waves and it takes longer to climb each one. I think Hollywood should begin pre-production in May.
    • Oh and was I the only one who pictures a bizzare version of The Perfect Storm when reading about those waves, a more boring movie with less waves and it takes longer to climb each one. I think Hollywood should begin pre-production in May.

      I think you're on to something! Imagine, we could send Bruce Willis, George Clooney, and Mark Walhberg into space to harvest ethane in titan's oceans. They all get caught in the 70-80ft waves and die. I think it would sell pretty well.
    • I hope I'm not the only one, but looking at those pictures made me remember how beautiful Saturn is

      I agree! Actually, I have always found Saturn to be absolutely beautiful -- I have a tattoo of it on my right arm.

      On an unrelated topic, I know the guy who did the X-ray shadow observations. If you asked me who among the people I know is least likely to wind up on the front page of /., I would have guessed Koji.

  • by Anonymous Coward
  • Cassini probe's Blog (Score:4, Interesting)

    by jayrtfm ( 148260 ) <jslash@sophont . c om> on Saturday April 03, 2004 @12:49PM (#8756151) Homepage Journal
    The Cassini probe has his own blog [].
    Anthropomorphized space probe's blogs started in January, and got more popular last month when some JPL'ers started ones for the GOES and FUSE satellites.
    Here [] is a list of 14 active space probe's blogs.
  • (I know they aren't really storms, but "prolonged atmosphereic distrubances" doesn't fit in the title box.)

    Why are Saturn's dark spot, Jupiter's Great Red Spot, El Nino, etc., all in the southern hemishperes of their respective planets? It really dosn't make sense.
    • Saturn's southern hemisphere is currently receiving more sunlight (i.e. summer), so one might expect solar heating to cause turbulent convection in the southern hemisphere. Half a Saturn-year from now (15 Earth years), there may very well be storms in the northern hemisphere. El Nino is a bit of a red herring. There's only been one recorded hurricane in the southern Atlantic (this week), and hundreds in the northern Atlantic. The distribution of land masses is asymmetric, so we should expect this.


  • I bet Halliburton and half a dozen other petroleum companies are already busy making plans to bring those Hidrocarbons (petroleum, Natural Gas) back to earth maybe by oleoduct ;-)
  • by techno-vampire ( 666512 ) on Saturday April 03, 2004 @04:11PM (#8757364) Homepage
    Back in the 80's, JPL changed the course of Voyager I to go behind Titan. The distance at which the signal started to drop, and the rate it dropped at gave us very good measurements of the atmosphere's depth and density. In fact, if the probe's distance from the center of Titan had been cut in half, it would have crashed. That's right, it was less than two radii out! I know, because I worked with the man who wrote the navagation system they used back then (The late Daniel J. Alderson.) and stll know, slightly, the man who used it for this, Bob Ceserone.
  • Ssh! better not tell the Americans! THey might decide to go there to look for Weapons of Mass Distraction
  • In a related story, NASA was busy trying to figure an efficient method for charging the newly dicovered inhabitants of Titan for the x-rays we now have of them.

    A spokesperson from the Chandra X-Ray Telescope team said "The folks on Titan are remarkable similiar in general construction, to human beings, except the have 5 arms, are 10 feet tall, and seem to sit around drinking a hydrocarbon beverage." The spokeperson went on to say that we here on Earth, may well have the interplanetary X-Ray market sewn u
  • Click [cel]! It's a Celestia link to a similar distance as Cassini when that picture was taken (and with a zoom of about 60x). You should see Saturn and it's moons as Cassini did. Maybe. :)
    • Sorry, /. broke the link. Copy/paste below into address bar .

      cel://Freeflight/2004-04-02T05:37:38.73188?x=AIC Qu xq4XS2ZDA&y=CryD4cS499z//////////w&z=VcrQjrvK3BZ5/ ////////w&ow=0.917275&ox=0.137113&oy=0.355513&oz=- 0.115832&select=Sol:Saturn:Dione&fov=0.455644&ts=1 .000000&ltd=0&rf=40923&lm=0
    • I couldn't get your link to work, even with revisions, but the view from around Saturn's satellites is just gorgeous.

      Perhaps it's not the sole job of future probes to get us better textures for Celestia, but it'll be a nice side-effect :)

      For those without Celestia - do yourself a favor and download it! [] It's one of the best-feeling 'space exploration' simulators I've encountered, and you can't beat the price ;)

      Now, all we need is this as the base engine for Elite III: More Stars Than You Can Shake A Pr

  • Apparently a variety of infrared images of Titan at different wavelengths [] have been taken from the European Southern Observatory. These different wavelengths allow features at different depths in the atmosphere to be visualized, revealing dynamic and asymmetric atmospheric features, one dubbed the Southern Smile.

The system will be down for 10 days for preventive maintenance.