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Cassini Confirms New Moon of Saturn

Posted by samzenpus on Wed May 11, 2005 11:10 PM
from the made-of-cheese dept.
Space Technology
pipcorona writes ""In a spectacular kick-off to its first season of prime ring viewing, which began last month, the Cassini spacecraft has confirmed earlier suspicions of an unseen moon hidden in a gap in Saturn's outer A ring. A new image and movie show the new moon and the waves it raises in the surrounding ring material."
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[+] Cassini's Primary Mission Ends, Two-Year Extension Begins 46 comments
wooferhound points out recent news that the Cassini probe has completed its original four-year mission and is beginning a two-year extended mission, which was authorized earlier this year. Cassini's first mission brought us a treasure trove of information about Saturn and its various moons. The new mission will target two of those moons in particular for further study: Titan and Enceladus. Quoting: "The spacecraft is extremely healthy and carries 12 instruments powered by three radioisotope thermoelectric generators. Data from Cassini's nominal and extended missions could lay the groundwork for possible future missions to Saturn, Titan or Enceladus. [The two moons] are primary targets in the two-year extended mission, dubbed the Cassini Equinox Mission. This time period also will allow for monitoring seasonal effects on Titan and Saturn, exploring new places within Saturn's magnetosphere, and observing the unique ring geometry of the Saturn equinox in August of 2009 when sunlight will pass directly through the plane of the rings."
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  • "Name That Moon" Contest (Score:5, Funny)

    by TripMaster Monkey (862126) * on Wednesday May 11 2005, @11:11PM (#12506338)


    From TFA:



    The new body has been provisionally named S/2005 S1.


    Well, that just rolls off the tongue, doesn't it?

    Looks like it's up to us...please post your suggestions for the new moon's name below.

  • What's so special about a new moon? (Score:5, Interesting)

    by psetzer (714543) on Wednesday May 11 2005, @11:17PM (#12506376)
    I mean, really? Every time they find a new one, the things just keep getting smaller. What's next, a piece of ejecta from another moon the size and shape of a '74 Chevy Impala? Might as well start naming the debris in the rings.
    • The impala is not recognised as a unit of measure. Please use Volkswagons, or ISO Standard Bathtubs.

      I'm not sure where the exact cutoff is. I'd assume anything in the decivolkswagon range would simply be considered as flotsam unworthy of a name, unless somebody wants to try to catalogue everything in the rings! You'd need a lot of mountain dew.
    • I'm repeating myself here (see my post below)...

      This satellite is actually interesting since it may hold a key on how to retain a gap in the A-ring. It has to do with this small body of a satellite perturbing the neighboring, smaller dusts and removing them from the region effectively.

      Somelike that can be studied numerically (n-body problems) to prove the ring's composition, etc. A nice test case for n-body problem.

      [I really should be moderating today but...oh well.]

  • So everythings a moon now? (Score:5, Funny)

    by mnmn (145599) on Wednesday May 11 2005, @11:19PM (#12506384) Homepage
    7km across? Compared to Saturn thats tiny. Thats like saying the ISS is a moon.

    So how do you draw a distinction between a moon, a natural satellite, asteroids and space junk? You can either say the moon Earth has an asteroid orbiting it... or that Earth has many moons orbiting it, only one of which is large enough to see.

    So if I pay the Russian space program to launch my 1kg rock in lower orbit, do I get to name my moon, or will they just name it
    S/2005 SR26GC3.14159265357?

    Which makes me wonder, have we named or numbered our own moon yet? Can I call shotgun and call it 'fp!'?

    • Re:So everythings a moon now? (Score:5, Informative)

      by Daedalus-Ubergeek (600951) on Wednesday May 11 2005, @11:22PM (#12506416)
      I do believe our own moon is named Luna, which would be where you get the word "Lunar", although you rarely ever hear anybody call the moon by its actual name.
      • Well, at least in Spanish-speaking countries we always call it Luna.
      • Luna is the goddess of the moon according to the Romans (see http://dictionary.reference.com/search?q=luna [reference.com] for reference). So that gives you Lune in French and Luna in Spanish/Italian.

      • "actual name"?

        Hmm, I thought the actual name was "the Moon", and Luna a term rarely used to distinguish it from other moons whenever necessary. Why would people rarely use an actual name?

        That it's the actual name is as debatable as Sol is the actual name for the Sun, something I also can't really say, even if we have "solar".

        I guess both these names can be said to be occasionaly used to personify these celestial bodies though.

      • Re:So everythings a moon now? (Score:5, Informative)

        by metroplex (883298) on Thursday May 12 2005, @02:12AM (#12507071) Homepage
        Actually, in all Romance Languages (those derived by latin), the Earth's moon is called something like "Luna".
        • Italian: Luna
        • French: Lune
        • Spanish: Luna
        • Portuguese: Lua
        • Romanian: Luna
      • I do believe our own moon is named Luna, which would be where you get the word "Lunar", although you rarely ever hear anybody call the moon by its actual name.

        What's next? Calling the sun something stupid like "Sol"?
        • What's next? Calling the sun something stupid like "Sol"?

          Just in case you're not being sarcastic, as our Solar System's planets are actually named after Roman gods, the name for our Sun would be Sol just as Earth is actually called Terra.

          For a list of names, see this compilation [nineplanets.org].
      • I do believe our own moon is named Luna...

        Actually, our moon doesn't technically seem to be named anything. The International Astronomical Union (IAU), which many people consider to be the authority on such matters, doesn't seem to have any documents that specify what our moon's name is. Some of their documents use the name Moon with a capital M (eg. "Report of the IAU/IAG Working Group on Cartographic Cordinates and Rotational Elements of the Planets and Satellites: 2000" http://astrogeology.usgs.g [usgs.gov]

    • Re:So everythings a moon now? (Score:5, Interesting)

      by helioquake (841463) * on Wednesday May 11 2005, @11:30PM (#12506460) Journal
      I'd usually agree with your sentiment. But this finding is rather important and scientifically useful (for some, not really for me).

      The significant thing is this: this moon, how small it is, may regulate the way a gap in the A-ring evolves (or stay clear of smaller rocks),

      The effect of the moon's gravity is small, but not small enough to be ignored by the material nearby. Some smart guys can run some numerical analysis to study what the rings are made of, and how a single massive (relatively) body can perturb its surrounding smaller particles.
    • To distinguish when a moon is a moon and not, say, a large orbiting asteroid is easy. It occurs at the same time when bread becomes toast.

      Ask that question (Bread -> toast) to some people who's IQ lies on the wrong side of the bell curve - you'll be amazed at the looks you'll get.

    • Re:So everythings a moon now? (Score:5, Funny)

      by Greyfox (87712) on Wednesday May 11 2005, @11:47PM (#12506529) Homepage Journal
      Thats like saying the ISS is a moon.

      That's not a moon. It's a space station.

  • Roche limit? (Score:5, Interesting)

    by Gangis (310282) on Wednesday May 11 2005, @11:24PM (#12506424) Journal
    I'm no astronomer, but I remember hearing in Astronomy class about the Roche Limit, the absolute minimum distance that an orbiting body can be from a planet before it'd be disintegrated by the gravity. I also remember hearing that Saturn's rings could have been developed as a result of objects falling within the Roche Limit and disintegrating, thus adding to the ring. This object seems much larger than most of the ones in the ring structure, though. I find that really odd. But then again, IANAA. :P

    • Re:Roche limit? (Score:3, Informative)

      by Anonymous Coward
      The Rings are inside the Roche limit, which is the point where tidal forces will destroy a satellite. However, the Roche limit assumes a liquid body. A small solid body has enough physical strength to hold itself together even inside the Roche limit.

    • Re:Roche limit? (Score:5, Informative)

      by imsabbel (611519) on Thursday May 12 2005, @02:58AM (#12507217)
      The Roche limit only works for large bodies, when you assume that the moon is only held together by its own gravity.

      For very small, rocky moons, the tensile strenght of the rock itselv enabls them to exist nearer than the roche limit. Its nothing extremely longtime-stable, but otoh, the tidal forces on a small moon arent very large.

      Also, the roche limit is only a contant (2.xxx*R_bigplanet or so) if the bodies have the same density. If the objects is, for example, a captured iron asteroid, its roche limit can be VERY close to a not very dense saturn.
  • Cool images and data:
    Map and Images of Titan [arizona.edu] from Hubble Space Telescope
    Nasa Titan Photojournal [nasa.gov]
    Saturnian Satellite Fact Sheet [nasa.gov]
    Phoebe [space.com] best image so far, from Voyager2 in 1981!

  • Good use of science money (Score:3, Insightful)

    by qurk (87195) on Wednesday May 11 2005, @11:43PM (#12506518)
    At least this money is going to find new and useful things. Unlike my state (Kansas) which seems to think that the board of education needs to make us all a laughingstock and put their damn religion in our schools in every science textbook. Why not just require a class, like "Majority religion/philosophy-science indocrination". Look, I learned a LOT from reading Isaac Asimov essays, is there a reason I had to go the the library and check out books of essays from a science fiction author to learn about science? Ya! My state board of education is really badass, getting the job done, and is really cool!

  • Interesting that... (Score:4, Interesting)

    by vikstar (615372) on Wednesday May 11 2005, @11:45PM (#12506524) Journal
    the waves caused are asymetric, as if the moon is moving faster than the immediately surrounding debris. But thats impossible, because it would move the moon to a higher orbit, or the debris to a lower one, right? Can anyone explain this seemingly wierd phenomenon? Also notice the waves caused on the inner darker ring, what is the cause of that?

      • Re:Why asymetric? (Score:4, Informative)

        by CheshireCatCO (185193) on Thursday May 12 2005, @09:47AM (#12509131) Homepage
        You nailed it. The ring material inside the S/2005 S1's position is moving faster than the moon, so the waves that the moon excites appear ahead of the moon's present position. (That material just had a close encounter.) The other edge of the gap is orbiting more slowly, so the moon PASSES it, so the waves appear behind the moon.

        I'd avoid the word "turning" because it suggests a solid object. The rings are anything but solid.

        There are other ways to make asymmetries in these wakes. If the moon isn't well-centered in the gap (although it isn't clear why it wouldn't be) or has a significant orbital eccentricity, you'll get asymmetry as well.

  • That's not a moon! That's a... (Score:3, Insightful)

    by Jugalator (259273) on Thursday May 12 2005, @01:43AM (#12506964) Journal
    ... unsually large particle in Saturn's ring system??
    • Oh please god no!
      What are you on? That would make /. look like a gay christmas tree. All of your suggestions are horrible.
      1. If you need images, post a link. If you don't have your own webserver or atleast host space to put images on, please hand back your /. UID.
      2. Emoticons are plaque of messageboards. I want to strangle someone each time I use MSN after fresh install and haven't turned them off. What ever happened to the good old smileys?
      3. Ok, you just have to be trolling...

    • Re:In space no one can see your color? (Score:5, Interesting)

      by Mikey-San (582838) on Thursday May 12 2005, @02:41AM (#12507161) Homepage Journal
      Imagine being in England for a moment. It's 3 a.m., and you're sitting on one side of the Thames River.

      Your friend Bob is perched in his chair on the other side.

      Your camera's all set up and ready to snap a picture. Just when you're about to snap, you realize that the nearest streetlight is three miles to Bob's left. Seeing that the Thames isn't a sneeze's distance across, you know that the dinky flash on your camera is pretty useless.

      You whip out your trusty imaging spectrometer camera lens and line up the shot with Bob again. Bob's giving off some good x-ray emissions, and those come across just fine.

      You could've used a really, really awesome lens and captured a bad photo of Bob--he still reflects some light, though it's a ridiculously small amount--but the IR lens gave you a more descriptive picture of Bob. Why? Mr Bob the Planet Man doesn't give off his own visible light, but he certainly emits x-rays on his own.

      This scales higher:

      In this new-but-similar scenario, you're flying over England. You're trying to take a picture of Bob and his lazy ass, but all you can see, no matter how much light you shine down onto the city below, are the lights from the buildings, bridges, and streetlamps. There's just too much noise to find ol' Bob in that galaxy of lumens.

      You've got all these lights shining on Bob, but unlike the first scenario, there's /too much/ light to see Bob; all you see are stars, so to speak, drowning out the nearby planets. Well, in x-ray mode, your camera can see that while those stars are emitting x-rays, so is Bob, just like before. You're not seeing a faint image of Bob drowned out by the only light illuminating him, you see Bob's x-ray signature approximately ten feet to the right of that cluster of streetligts.

      The universe is a dark place, but sometimes it can be TOO bright! It's a good thing I remembered a towel!

    • Re:In space no one can see your color? (Score:4, Informative)

      by bcwright (871193) on Thursday May 12 2005, @02:45AM (#12507179)
      Resolution. Most space cameras work by detecting light falling on a CCD (Charge-Coupled Device); if the camera was full color, then the resolution would be cut by at least 2/3 because you'd have to devote 1/3 of the CCD to each of the primary colors. (It might be even worse than that if your imaging system wasn't 100% efficient at directing the color components to the proper pels on the CCD). You can obtain the effect of a color camera by using different lens filters and taking multiple pictures and then composing them into a single image - this is what's usually done when a color photograph is desired. By doing that you can produce an image that's exactly what you could obtain with a color camera, but at a higher resolution and without having to use a higher resolution CCD. Also, that way your pictures aren't limited to using a selection of color components that are compatible with those the human eye sees - you can use the filters to "see" parts of the spectrum outside the range that's visible to the human eye.
    • People have already more or less addressed this, but I'll speak up anyway.

      They DO send color cameras into space. After a fashion. You have surely seen the color images taken by Cassini's ISS instrument already, so you know that it is possible. To do this, they put various filters in place and expose the CCD to take the image. The colors are then combined (with extreme love and care to get accurate color, in many cases) to make a color image. However, this clearly takes at least three times the exposur

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