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Space Science

Cassini-Huygens Reaches Phoebe 178

Posted by michael
from the bulls-eye dept.
Anonymous Explorer writes "The Cassini-Huygens probe is set to fly by the largest outer Saturn moon of Phoebe today. Cassini will be roughly 2000 km from the surface of Phoebe at 1:56 Pacific time Friday, June 11. Thats pretty darn close. The newest images of Phoebe are already thousands of times better than the previous ones taken by the Voyager 2 mission in 1981. Phoebe is interesting in that it maintains a retrograde orbit around Saturn. This has lead to the hypothesis that it is an ancient asteroid that has been captured by the gravitational pull from Saturn. Phoebe may provide some important insights into the composition of early building blocks of our planets. Phoebe was discovered in 1898 by American astronomer William Pickering. As always, discussion about this mission can be found at #cassini on irc.freenode.net."
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Cassini-Huygens Reaches Phoebe

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  • Google search, "define: retrograde [google.com]"
  • Parking (Score:5, Funny)

    by tedgyz (515156) * on Friday June 11, 2004 @01:27PM (#9399677) Homepage
    Hmmm, that deep crater looks like a good place to park the Millenium Falcon while we wait for that Star Destroyer to leave.
  • Wow (Score:5, Interesting)

    by Mick Ohrberg (744441) <mick.ohrberg@gma ... com minus author> on Friday June 11, 2004 @01:28PM (#9399690) Homepage Journal
    This is just amazing. We're really reaching further and further out in the solar system. And not just by blindly sending probes out there, but by consciously seeking to get close to other bodies in the solar system, and really finding out. I really hope I get to see the Europa landings in my lifetime.
    • by proj_2501 (78149) <mkb@ele.uri.edu> on Friday June 11, 2004 @01:30PM (#9399737) Journal
      don't you humans get the message? what part of "ATTEMPT NO LANDINGS THERE" is hard to understand?
    • by Rei (128717) on Friday June 11, 2004 @01:50PM (#9400012) Homepage
      I'm really excited about the new photos... I hope they release full res mosaics and don't delay... pre-processed surface texture and heightmap data would be nice, too.

      If you want to get an idea of just how high res pictures they're going to get, do the following:

      1) Download the program "Celestia". Build and run it.
      2) While it is building, pull up the last picture that Cassini took of Phoebe.
      3) When Celestia comes up, full screen it.
      4) Go into the configuration and tell it to include full details. Exit the configuration menu.
      5) Press enter, and type in "Phoebe". Press enter.
      6) Press 'g' to go to Phoebe (note: Phoebe is currently false-texture in Celestia, since we don't know much about it)
      7) Middle click and hold down, and drag the mouse until you're at a distance of 658,000 kilometers.
      8) Press ctrl-'+' to zoom, until the resolution of Phoebe that you're seing on the screen is about the same as that in the NASA picture (note: resolution, not size. The nasa picture is enlarged).
      9) Without changing the zoom, hold middle click againa nd drag the mouse until the distance is 2,000 kilometers.
      10) Hold down shift, and use the arrow keys to look around. That's the sort of resolution images that they should be able to get.

      Impressive, isn't it? I can't wait! :)
    • you ain't seen nuthin' yet... in a few days time, (July 1st) the probe flies through a gap in the rings [nasa.gov]...

      Cassini will approach Saturn from below the ring plane. The spacecraft will cross through the large gap between the F Ring and G Ring. At this time Cassini will be 158,500 kilometers (about 98,500 miles) from Saturn's center. This crossing will occur one hour and 52 minutes prior to the spacecraft's closest approach to Saturn.

  • More about Phoebe (Score:5, Informative)

    by JaF893 (745419) on Friday June 11, 2004 @01:30PM (#9399734) Journal
    Here are some links about phoebe and the Cassini-Huygens:
    Phoebe [wikipedia.org]
    Cassini-Huygens [wikipedia.org]
  • That moon looks like one of my recent attempts at Photoshop :S

    mmm gradient shading :)
  • by david.given (6740) <dg AT cowlark DOT com> on Friday June 11, 2004 @01:35PM (#9399811) Homepage Journal
    Look, guys, saying that it arrives at '1:56 PST' is bloody useless. Apart from the fact that Pacific Time is largely meaningless to most of the world, you don't even say whether that's morning or afternoon!

    Having scoured the web sites --- it's actually quite hard to find the information --- the probe is doing the close flyby at 2056 UTC (i.e. about two and a half hours from now). Assuming I've got the daylight saving compensation right, of course...

    • Then you've never found timeanddate.com [timeanddate.com]
      • Then you've never found timeanddate.com

        No, I hadn't... but it still doesn't help. The website won't let me pick a timezone, it wants me to pick a city --- and I don't know where the hell PST is!

        I did make a wild stab and fed in Los Angeles, being the only west-coast city I know in the US, and it came out the same, so I am reassured.

        Seriously, guys, if you're talking to a world audience it's so much more convenient if you use UTC. Everyone knows how to convert UTC to and from their local time; it's con

        • I knew how to convert PST to EST. I wouldn't be sure how to convert UTC to EST.
        • Seriously, guys, if you're talking to a world audience it's so much more convenient if you use UTC. Everyone knows how to convert UTC to and from their local time; it's considerably harder to convert to and from some bizarre local time half way round the planet.

          I'd be willing to bet that there are far more Slashdot readers who know how to convert from PST than know how to convert from UTC. Hell, I bet a good portion of people who read that didn't even know what you were talking about when you said UTC.

          B
          • UTC comes up when setting time zones of most (if not all) linux distributions. So most have heard of it
            Of course, if you're like me, you ignored it and had your computer watch running 9 hours ahead of your system clock...
            But yeah, PST = Pacific Standard Time. So try looking for a city on the pacific (YellowKnive, Vancouer, Seattle, Portland, LA, San Fran, and Tijunana are all common choices i think). Also, the one refers to 01 as there is no pm or am used you can assume its 24 hour time
          • -> Log into your Linux box.
            -> Type: date -u
            This shows the current UTC time.
            -> Now that you know what the UTC time is, figure out how many hours off you are and baddabingbaddaboom, you know how to covert UTC to localtime. I suppose I could post a shell script but I am too lazy.
    • by gatkinso (15975) on Friday June 11, 2004 @01:40PM (#9399873)
      you get to use local time! :P
    • And your damnable metric time!
    • by Billy the Mountain (225541) on Friday June 11, 2004 @01:47PM (#9399974) Journal
      the probe is doing the close flyby at 2056 UTC (i.e. about two and a half hours from now

      Sorry to confuse the issue even more, but since the probe is 80 light minutes from the earth, does that mean that 2056 UTC is when it's actually happening, or is that when we finally find out that it happened 80 minutes in the past?

      BTM
    • it's at 13:56 PDT ERT ... where ERT means Earth Receive Time.

      It's at 20:56 UTC ERT, the SCET (Spacecraft Event Time) was at 19:34 UTC.

      See this link for an explination of the time conventions: http://www2.jpl.nasa.gov/basics/bsf2-3.html [nasa.gov]

      Actually UTC is damn awful time system because of leap seconds which cannot be predicted. All calculations must use ET (Ephemeris Time) which is almost always SCET. The 'REAL' flyby occured around 19:35 ET, the exact time to be determined from tracking after the flyby.
      • UTC is damn awful time system because of leap seconds which cannot be predicted. All calculations must use ET....

        For the purpose at hand (communicating to humans who live around the world about time to within a minute or two) UTC is just the thing.

        Leap seconds are necessary for many purposes because the earth spins at an unpredictable rate, and people (and navigators) like to keep in sync with sunrise, star transits, etc.

        You might want to check your own reference about "ET":
        It is common to see outdat
        • ET, TT, TAI, DT, etc... all just have a fixed offest from each other so it doesn't matter which one you use. ET is that standard (despite what my reference said).

          Navigators (for spacecraft) don't use UTC, precisely because they want to keep in sync with the actual motion of the planets.

          Missions like Cassini ar planned several years in advance (Cassini is planned until 2008). Unfortunately, Cassini is planned in UTC (to sync with the wall clock). If a leap second randomly appears, all of those plans w
          • We agree that for spacecraft navigation, UTC is inappropriate. But UTC and timezone offsets from it are the right thing for everyday use on earth by people that want "noon" to have a long term correlation with the position of the sun. So all I'm saying is that we need both UTC for the latter, and something else for things like spacecraft navigation.

            Further, those "fixed offsets" do matter in the real world, so it makes sense to promote a single standard designed for avoiding leap seconds. It is really u
  • Everything is a moon (Score:2, Interesting)

    by D3 (31029)
    Saturn has billions of "moons" if something that small (137 miles?!?) is considered one. The composition of the rings alone makes up a ton. So why is this one more interesting than others?
  • Anyone have info on when the pics will make the transit and be broadcast? The Cassini site at JPL seems to be acting weird ATM. Looks like NASA can send a probe to Saturn but can't build a website to resist the /. effect.
    • Call it a hunch, but I'd think that JPL and NASA arent using their web server(s) to download images from the probe.
      • I realize that.

        I meant that I can't reach the website to find out when the pictures will be posted somewhere. Does anyone have that information?

        Inability to post in understandable language is the Friday effect :)

    • Pictures start coming down to the ground tomorrow morning and are dowloaded all day. Right now Cassini is busy taking pictures so it can't point it's antenna at Earth. And the pictures will take all day to download because even though they are using an antenna as tall as a 25 story building, so still can't get a very high data rate transmitting at 80 W from 10AU.

      After that they will take some time to process, but when they are released they will either be at www.ciclops.org or saturn.jpl.nasa.gov.
  • When are we gonna privatize space so commericial entities can quickly outpace NASA?
    • It's happening right now. Exciting times ahead. Better pay attention to it, 'cus this is something you'll be telling to your (grand)children.

      See X-prize.
    • by EXTomar (78739) on Friday June 11, 2004 @02:33PM (#9400561)
      Its lovely how there are cries of privatizing space and how we'd get to the stars faster if we only let regular joe mega corporations build spaceships. There plans go something like the familar pattern we've seen all over the place in /.

      1. Privatize Space Exploration
      2. ????
      3. Profit!!

      Right now there is little to no incentive for a company like Lockhead-Martin to build system to land people on the moon and build a moonbase. Science is a terrible profit motive unless you can find practicle applications. And since we know the moon isn't made of cheese (which you can sell) or littered with diamons the size of footballs no company has this burning desire to go into space. Its too costly to make money at it.

      So we are stuck with government ventures. I'm glad the US, Russia, and China push these things but I have no illusions about how this works. They are doing it because their is a small bet of prestigue and a good way to spend military for R&D without making it so obvious.

      So until you find out that Pheobe is made of 99% gold or Mars has rubies the size of boulders or something else interesting there is little point ot privatizing space over having world governments fund it. Simply put, governments don't care about profits.
    • Space is space, it's not a government industry. No one owns it. Until someone makes landlclaims, that is. This would of course be seen as a hostile act by everyone else. Do whatever you want with it, but please do it a few parsecs away.
      I for one can't wait until we can go out there, where there are no semi-corrupt governments to deal with (yet). I'd just love to take off and explore the galaxy on a ship like the Heart of Gold or something... :) Seriously. It would be so much more fun than going to work.
  • Anticipation (Score:5, Informative)

    by amightywind (691887) on Friday June 11, 2004 @01:51PM (#9400024) Journal

    The newest images of Phoebe are already thousands of times better than the previous ones taken by the Voyager 2 mission in 1981.

    No, but it is hoped they will be. At best, the newest released images are 10x better than Voyager. Expect the high res images later today. You are getting ahead of yourself.

  • Captured asteroid? (Score:5, Informative)

    by barakn (641218) on Friday June 11, 2004 @02:03PM (#9400160)
    This has lead to the hypothesis that it is an ancient asteroid that has been captured by the gravitational pull from Saturn

    Phoebe is actually believed to be a captured Kuiper Belt object (KBO). This means its composition might be very icy/organic, making it more like a non-active comet than an asteroid.

  • Phoebe is interesting in that it maintains a retrograde orbit around Saturn. ... Phoebe may provide some important insights into the composition of early building blocks of our planets. Phoebe was discovered in 1898 by American astronomer William Pickering.

    Weren't you in class the day they told you not to start every sentence with the same word? :-)

    At least you didn't start each sentence with "I"...

    Cassini-Huygens Reaches Phoebe Posted by michael on Friday June 11, @01:20PM from the bulls-eye dept. Ano

  • by Jboy_24 (88864) on Friday June 11, 2004 @04:42PM (#9401923) Homepage
    One of the greatest things about the Mars rovers page, is that you don't have to wait until NASA releases "press release" images in order to see the latest. You can access them through the mars rovers RAW images site probably a few hours after NASA got them.

    I havn't seen any links to such a database for Casinni, but I really hope they set one up soon!

It is the quality rather than the quantity that matters. - Lucius Annaeus Seneca (4 B.C. - A.D. 65)

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