Slashdot Mirror


Cassini Probe Does Titan Flyby

EccentricAnomaly writes "Today, Cassini had its first close encounter with Titan around 8:30AM PDT. Data from the flyby will start coming down around 6:30PM PDT, and you can watch the pictures live on NASA TV. If you want higher resolution or just to stare at one picture for a while, the raw images will be put on the web right away, with pretty press images to follow the next day. And if you want to know about the observations planned for the flyby, you can read this PDF or watch this animation."

35 of 115 comments (clear)

  1. 4Gbit Solid State Recorders by fembots · · Score: 5, Interesting

    From NASA's faq - "Cassini stores the gathered information on two Solid State Recorders (SSR) with a combined capacity of 4 gigabits, about the volume of a compact disk (500MB)."

    It seems scientists are pretty confident that they can unload much data during Cassini's 9 hours downlink session.

    Imagine if there were some downtimes when earth communication cannot be established for a couple of days...

    1. Re:4Gbit Solid State Recorders by Macphisto · · Score: 5, Funny
      Imagine if there were some downtimes when earth communication cannot be established for a couple of days...

      Good Lord, man! What in blazes are you planning?

    2. Re:4Gbit Solid State Recorders by badfrog · · Score: 5, Informative

      Interference has always been a huge factor, the Space Shuttle still used iron-core memory in its systems in the late 80s, because it wasn't affected by radiation. Can't just pop in some SDRAM and expect it to work out there.

    3. Re:4Gbit Solid State Recorders by HunahpuMonkey · · Score: 5, Informative

      > From NASA's faq - "Cassini stores the gathered information on two Solid State Recorders (SSR)
      > with a combined capacity of 4 gigabits, about the volume of a compact disk (500MB)."
      >
      > It seems scientists are pretty confident that they can unload much data during Cassini's 9 hours
      > downlink session.
      >
      > Imagine if there were some downtimes when earth communication cannot be established
      > for a couple of days...

      According to CNN that very problem exists. The buffers in those recorders are in danger of writing over the data before it can sucessfully be sent to Earth.

      "The flyby of Titan was expected to go smoothly in space, but bad weather on Earth could affect Cassini's transmissions to the Deep Space Network, scientists said.

      Cassini has only one chance to send data back to Earth before it is overwritten with data from its next set of observations, scientists said."

    4. Re:4Gbit Solid State Recorders by jnik · · Score: 2, Insightful
      It seems scientists are pretty confident that they can unload much data during Cassini's 9 hours downlink session.

      Imagine if there were some downtimes when earth communication cannot be established for a couple of days...

      What would more storage buy you? It wouldn't increase the downlink bandwidth, and there's only so much time available to transfer it down, so you'd just get further and further behind. Losing downlink time means losing data, period.

      Telemetry bandwidth is always an issue; instruments always produce data at a rate greater than can be sent to the ground.

    5. Re:4Gbit Solid State Recorders by Rei · · Score: 4, Insightful

      Not *always*. When Cassini isn't doing an encounter, it's sitting around doing pretty much nothing (regular bits of telemetry data, random readings, occasional snaps of Saturn or distant shots of moons, etc). Greater storage space, even if not accompanied by an increased bandwidth improvement, allow you to gather more data from your insturments during flybys, which you can transmit during the less-important inter-flyby periods.

      --
      POTUS Witch Hunt tracker: 75 charges filed against 19 witches, 4 witches cooperating and 5 witches have pled guilty.
    6. Re:4Gbit Solid State Recorders by deglr6328 · · Score: 2, Interesting

      I can see how you might fit the images, spectra and other data in 500MB of storage but how do they fit the synthetic aperture radar data in there? It must be huge!.....anyone know?

      --
      - "Hear that?! The percolations are imminent! Cease your ingress!"
    7. Re:4Gbit Solid State Recorders by djvern · · Score: 2, Informative

      Actually, we have a saying: "The rain in Spain falls mainly on DSS-63" The rain is a very large concern for everyone here tonight. We have already requested a backup downlink session tomorrow in case of problems tonite. Basically, we stole a 70 meter antenna from another project. The critical data will make it down at the end of the Madrid pass, as there is dual coverage with a 34 meter Goldstone, CA station. Best of luck.

    8. Re:4Gbit Solid State Recorders by Tablizer · · Score: 5, Insightful

      Yeah, the next probes sent to space really should use microdrives for backup at least. I mean, put an IPod on a probe and not only will the probe be able to store tens of GBs of data, but it could even play MP3s on a simulated speaker through the entire mission. Besides, if a probe finds a representative of an intelligent race out there, it could use its IPod to swap music.

      This is why NASA does not hire 14-year-olds.

    9. Re:4Gbit Solid State Recorders by jnik · · Score: 3, Informative
      When Cassini isn't doing an encounter, it's sitting around doing pretty much nothing

      Hardly true. Now, granted, I don't have the Cassini instrument duty-cycle schedule right here, but I can at least take a quick look at the projected orbit plots. It looks like apicenter is about 60-70 Rs. Frontside magnetopause distance is 20-25 Rs (roughly), the flanks are likely further out, and I'd put money on the tail extending at least 70 Rs. Even on the front side I'm sure there's plenty of science to be done in the sheath, bow shock, and even upstream solar wind.

      So the plasma instruments and magnetometer would be busy for probably half the distance of each orbit. I imagine the cosmic dust analyzer is probably useful the whole time, and the UV cameras (I'm too lazy to compare the resolution to Hubble...). That's a lot of data.

      And it really does come down pretty slow. At 35 kbit/s, that's roughly a day and a half, best case, to empty the recorders, out of approximately two weeks for an orbit (not always being in "view", either, and the DSN sometimes needed for other things...).

      I'm sure somebody would find some use for extra storage if it were there, but the limitation doesn't mean Cassini's spending any great amount of time idle.

  2. Links to the actual Quicktime and GIF files by waynegoode · · Score: 5, Informative
    The links on the webpage open pop-up windows to show the video. You can't right click and save the files. I did a little right-clicking and source viewing and found the URLs of the actual files.
  3. 4 Gig recorders by Baumann · · Score: 3, Interesting

    They have to be confident. If the system goes for N days without contact, I suspect they'll have far greater worries than just overfull download buffers. Say like - why isn't our little lost machine talking to us?

  4. The raw pictures will be put up right away? by Dancin_Santa · · Score: 2, Interesting

    What if they spy aliens? Won't that cause a little alarm amongst the general population?

    1. Re:The raw pictures will be put up right away? by mikael · · Score: 4, Funny

      What if they spy aliens? Won't that cause a little alarm amongst the general population?

      No, the central government of Titan have contingency plans to reassure the Titanian public that anything they see is merely a weather balloon, a stray asteroid or a reflection of Venus.

      --
      Vintage computer adverts: http://www.vintageadbrowser.com/computers-and-software-ads
  5. The animation link web page, I meant to say by waynegoode · · Score: 2, Informative
    I am refering to the last link, the one about animations, http://ciclops.lpl.arizona.edu/view.php?id=500

    Sorry I left that out.

  6. Re:welll by pedroloco · · Score: 2, Informative

    If you're counting moons outwards from Saturn (or, more precisely, in order of increasing orbital semi-major axis length), Titan is more like the 19th moon (or 15th if 4 recently discovered moons are excluded).

  7. Aliens by Indy+Media+Watch · · Score: 4, Interesting

    I understand from the webpage that NASA TV can be received by anyone with a satellite decoder and presumably TV stations to rebroadcast images.

    They include "live mission feeds" and live images that we can see from the Cassini prove.

    Knowing NASA's lineage, is there any form of delay applied to these 'live' feeds? Or could we one day see something which may otherwise be classified (alien waving at the camera, dead astronaut) on the screen in real-time?

    --

    Indy Media Watch-Proctologist of the Internet

    1. Re:Aliens by Timesprout · · Score: 4, Funny

      Well normally when pixar do the special effects for these missions there are no issues. I believe the faking effects for this mission have been outsourced to Bollywood due to budget constraints so please dont be alarmed if the mission actually turns out to be a love story between Cassini and Hygens and several hirsuite men in colourful outfits burst into a song and dance routine halfway through it.

      --
      Do not try to read the dupe, thats impossible. Instead, only try to realize the truth
      What truth?
      There is no dupe
  8. ObStarWars by Anonymous Coward · · Score: 2, Funny

    That's no moon....

  9. CNN Story Link by Makoto916 · · Score: 2, Funny

    Here is a link to a CNN story that also has a nice video animation link of the event.

    Can't wait until Virgin Galactic offers rides out there! :)

  10. sci.space.news by noselasd · · Score: 4, Informative

    Subject: Cassini Image: Eyes on Xanadu
    From: baalke@earthlink.net (Ron)
    Newsgroups: sci.space.news
    Followup-To: sci.space.policy
    Date: 26 Oct 2004 09:25:07 -0700

    http://www.nasa.gov/mission_pages/cassini/multim ed ia/pia06107.html

    Eyes on Xanadu
    October 25, 2004

    Cassini image of Titan, revealing the bright continent-sized terrain
    known as Xanadu

    This image taken on Oct. 24, 2004, reveals Titan's bright
    "continent-sized" terrain known as Xanadu. It was acquired with the
    narrow angle camera on Cassini's imaging science subsystem through a
    spectral filter centered at 938 nanometers, a wavelength region at which
    Titan's surface can be most easily detected. The surface is seen at a
    higher contrast than in previously released imaging science subsystem
    images due to a lower phase angle (Sun-Titan-Cassini angle), which
    minimizes scattering by the haze.

    The image shows details about 10 times smaller than those seen from
    Earth. Surface materials with different brightness properties (or
    albedos) rather than topographic shading are highlighted. The image has
    been calibrated and slightly enhanced for contrast. It will be further
    processed to reduce atmospheric blurring and to optimize mapping of
    surface features. The origin and geography of Xanadu remain mysteries at
    this range. Bright features near the south pole (bottom) are clouds. On
    Oct. 26, Cassini will acquire images of features in the central-left
    portion of this image from a position about 100 times closer.

    The Cassini-Huygens mission is a cooperative project of NASA, the
    European Space Agency and the Italian Space Agency. The Jet Propulsion
    Laboratory, a division of the California Institute of Technology in
    Pasadena, manages the Cassini-Huygens mission for NASA's Science Mission
    Directorate, Washington, D.C. The Cassini orbiter and its two onboard
    cameras were designed, developed and assembled at JPL. The imaging team
    is based at the Space Science Institute, Boulder, Colo.

    For more information about the Cassini-Huygens mission, visit
    http://saturn.jpl.nasa.gov and the
    Cassini imaging team home page, http://ciclops.org

    Credit: NASA/JPL/Space Science Institute

    And

    Cassini-Huygens makes first close approach to Titan

    Today the NASA/ESA/ASI Cassini-Huygens spacecraft makes a fly-by of Saturn's
    largest moon Titan - the closest ever performed.

    Read more:
    http://www.esa.int/SPECIALS/Cassini-Huygens /SEMB2E 0A90E_0.html

  11. Bad idea. by Anonymous Coward · · Score: 4, Funny

    What would the aliens think if they get a peace offering of music, only to get sued by RIAA shortly thereafter?

  12. good flavor by Striker770S · · Score: 4, Interesting

    it seems that everybody is looking at mars and wondering why are space program is not really doing too much. Its good to show the public the vast and very unique moons of the gas giants. I am looking forward to see if they are going to do a "fly by" on the moon with the completely water frozen surface, orbiting jupiter (or maybe it was saturn). as long as NASA doesnt screw up and place anything backwards or messes up on unit conversions, then they have my support again!

    --
    I thought what I'd do was, I'd pretend I was one of those deaf-mutes. - Catcher in the Rye
    1. Re:good flavor by red+floyd · · Score: 2, Informative

      n the moon with the completely water frozen surface, orbiting jupiter (or maybe it was saturn)

      Europa, the second Galilean moon (Io, Europa, Ganymede, Callisto).

      --
      The only reason we have the rights we have is that people just like us died to gain those rights. -- Cheerio Boy
  13. Also sampling Titan's atmosphere... by jangobongo · · Score: 4, Informative

    Not only will the Cassini be taking pictures, but its ion and neutral mass spectrometer will "scoop up" and sample Titan's atmosphere as it passes at a distance of 1,200 kilometers (745 miles).

    "One important goal of this flyby is to confirm scientists' model of Titan's atmosphere to prepare for the Huygens probe descent," according to this article at SpaceDaily.com.

    --

    Sig cancelled due to lack of interest
  14. Titanian? by commodoresloat · · Score: 3, Funny

    Yes but rumors will spread like wildfire on the Titanian internet. Which the Titanians will be browsing with their Apple Titanian powerbooks.....

  15. raw images by Anonymous Coward · · Score: 4, Informative

    The raw images may be higher resolution but guess what....they are also "raw"! That means they haven't been processed yet. The image data isn't very useful unless you have the necessary parameters / algorithms to process the data.

    There will be several steps in processing the image data, bad pixel correction (I guess these CCDs should have very few); white/black balance; tonal / grey calibration; others? I'd be surprised if there weren't a few others.

    I guess the white/black balance is the most important thing I mentioned ....responsiveness accross the CCD won't be the same and must be compensated for. I don't know if they've got a seperate grey calibration step (you'd need calibration data to reproduce it)....you could fiddle with tone curves yourself to make stuff pleasing to the eye / see different stuff.

    Can anyone supply more details on the calibration?

    So far as I know it's not worth downloading the raw images unless you want to exercise some bandwidth....I think that Nasa might give out the calibration data to some people (remember British scientists discovering possible new moon?)....Anyone know all the ins and outs?

    1. Re:raw images by H01M35 · · Score: 3, Informative
      From the FAQ
      Why does the contrast look different between images?

      The camera measures light from an object at each point in an image and assigns it a number from zero to 4095 depending on its brightness. Sometimes the scientist can't afford to send this amount of data for each pixel because of the amount of storage it takes. The camera has the ability to convert this range of values to those from zero to 255. The camera does this according to a preset table of values designed by the scientists. This table devotes many of the 256 levels for less bright things and less levels for brighter pixels. Part of calibrating an image on the ground is to reverse this table and get back pixels in the range of zero to 4095. Because you're looking at the raw data, images sent back in this mode will have dimmer things look brighter compared to the brighter parts of the image than in images not in this mode.

      Why does the image look bizarre/psychedelic?

      As in the previous question, the other way the camera can send back less data (by sending pixels with values from zero to 255 instead of zero to 4095) is to send back only the lower binary digits of the number. This is like having a list of amounts of money and only recording the amount of cents for each one and assigning the brightness in an image to the amount of leftover cents. Pixels with brightness values just under 255, like amounts just under a dollar, will appear almost white, while pixel values just over 255, like amounts just over a dollar with not many cents, will appear dark. The ideal use of this mode is for image scenes that are dark with almost all of the pixel values less than 255. If the scene is simple with gradual increases in brightness, then even if the original values get over 255 and go dark again, the scientists can figure out what the real value was. If the scene is very complicated or the original values are much brighter than 255, the image can have many bright and dark transitions with strange contours. In this case, the image will look very bizarre but not have much scientific value.

      Seems like they want more detail in the dimmer areas. There's also an interesting look at the filter combinations that they can use.
  16. Life on Europa? by CRepetski · · Score: 2, Informative

    A flyby of the second Galilean moon could prove to be especially beneficial, as it has some of the most favorable conditions for life (or past life) in our solar system.

  17. I want my Goop! by Tablizer · · Score: 3, Interesting

    This is cool. It is a map pointing out where the lander is targeted. The map was made from prior flybys and also shows where today's mission is to image.

    If the dark stuff really is liquid goop, as some speculate, I wish they would target a little to the north to land right in the stuff and float. I would much rather see images from floating on a lake of goop than yet more rocks. We got enough of rocks from Mars, Venus, the moon, and Eros. Time for liguid landings. Please NASA, retarget for the sake of Goop!

    1. Re:I want my Goop! by Tablizer · · Score: 2, Interesting

      They've done some preliminary image processing. Here is an example. Notice the crisp boundaries in the third image. It looks just like a water (liquid) boundary. Dust or rocks rarely have such distinct boundaries of color for this much area. This adds to the hydrocarbon lake theories. This is so cool!

      However, it still means that the probe may land on an oval-shaped island (matching it with the prior map), which would be a bit of a disappointment, as described above. NASA, please target the damned liquid! The probe is designed to float.

  18. Holy Shit!!! by Thaidog · · Score: 4, Funny

    It's the death star! Red Alert!
    http://saturn.jpl.nasa.gov/cgi-bin/gs2.cgi ?path=.. /multimedia/images/large-moons/images/image17.jpg& type=image

    --

    ||| I still can't believe Parkay's not butter.

  19. Mod me troll but... by macz · · Score: 2
    There comes a point when I hope that robot spacecraft like this fail and the logical conclusion is that "Well... I guess we will have to send people."

    I am glad that our knowledge is expanding by orders of magnitude, but inwardly I long for a vast open ocean (of space) being the only thing separating us from a "new world" where we can go, colonize, and spread the virus of humanity before we kill ouseleves living in our own filth.

    Naturally it will be a robot that finds this new world first, but there is just some atavistic, medieval reaction to the idea that a robot is our emmisary to the stars.

    --
    ...But I digress. TREMBLE PUNY HUMANS!ONE DAY MY SPECIES WILL DESTROY YOU ALL!
  20. You guys fried their new supercomputer! by iamlucky13 · · Score: 2, Interesting

    NASA just finished building their new supercomputer, and it's already been slashdotted. Actually, the second try worked, but the first one gave me a server busy message.

    The NASA TV feed is pretty interesting. They just went through a series of photos from one of the cameras taking shots at different wavelengths which very dramatically displayed the effect of wavelength "windows." They also mentioned that they sampled the upper atmosphere on the way through, so maybe there will be something interesting to tell as a result of that.

  21. Re:Really Glad NASA didn't screw up this one!!!! by Silverlancer · · Score: 2, Informative

    Not exactly. Cassini isn't the first mission to use a nuclear power system first of all, and second of all if it did explode there would be no explosion and the radioactivity would be spread so much that it would be lost among Earth's background radiation. Read up before you comment.