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Space Science

Huygens Probe Lands on Titan 686

Posted by michael
from the we-get-signal! dept.
WillDraven writes "CNN, NASA and the ESA are reporting that the Huygens space probe has entered the atmosphere of Saturn's moon Titan after traveling 2.2 billion miles. Pictures from the moon's surface should be available sometime this afternoon" according to the NASA TV schedule. What we know so far is that Huygens landed successfully and sent at least the carrier signal from the surface to Cassini for 90+ minutes, more than expected, and that Cassini has successfully repointed at the Earth and begun relaying the data it received, beginning with test packets. Huygens now sits on Titan, silent forever, while we wait to see whether or how much valuable data Cassini obtained and can send back. Update: 01/14 17:20 GMT by M : So far: they report zero lost packets in the transmission, but one of the two independent data-collection systems is apparently giving some problems. Update: 01/14 21:40 GMT by J : The news is pretty much all good: a very successful mission. Expect to see many photos within hours, but for now apparently only three have been released. Ice blocks or rolling stones -- let the debates begin!
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Huygens Probe Lands on Titan

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  • Any pics yet? (Score:5, Interesting)

    by FortKnox (169099) on Friday January 14, 2005 @12:22PM (#11362569) Homepage Journal
    I know it'll be a while, but I anxiously await the pictures and the sound (yes, they have a mic onboard). I guess it'll mostly be hissing, but it'll be interesting to HEAR a distant planet (one whom has a thick and nasty atmosphere).
  • Pronounce Huygens (Score:5, Interesting)

    by awhoward (108214) on Friday January 14, 2005 @12:30PM (#11362699) Homepage
    If you want to know how to correctly pronounce Huygens, go to this web site [].
  • Re:Any pics yet? (Score:4, Interesting)

    by Lusa (153265) on Friday January 14, 2005 @12:31PM (#11362727)
    The sound of the impact is the one I'd like to hear, be it squelch, splash or boom.
  • expensive data... (Score:2, Interesting)

    by dynamo_mikey (218256) on Friday January 14, 2005 @12:33PM (#11362748)
    Wow, that was expensive for so little data. So now Huygens is just a very expensive popcicle?
  • Re:For the record... (Score:5, Interesting)

    by justanyone (308934) on Friday January 14, 2005 @12:40PM (#11362855) Homepage Journal

    NASA really has something to learn about broadcasting. There are frequently long sections of:
    * dead air;
    * video with no sound, typically of big rooms with people milling about;
    * sound with no picture, people talking over a picture of NASA's logo;
    * video with "cocktail party" sound, where someone abandons the mike on a filing cabinet and you get to hear people walking by saying "Great weather today, Dave!"
    * unscheduled time with a NASA logo and no clue when the next broadcast is.

    Kind of frustrating. Of course, there's the crowd that says, "don't complain, at least we have pictures!", but I'd really like a little higher production values.
  • it makes you wonder (Score:2, Interesting)

    by iamchaos (572797) on Friday January 14, 2005 @12:46PM (#11362934)
    Huygens now sits on Titan, silent forever

    Will anyone, or anything, ever see it again. This expensive contraption sits silently on the surface of a frozen moon, billions of miles away, while we move on with our everyday activities. Kind-of surreal.

  • pins and needles (Score:5, Interesting)

    by dAzED1 (33635) <brianlamere AT yahoo DOT com> on Friday January 14, 2005 @12:46PM (#11362944) Homepage Journal
    Here's the log from the ESA's site []. Its in UTC - so we're talkin 23 minutes ago....such a wonderful thing to look forward to

    16:20 First data received from Huygens probe

    15:26 Confirmation received that Huygens probe data was successfully communicated to the Cassini spacecraft

    15:00 First Huygens probe data expected at around 16:00
    Probe life has now been over 5 hours

    14:10 Playback of probe data begins
    Ground control confirms that a signal is still being received on Earth from the Huygens probe, suggesting its batteries lasted well beyond the minimum design limit of 2 hours 15 minutes

    13:47 Cassini Orbiter has been turned in its orbit to poin the high gain antenna towards Earth

    12:30 Confirmation given of signal tracking for at least 2 hours

    11:24 Estimated time of surface impact and end of the descent phase

    11:23 Descent lamp activated to provide ground reflectivity measurements

    11:12 Cassini spacecraft undergoes closest approach to Titan passing at an altitude of 60 000 km at a speed of 5.4 km per second

    10:30 Green Bank 110 m telescope confirms a carrier signal from the Huygens probe.
    Signal indicates that the probe has survived the entry phase and that the instrument payload is active.

  • by Anonymous Coward on Friday January 14, 2005 @12:50PM (#11362997)
    Your post reads like some rambling blog entry.

    Actually, it is his blog entry. See the guy's webpage: []. He just cut and pasted something he had already written into a comment and let loose. Of course since it insulted a disliked group, hippies, instead of offering a rational argument, it gained a +5 forthwith. Welcome to /.
  • Photojournal (Score:2, Interesting)

    by cy_a253 (713262) on Friday January 14, 2005 @12:54PM (#11363049)
    To hold you up until the first lander pictures are in, here's every image ever taken of Titan by NASA probes. []
  • Re:For the record... (Score:4, Interesting)

    by Waffle Iron (339739) on Friday January 14, 2005 @01:01PM (#11363198)
    NASA really has something to learn about broadcasting.

    It's better than it used to be. I remember watching live moon landing coverage when I was a kid. It was comprised largely of long stretches of fuzzy black-and-white blurs, static, radio beeps and barley decipherable garbled voices. All of that did give the coverage a cool alien feel, though.

  • by peter303 (12292) on Friday January 14, 2005 @01:08PM (#11363337)
    Scientists are holding tight whether they good telemetry from the probe. The ESA designers forgot [] to correct for the doppler shift of the changing velocity between the Huygens probe and the Cassini mother ship. There is a chance that some of the signal could shift outside of the attenna frequency range and be lost. The landing was changed to slower trajectory orbit to hopefully compensate.
  • by Rei (128717) on Friday January 14, 2005 @01:13PM (#11363434) Homepage
    Uh oh [].

    "NASA and the scientific community are considering adding a Europa lander to JIMO. The high-tech lander could make on-the-spot surface observations at the Jovian satellite. Europa is thought to harbor an ocean under its icy crust."
  • Re:Congratulations.. (Score:1, Interesting)

    by Anonymous Coward on Friday January 14, 2005 @02:23PM (#11364646)
    Here's an interesting story about one guy who helped make it happen: /oct04/1004titan.html []

    And about the Italian company that screwed up part of the transmission system in the first place (and who couldn't even be bothered to comment on the story because they were all off on summer vacation).

    Che incompetenti!
  • Sad State of Affairs (Score:3, Interesting)

    by HungWeiLo (250320) on Friday January 14, 2005 @02:29PM (#11364757)
    The online CNN poll, albeit very unscientific, shows that 33% of respondents think the Huygens Probe was a waste of money.

  • by egomaniac (105476) on Friday January 14, 2005 @02:35PM (#11364873) Homepage
    Quote from Nasa's Huygens site ( huygens.cfm []):

    Much of the battery power will be used to power the timer for the 22 days of "coasting" to Titan.

    So, while I agree with you that a timer should essentially be "free", apparently there's more to it than that.
  • by cybrthng (22291) on Friday January 14, 2005 @02:57PM (#11365238) Journal
    Wrong on both accounts. The russians new the temperature on Venus just as we know the temperature on Titan. We can use a plethora of scientific instruments to do chemical, compound and atmospheric analysis on the planets and get very good temperature results.

    Russians used Venus landers to prove it could be done - they built in cooling units and such to last as long as possible.

    The pictures, while low res are an awesome site to see for Venus, so here's hoping to some crazy pictures from titan.
  • by dtolman (688781) <> on Friday January 14, 2005 @04:41PM (#11366609) Homepage

    And not only that - for the first time all the rocks aren't angled or jagged. They are all rounded. So that means lots of liquid erosion. Plus they are sunken into the ground - that means we landed in a really liquid rich environment.

    Maybe the shoreline of some Titan lake/ocean at low tide?

  • Re:Pathetic! (Score:1, Interesting)

    by Anonymous Coward on Friday January 14, 2005 @06:24PM (#11368195)
    It took over seven years for this ground-breaking mission to reach its destination. The probe spent over two weeks tumbling towards Titan's atmosphere. It spends two hours parachuting down to the moon's surface and another 90 mins "talking" to Cassini. Cassini then has to send back the (potentially corrupt) data and it has to get relayed to the ESA guys. Then they have to set all their data reduciton/processing routines at work, none of which will have been properly field tested due to the unpredictable nature of the telemetry.
    And back on Earth sits Mr Bender, feet up on his desk, coffe in his hand, bitching because the ESA guys won't put out a pretty picture in under five minutes.
    You may be a scientist on paper, but you are not a scientist at heart.
    --Mr Anonymous Jackass
  • Here's what gets me (Score:4, Interesting)

    by i41Overlord (829913) on Friday January 14, 2005 @07:18PM (#11368783)
    I could understand if they just didn't have the time to put up the pictures yet, but that doesn't seem to be the case here. NASA had some of the pictures up on their website a little while ago, and the ESA made them take the pics off.

    So it seems that they don't have time to put the pictures up on their site, but somehow they do have the time to tell those who already did post the pics to take them down.
  • Re:Pathetic! (Score:4, Interesting)

    by multiplexo (27356) on Friday January 14, 2005 @08:20PM (#11369351) Journal
    There's an interesting article [] on the lameness of the ESA presentation at Space Daily [].

  • Re:Pathetic! (Score:2, Interesting)

    by Honken (665599) on Friday January 14, 2005 @08:47PM (#11369654)
    I find this whole thing very exciting and is more than happy with three good pictures at this stage. There are some more images here: s_050114.html [] , but they're really not much to look at, so I prefer to get nicer ones later on instead of raw image data that you really cannot make anything out of anyway...

    When the first Cassini images arrived I made a big thing about it at work, which was kinda stupid since the first raw data really did not look like anything of interest, so people did not really care about it at all after a couple of minutes. These three images on the other hand are really great, so I believe people will find them a lot more interesting.

  • by stuktongue (140376) <adam DOT grenberg AT gmail DOT com> on Friday January 14, 2005 @08:47PM (#11369656)
    Thanks for this. Working in the space business (I work at Boeing Satellite Systems as a comm engineer), I find this subject particularly interesting. Having read the IEEE Spectrum article, let me (hopefully) clarify for the layman what I think happened....

    Changing range between the Cassini orbiter and the Huygens probe with the original mission trajectories would lead to Doppler shift of the signal from the probe to the orbiter. This shift either compresses or stretches the incoming signal in time, depending on whether the two are closing or moving apart. To accommodate this, one must, at a minimum, design the orbiter receiver's phase-lock loop (PLL) so that it has sufficient bandwidth to track the modulated carrier at it's shifted frequency.

    If this is done (and it was), the receiver can lock on to the signal and demodulate it, retrieving the baseband signal as an analog waveform of voltages corresponding to 1's and 0's (BPSK, or binary phase shift keying--the modulation scheme used for the Cassini-Huygens data link--is a very basic digital modulation scheme and is relatively easily demodulated). This signal must then be processed by a bit synchronizer, which looks for voltage transitions (corresponding to individual bits) at specified intervals according to the design data rate. Here is where the problem appears to have crept in.

    The nominal data rate for the Cassini-Huygens data link is 8192 bps. However, the Doppler shift that alters the carrier frequency doesn't alter it in isolation; the entire wave is compressed or stretched. As a result, the transitions between 1's and 0's are compressed or stretched in time, as well. Apparently, Alenia Spazio SpA, the Italian company that manufactured the Cassini-Huygens data link equipment, hard-coded (in firmware, not software) the bit synchronization processing to work at 8192 bps, with only a small tolerance for variation in data rate. The variations in data rate expected due to Doppler shift would have exceeded this design tolerance, causing the bit synchronizer to identify 1's and 0's incorrectly (producing gibberish).

    Fortunately, due to the efforts of the Swedish engineer who discovered and spearheaded the look into the problem, and the rest of the ESA/NASA team, the problem was detected and a workaround was devised. By altering the trajectory of Cassini, the Doppler shift could be minimized and the system could be made to work within its design. At least that is the hope.

    For all you open source advocates out there, it is further interesting to note that a contributor to this problem going undetected for so long was Alenia Spazio SpA's unwillingness to disclose the specific design details of their radio to the ESA/NASA, who might have detected the problem earlier on. Compounding the problem: apparently, an NDA could have been arranged, but it was largely deemed unnecessary due to the supposed simplicity of the radio design problem. Caveat emptor!

    All quite cool, really.

An age is called Dark not because the light fails to shine, but because people refuse to see it. -- James Michener, "Space"