Huygens Probe Lands on Titan 686
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!
Any pics yet? (Score:5, Interesting)
Pronounce Huygens (Score:5, Interesting)
Re:Any pics yet? (Score:4, Interesting)
expensive data... (Score:2, Interesting)
Re:For the record... (Score:5, Interesting)
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)
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.
iamchaos
pins and needles (Score:5, Interesting)
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.
Re:This all might not have happened (stupid hippie (Score:1, Interesting)
Actually, it is his blog entry. See the guy's webpage: www.jamesbrief.com [jamesbrief.com]. 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)
Re:For the record... (Score:4, Interesting)
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.
concern about signal quality (Score:4, Interesting)
Re:as long as we don't go to ALL the moons (Score:3, Interesting)
"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)
http://www.spectrum.ieee.org/WEBONLY/publicfeatur
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)
Re:Regarding the permanent silence of Huygens... (Score:3, Interesting)
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.
Re:Is it just me or ....... (Score:2, Interesting)
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.
Re:First photo from the surface of Titan!! (Score:3, Interesting)
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)
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)
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)
Re:Pathetic! (Score:2, Interesting)
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.
Re:concern about signal quality (Score:3, Interesting)
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.