Huygens Probe Prepares for Saturn Moon Landing 273
Nathan writes "A probe is about to land on one of Saturn's 35 moons, Titan. The probe is a collaboration with NASA, the European Space Agency and Italy's space program. The probe is apparently about the size of a Volkswagen Beetle. This landing should lead scientists toward new information about the atmosphere and the magnetosphere."
Timeline and (better) coverage... (Score:5, Informative)
It'd be worth staying up for, but the last time I did that, I jinxed the Mars Polar Lander.
If the Huygens timeline executes as planned, it will rank among the coolest engineering achievements in history. It will also have happened thanks to one guy who kept his eye on the ball [ieee.org] when nobody else was paying attention.
Here is a Countdown (Score:5, Informative)
In the application, you can also fastforward and see what Cassini does in the coming years.
For those interested in discussing this on irc (Score:5, Informative)
This channel is devoted to discussion of space science, current, past and future space missions.
This channel is frequented by a lot of knowledgeable folk. And please keep the discussion on topic
Y
Not NASA. (Score:5, Informative)
And NASA's Mars rovers are still going strong, whereas the ESA's Beagle is just a crater.
Re:35 moons! (Score:4, Informative)
Like the Pluto/Chiron? [nasa.gov]. Closer ration than Earth/Moon. [nasa.gov]. So there is a closer ratio example in *our* system.
Hypothesis are suppose to educated guesses based on *current* knowledge. Thus, you are not hypothesizing, but just guessing.
Re:Timeline and (better) coverage... (Score:4, Informative)
"In short: Cassini is at Saturn, and about to launch the Huygens probe into Titan's atmosphere (splashdown 14th January 2005). The communication link between Huygens and Cassini was not thoroughly tested before launch. Some thoughtful engineer realised this might be a problem, and after some pushing against resistance, managed to test Cassini's response to how they expect the signal from Huygens to look. Surprise suprise, Houston we have a problem. Turns out, the original engineers took account of doppler shift in the carrier wave, but not in the encoded data. D'oh! Problem is encoded in firmware, can't be fixed after launch. Double d'oh! So instead, they've altered Cassini's trajectory to eliminate the doppler shift. Hurrah for Boris Smeds!"
http://gimbo.org.uk/archives/2005/01/boris_smeds_
But Not ESA Either (Score:5, Informative)
More coverage: NASA TV and Planetary Society blog (Score:3, Informative)
It also looks like NASA TV will have live coverage [nasa.gov] for much of Friday. You can access their video and audio streams here [nasa.gov].
Re:Timeline and (better) coverage... (Score:4, Informative)
It's a real shame that the private Italian subcontractor didn't allow transparency in the plans for the transmitter. I mean, this is a SCIENCE mission, not a competition for profits. (The company viewed NASA as their competitor, and the transmitter as proprietary).
The board discovered that Alenia Spazio SpA, the Rome-based company that built the radio link, had properly anticipated the need to make the receiver sensitive over a wide enough range of frequencies to detect Huygens's carrier signal even when Doppler shifted. But it had overlooked another subtle consequence: Doppler shift would affect not just the frequency of the carrier wave that the probe's vital observations would be transmitted on but also the digitally encoded signal itself. In effect, the shift would push the signal out of synch with the timing scheme used to recover data from the phase-modulated carrier.
Because of Doppler shift, the frequency at which bits would be arriving from Huygens would be significantly different from the nominal data rate of 8192 bits per second. As the radio wave from the lander was compressed by Doppler shift, the data rate would increase as the length of each bit was reduced.
Although the receiver's decoder could accommodate small shifts in the received data rate, it was completely out of its league here. The incoming signal was doomed to be chopped up into chunks that didn't correspond to the actual data being sent, and as a result the signal decoder would produce a stream of binary junk. The situation would be like trying to watch a scrambled TV channel--the TV's tuned in fine, but you still can't make out the picture.
Alenia Spazio wasn't alone in missing the impact Doppler shift would have on the decoder. All the design reviews of the communications link, including those conducted with NASA participation, also failed to notice the error that would threaten to turn Huygens's moment of glory into an embarrassing failure.
Alenia Spazio's insistence on confidentiality may have played a role in this oversight. NASA reviewers were never given the specs of the receiver. As JPL's Mitchell explained to Spectrum, "Alenia Spazio considered JPL to be a competitor and treated the radio design as proprietary data."
JPL's Horttor admitted that NASA probably could have insisted on seeing the design if it had agreed to sign standard nondisclosure agreements, but NASA didn't consider the effort worthwhile, automatically assuming Alenia Spazio would compensate for the changing data rate.
Re:Not just images... (Score:2, Informative)
Re:Good luck! (Score:2, Informative)
www.esa.int (Score:5, Informative)
A 346 words article from India Daily is not the most relevant for an ESA project.
I hope
Re:Only a few hours until it makes a crater on Tit (Score:4, Informative)
Furthermore: "Alenia Spazio (the Italian contractor) wasn't alone in missing the impact Doppler shift would have on the decoder. All the design reviews of the communications link, including those conducted with NASA participation, also failed to notice the error that would threaten to turn Huygens's moment of glory into an embarrassing failure."
Get your facts right (although being AC, no doubt it was just xenophobic bullshit on your part).
Re:Only a few hours until it makes a crater on Tit (Score:2, Informative)
http://www.spectrum.ieee.org/WEBONLY/publicfeat
hint: it was a Swede working at ESA in Germany... so much about team play
Re:Timeline and (better) coverage... (Score:3, Informative)
I've got a copy of the ESA Bulletin journal from either January or February 1985 which was given to me years ago by a friend of the family - and one of the main articles is about the Huygens probe, in a form very similar to the final version launched in 1997. I think I ought to scan the article and post it online, just to give people an indication of how thoroughly planned these projects are. Unfortunately it's at home, and I'm in Brussels.
I was five years old when they had a detailed design for this probe. Now that's scary.
(Oh, and captain, we get signal! [spaceflightnow.com] Now just waiting for main screen turn on...
Re:35 moons! (Score:2, Informative)