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Huygens Wind Experiment Salvaged
SeaDour writes "Earlier, it was reported that the data from a critical wind speed experiment onboard the Huygens probe to Titan was completely lost due to someone forgetting to turn on one of Cassini's communications channels. However, it now appears that ground-based radio telescopes from the National Radio Astronomy Observatory were able to record the transmission's many subtle doppler shifts and reconstruct that lost wind data. The winds altered the probe's horizontal rate of descent, thereby producing a change in the frequency of the signal received on Earth. Additionally, the resolution of the radio telescopes was good enough to track Huygen's position to within one kilometer, allowing for the creation of a three-dimensional model of Huygen's descent."
... nothing like a little backup.
*yawn*
is that if that experiment would have been turned on like it was supposed to, probably nobody here would have ever known that it existed in the first place. ;-)
How can you have a horizontal rate of descent? Was this thing was falling sideways?
What a strange and fantastic world this Titan must be.
.
I hope it's not making a habit that people can forget something and fix it later, it doesn't work every time.
Rock that crushes, Paper & Scissors that don't matter.
That we have equipment sensitive enough to track a probe's position to within *1* km all the way out on Titan..
saying it seems rather bland but when you think of how many millions of miles away it is, I think it's pretty remarkable.
...the scientist who forgot to switch the experiment on, making "wooshing" sounds into a mike. "We got the data back, nothing to be embarassed about here, no sirree!"
if anyone at nasa is dumb enough to read slashdot : you guys rock !
Seriously : most people would give up, blaming someone else. It takes a true fighting spirit to try and recover from what someone else has fucked up.
When will I end this grieving ? When will my future begin ?
that's the first diagnostic question I always ask when fixing something.
Like Sweepstakes? Try out my service @ http://www.yourpowersweeps.com -- Free 21 day trial, no cc needed.
So basically what they are saying is they should have used the space for some other experiment? The guy spending years setting up an experiment that never got turned on isn't as bad as designing a useless experiment taking up space on the probe. Or was the onboard experiment supposed to be much more accurate?
I Am My Own Worst Enemy
The second channel was not a redundant channel. Channel 1 was for the major data. Channel 2 was for half the total images uplinked to Cassini. Channel 2 was also dedicated to the Doppler data.
Someone failed to turn on the receiver on the Cassini device. The data was transmitted on channel 2, just never received by Cassini.
Over and out
So.... it was on?
Anyone else a bit puzzled?
Technology, the cause of and solution to all of life's problems.
So, the experiment itself wasn't saved. They just found another way to get the data (reading the doppler shift in the signal).
So, here's a good question: why did they need to include the equipment for the experiment in the first place?
From the very beginning it was reported on here that ground based telescopes would be able to record and reconstruct the data.
This is the first time that I heard them saying that the data was "completely lost".
They're quite old anyway, basically from the day after it landed. For example mentioned here.
Slashdot chose to post about the doomed mission instead, which made me believe it was indeed lost... but apparently it was like this all the time.
Beware: In C++, your friends can see your privates!
A lot of this work was done by the "Green Bank Telescope" aka the Great Big Telescope or GBT. You should check out the specs on this telescope. It is the world's largest fully steerable telescope and it is taller than the Statue of Liberty. I was a grad student while this was being built, and was always impressed when I saw presentations about the amount of work that went into creating this instrument. It is not nearly as famous as other telescopes like Hubble or Keck, but is very impressive nevertheless.
IIRC about half of the picures taken were relayed via the A channel and what we have seen is all B channel stuff only.
Any chance of reconstructing those images from the ground-based recordings of the A channel, or is the signal so weak that all that can ever be deduced is the carrier frequency, not any data?
earning karma in heaven right now....
talk about geek status points. The guy who figured that out must be strutting around like a fricken' god or something, or one of those guys in the movies who does the tap-tap-tap-we're in routine.
Post may contain irony: discontinue use if experiencing mood swings, nausea or elevated blood pressure.
Three people have responded to the original poster's question so far. The two who had a nickname attempted to answer his question while the anonymous coward was content to just be a smart-a$$.
Anyway, the article was, of course, referring to the horizontal *component* of the descent.
Don't take it personally DemiKnute...a couple of days ago I got hammered by a lot of AC's just for asking how you could take a picture of something 20K light-years away.
This is probably why "The Sims Online" failed as well.
A goal is a dream with a deadline
... of a maxim my team has tried to explain to our senior management many times, without sucess:
"Yes, we will always pull a miracle out of the hat for you when everything goes wrong. But, you should not write your plans with this as an assumption."
~~~~~ BigLig2? You mean there's another one of me?
The Star Trek:TNG writer's manual called for you to use the word TECH every time you needed a word like that; they got their science advisor to fill it in later.
So you really would see scripts with "Captain, I can compensate using TECH to TECH..."
I can't help but think that the series would have been better if TECH hadn't been such a cop-out. Sci-fi is about people, not technology, but often it's about how people interact with technology. If you don't know anything about technology then it's just the way people interact with mumbo-jumbo.
This hasn't gotten as much coverage, but a design oversight nearly cost all Huygens data. Doppler shift was not accounted for in the signal decode process. The mission plan had to be rewritten to find an alternative flight path that reduced the Doppler shift to within the limited acceptable tolerances. Fortunately, Cassini's approach to Saturn was accurate enough that enough fuel existed to allow this while preserving the latter part of the existing flight plan.
e /oct04/1004titan.html
Of course, in retrospect, maybe earth-based monitoring would have come to the rescue in this event, in an even bigger fashion.
"Titan Calling: How a Swedish engineer saved a once-in-a-lifetime mission to Saturn's mysterious moon"
http://www.spectrum.ieee.org/WEBONLY/publicfeatur
Sorry if this is a repeat. Slashdot's search 503-ed on me.
Perhaps you should RTFA, or perhaps even this article?.
1: The DWE consisted of two modules. One on Huygens, and one on Cassini. Without the activation of the Huygens module, we would have had no data for earth-based telescopes to detect.
2: The DWE carrier signal did double duty as a channel for image transmission. Not only did the receiver screw-up result in loss of DWE data, but it also resulted in the loss of 350 images as well.
3: Reception by Earth-based radio telescopes was uncertain at the time the DWE was designed. In addition, at the time the DWE was developed, it was thought that Earth-based radio telescopes would only be able to detect one axis of motion. The second axis of motion would have to come from the Cassini data.
Just to clarify, the "command" to turn "on" the oscillator for Channel A was not sent due to human error.
:)
Lager version at spacescience.ca
So that equates to no data sent to Earth from Cassini for that Channel which contains the wind data and half of the photos.
Channel B does not have a similar oscillator so it did not suffer from the same problem.
So my question is, what data did they get, (or could get potentially)?
Sounds like the photos will be lost because all they seem to have accomplished with the global radar conglomerate was a measurement of Huygens's Doppler shifting carrier wave signal.
This is probably not as accurate as the direct measurements but will give us a replay of the descent to within 1km thanks to some correlation to VLBI measurements taken on Earth also.
There is a heated debate between project teams going on in the background as to exactly where the probe landed.
So this data should do well to help pinpoint the location.
Because, I made up a collage, Titan's Huygens Collage
I'm interested in seeing more images. Knowing wind speeds is good data, but personally I'd much rather have more photos for my collage.