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."

Comments

Things like that just amaze me...

[Dutchmaan]

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.

Re:Things like that just amaze me...

[kirkjobsluder]

I don't think it is quite that amazing. Radio telescopes appear to have a good enough resolution to image details of radio sources in remote galaxies. Identifying the relative position of an active source in our solar system would seem to be a less complex problem.

Do I understand this?

[nizo]

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?

Eh?

[SlayerofGods]

The probe was to transmit data on two channels, A and B, Atkinson said. His Doppler wind experiment was to use Channel A, a very stable frequency.

But the order to activate the receiver, or oscillator, for Channel A was never sent, so the entire mission operated through Channel B, which is less stable, Atkinson said. .....

Also, he said some of the Channel A signal reached Earth and was picked up by radio telescopes. "We now have some of this data and lots of work to do to try to catch up," he wrote.

So.... it was on?
Anyone else a bit puzzled?

Reading the doppler effect on the signal

[psyklopz]

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?

Re:Reading the doppler effect on the signal

[jwdb]

Actually, it was. Guess which signal they measured the doppler shift of - it was the data signal for this very experiment. The issue was that Cassini forgot to relay it, so they had to rely on the weak signal from Huygens itself.

Check out some of the other comments to this effect...

Jw

completely lost?

[i41Overlord]

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".

The GBT to the rescue

[spanklin]

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.

And the other 100s of imatges???

[Air-conditioned cowh]

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?

Teching the tech

[jfengel]

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.

Re:Horizontal rate of descent

[SuiteSisterMary]

If you remember from your high school graphing, y=mx+b; rise over run and all that.