Saturn Experiment Might Be Salvageable

komissar writes "The Seattle Times has a recent update on possible salvaging of the Atkinson Saturn experiment. With some work, the data may be recoverable."

Computational efforts required on Earth only?

[Anders Andersson]

I thought they were planning to use the radio telescopes for this (reconstructing the path of the probe) long before they learned that the Channel A receiver wasn't going to be operational. Or, what was that Very Long Baseline Interferometry experiment meant for? Merely detecting the presence of a signal?

I suppose that one advantage of doing the same measurements via two receivers (one on Earth, the other on Cassini) would be the ability to reconstruct the path in two dimensions, thereby learning not only how fast the probe travelled, but in what direction (sideways or down).

I guess most of that computational effort may be to properly extract the true signal from all the other noise they probably recorded, much like the SETI@Home project does in a distributed fashion. However, no amount of computation can properly compensate for the loss of a receiver listening from a different position, if that's indeed what the receiver onboard Cassini was meant to do. Even if they had a dozen radio telescopes on Earth listening simultaneously, they would all detect the same doppler shift, telling them essentially nothing but the speed of Huygens relative to Earth only. As it was close to mid-day where Huygens landed on Titan, the Sun (and Earth) were close to zenith, and we would primarily be measuring descent speed, not lateral speed.

Has anybody seen a scientific explanation of the details of the doppler wind experiment, such as what measurements the Channel A receiver was supposed to perform and how it would deliver its results to Earth? I'm pretty sure three hours of analog recording of a high-frequency carrier wave would constitute way too much raw data to transmit to Earth for later analysis, so I assume some processing must be performed already onboard Cassini. If so, performing the same process for the signal received directly via the radio telescopes shouldn't take considerably longer time, once it has been properly extracted from the noise.

I disagree with your reading of TFA

[MarkusQ]

The head of the space probe mission to Titan said today that much of the data from a botched experiment designed by a University of Idaho professor was recovered by radio telescopes on Earth...Idaho scientist David Atkinson said that someone failed to turn on a radio receiver for the instrument he needed to measure the winds on Saturn's largest moon. Because of that error, data transmitted by the gear on the Huygens lander was not received by the Saturn-orbiting Cassini spacecraft for relay to Earth.

It sounds to me like they were able to receive the data from Earth, without needing to have it relayed by Cassini. It doesn't say anything about them attempting to reconstruct the path from here, but rather that they picked up the data transmitted by the wind-speed instrument directly.

--MarkusQ

This is not clear..

[adeyadey]

Does anyone know if they are trying to actually retrieve the A-channel data, or are they just analysing the carrier for dopler-shift to get the data for this experiment?

Its an important difference - if they can retrieve the A-Channel data, they can re-generate the lost picture data from that channel too..

how did they know to start listening?

[menscher]

Silly question, but at what point did they realize there was a problem? If they didn't find out there was a problem until after failing to receive channel A data from the orbiter, then the radio waves from the probe would have already passed the Earth also.

Did they somehow know that they'd forgotten to flip the switch before any data was transmitted?

Or maybe the transmit time was several days, and they only missed the first few hours?

Just trying to make sense out of this, since the journalists obviously don't have a clue. Hopefully someone who worked on the project can respond.

Why only one chance at transmit?

[Vellmont]

I tried a few days ago, but couldn't find much information on the design of the Huygens probe. One thing I don't quite understand is why they only planned to transmit the data once, then leave Huygens for dead? Is it because of the extreme cold of the planet and they couldn't prove enough heating + insulation, or were there other factors involved? The vaccum of space is rather cold too, but electronics seem to work OK.