Harry wrote:andersa wrote:I thought the idea was to use radio telescopes on Earth to try to pick up the faint Huygens data signal as a backup measure just in case the there were still problems with the Cassini relay operation
AFAIK this was never planned. It's just a way to quickly check that Huygens is/was alive.
The carrier signal is also analyzed using interferometry, to determine the precise descent path of Huygens through the atmosphere. I wasn't aware of this experiment until recently, so I guess I must have misread something about it earlier in connection with the Cassini relay doppler problem, thinking the radio telescopes were for data backup.
I also watched the ESA press conference (via NASA TV webcast) where Huygens mission manager Lebreton explained they had been surprised by reports from Australia that Huygens just continued transmitting, and they were now busy requesting time on radio telescopes also in Europe to continue receiving the signal as Saturn rises in the night sky (Saturn is currently in opposition). The batteries on Huygens are told to last for up to seven hours under optimal conditions, which means they have probably run out by now.
There were several questions from the press about the redundancy of the data channels. As I understand it, the carrier signal from the A channel was supposed to be used to obtain additional interferometry data. That opportunity may now have been lost, if the A channel failed as has been indicated. While all instruments onboard have been made to deliver their data via both A and B channels, they haven't spent valuable time transmitting every picture twice, but instead twice as many pictures, half of which may now be lost. Given that they will largely show the same piece of ground, this is hardly a disaster, just less redundancy in the data.
First pictures are expected to be made public around 19:45 GMT (11:45am PST).