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Unmanned Spaceflight.com _ Titan _ Real-time Telemetry From Lga?

Posted by: pioneer Jan 12 2005, 03:39 PM

I realize the real-time transmission of the probe data is not possible since the high-gain antenna will be pointed toward Titan to receive the data, but couldn't the low-gain antenna on the side of Cassini send a message to Earth indicating whether or not Huygens survived its descent throught Titan's atmosphere?

Posted by: djellison Jan 12 2005, 04:31 PM

Seing as you're going to know that 4 hours later by virtue of the HGA downlink - there would be no quantitative benefit - and the only qualitative beneift is to satisfy an impatient mind. It costs you r/f interference that may damage relay ops, and involves using spacecraft systems that dont have to be used. When you're doing everything possible to avoid a safing incident - thats not wise anyway.

Furthermore - it's hoped that a signal ( but no telemetry ) may well be seen from earth, of Huygens - and using multiple antennae a trajectory can be calculated from the doppler shift measured.

In conclusion - the only benefit in LGA ops during relay ops would be to satify understandable impatients. The drawbacks include increased chance of orbtier safing ( very bad), possible R/F interference ( bad ) and it's duplicating what's hoped to be done on earth anyway.

Doug

Posted by: pioneer Jan 12 2005, 04:45 PM

Thanks Doug.

QUOTE

it's hoped that a signal ( but no telemetry ) may well be seen from earth, of Huygens - and using multiple antennae a trajectory can be calculated from the doppler shift measured.

Wow

I didn't realize that was possible from such a large distance and a weak signal from Huygens.