Cherenkov detector on a venus orbiter (Venera 9)

[hangainlover]

questions about the Soviet's Venus missions

I was reading about the Soviet Union's Venus missions and they equipped Venera 9 orbiter with cherenkov detector.
So it detects particles traveling faster than the speed of light in a given medium
What was this Cherenkov detector used for? It doesn't help them measure specifics of Venus as far as i can tell (temperature, atmospheric composition, pressure etc)

Also, for Venera 9 and 10, it says the landers were functioning fine. Yet they only were able to take data and have experiments on the surface of Venus for about an hour because the orbiter went out of radio range.
Did the orbiter go out of range because of the difference between Venus' rotatational angular speed and the orbiter's angular speed?

 

[Chronos]

Frankly, I think these missions were driven by a desire to discover new physics with potential military applications. It all makes sense in that context.

 

[Bobbywhy]

Venera 9’s Cherenkov detector was used to detect and count protons of Ep>500 MeV and electrons of Ee>7 MeV arriving from all directions.

http://nssdcftp.gsfc.nasa.gov/ spacecraft _data/russian_msu/venera-10/va_descr.txt