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 travelling faster than the speed of light in a given medium What was this Cherenkov detector used for? It doesnt 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?