Teo Gibson, via Facebook asked:
Why do ships lose contact when they're entering the atmosphere?
If you have a high speed entry, you create a pocket of ionised gas around your probe. The gas is heated up so much, it becomes ionised - itís stripped of its electrons. That is not transparent to radio waves, so you have a radio black out.
The same thing happens with vehicles re-entering the Earthís atmosphere. It used to happen with the shuttle I think and the Apollo vehicles. So thatís the main reason. Itís the state of the gas around a high speed probe.