How was it possible for astronauts to send back tv/radio signals to earth from the moon? I have just been teaching my son about waves behavior and understand that radio waves are reflected back to earth from the ionosphere. As far as I know microwaves were not used for communication purposes back then. How did the Apollo team then manage to send TV/ Radio signals back from space?
It can be seen through this Wikipedia article that all communication with the Apollo missions was done at about 2.2 GHz, which is well above the frequency that reflects on the Ionosphere (No higher than about 30 MHz).
FYI, the Gemini radio system also used frequencies in the UHF range, although it included some VHF, and even some HF. The HF/ VHF signals were either used for voice communication, or nearby operations (Recovery, acquisition). HF was more used then than it is today, and allowed for somewhat of an over the horizon effect. Depending on propagation, it can be difficult, but the 15 MHz used has minimal interference.
Microwaves are considered those with a higher frequency than 300 MHz, so technically, they did use microwaves for the Apollo program. These signals work great to penetrate the atmosphere.
http://novosti-kosmonavtiki.ru/mag/2005/1045/24532/ image of the Earth rising above the lunar horizon, taken on a television channel from one of the Apollo, intercepted by the Soviet tracking station in Crimea ("Shkolnoye").
1 Unified S Band 2.1 Ghz TV Signal / Voice / Telemetry / Medical Moon to Earth / Earth to Moon <*
2 Two UHF Frequencies 225-380Mhz band used on the moon <*
3 Various radar 8.1 Ghz
4 C-Band 5.6 GHZ
5 2 x Intelsat Satelites for round world & USA TV coverage
6 890mhz tracking