How could Nixon have spoken with astronauts on the Moon in 1969 on a telephone 240,000 miles away, through the Van Allen belt?
The telephone Nixon was speaking into was relayed to a radio transmitter, which was connected to a very large dish antenna , most probably the one at Honeysuckle Creek in Australia, although it could have been Goldstone in California or Parkes in Australia. Here is a diagram of how the signals were sent and received. The diagram shows the the signal route for the TV signal, but as they were all combined with radio, engineering data, bio data, tracking, etc. all in one radio signal called the Unified S-Band it is also valid for telephone calls on the radio voice link. Graphics -NASA..Note the positions of the Australian sites are not accurate..see comments below, from David Charles. Also the INTEL satellite signal went to New York before distribution to the networks.. Here is a photo of the dish antenna at Honeysuckle Creek it is 26 meters in diameter, or 85 feet. This is similar to the other tracking antennas. The radio voice signal was split into two different frequencies, this is called "duplex" which means that both ends could talk and listen at the same time, no need to stop and release the transmit button on your microphone ,or say "over". Although it was still difficult because of the 1.5 second delay caused by the distance to the Moon. EDIT: Scott Obrien suggested an addition as an edit. Which I have also edited and added to using the Honeysuckle creek site as my source. Thanks Scott. The Manned Space Flight Network The backbone of this communications network is the NASA MSFN (Manned Space Flight Network). Three 85 foot (26 metre) stations were built for communication at lunar distances. Each was teamed with a nearby 85 foot Deep Space Network antenna for redundancy and versatility. In addition, a series of 30 foot (9 metre) USB antennae were established around the world, as well as tracking ships and the ARIA fleet of KC-135 aircraft for critical support in earth-orbit, at TLI and during re-entry. The MSFN (generally pronounced "misfin" in the US and M-S-F-N in Australia) was managed by the Goddard Space Flight Centre, in Greenbelt, Maryland. An amazingly sophisticated voice and data network, NASCOM, centred on Goddard, brought the MSFN together. All communications from Houston went via Goddard. then to NASA mission control at Houston, NASA launch operations at Kennedy, NASA JPL at Huntsville Alabama they were all linked by hundreds of thousands of copper phone lines and undersea cables . So patching the presidents phone in to the network was a trivial task. Here is a map showing the tracking station coverage.. From Honeysuckle Creek site. The Van Allen Belts are not a barrier to radio signals. There are many communications satellites and television carrying satellites in a geosynchronous stationary orbit, many thousands of miles beyond the VABs, Which, if you have satellite TV, is the reason you don't have to keep adjusting your antenna all the time. If the VABs stopped radio signals most of our international communications would be blocked as would all satellite TV. |
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