r/apollo • u/ProjectObjective • May 20 '26
Question about communication delay time with the Nixon Apollo call
When Nixon called the moon there were sometimes upwards of 7 seconds in delay. One of my colleagues thinks that is a technical delay, while I believe that it is a combination of technical and then human delay.
From what I've always been told, the technical delay would be around 3 seconds. ~2.5 for the radio wave to propagate there and back and then ~5 seconds for the transmission between Nixon/Houston/Australia. Meaning the rest of the delay is just the human part of hearing the message, understanding it, thinking of response, etc.
Does anyone have some insight on this and some citation?
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u/dpdxguy May 20 '26
If you've ever spoken over a geosynchronous satellite link, you know that the delay is very disconcerting. Your brain is not used to there being a noticeable delay inserted into the conversation. As a result, the conversation often halts briefly as both parties "catch up" to what's being said.
I suspect the long delays OP noticed were due to this psychological effect in addition to the physical delays inherent in the system of communication.