IN A NUTSHELL: Because it’s often edited out by documentary makers. To keep the narrative flowing, they often summarize or edit footage. That’s why sometimes in documentaries there’s no speed-of-light delay in Apollo’s Earth-Moon communications. But the delay is there in the unabridged reference recordings and transcripts published by NASA. Moreover, sometimes astronauts on the Moon replied before Mission Control had finished talking.
THE DETAILS: In some clips of the footage of the Moon landings, the astronauts appear to answer the radio messages from Earth too quickly. Radio waves, traveling at the speed of light, take about a second and a quarter to cross the gap between the Earth and the Moon, so there should be at least an equivalent pause between the words uttered in Mission Control in Houston and the replies from the astronauts on the Moon. If there’s no delay, the radio transmissions must have been fake, argue some conspiracy theorists.
But why would the hypothetical fakers have been so stupid as to forget to include the radio delay?
Indeed, these apparent anomalies have far less conspiratorial explanations.
Edits for timing and narrative purposes in documentaries
In documentaries, sound and footage are often edited for conciseness or pacing with respect to the original recordings. With very few exceptions, documentaries tend to omit unnecessary dialogue and use mismatched images to achieve a more dramatic and interesting narration by focusing on key moments. There’s no real intent to deceive, but the end result is that many documentaries are not as faithful as one might expect. The extent to which even award-winning films, such as For All Mankind, present inaccurately and misleadingly images and sounds of the Apollo missions is detailed by spaceflight historian James Oberg’s article Apollo 11 TV Documentary Misrepresentations (Wall Street Journal, 1994).
For example, the Apollo 11 lunar landing is often portrayed so that it seems that the very first words spoken on the Moon were “Tranquility Base here, the Eagle has landed”. Actually, if you go to the original recordings and transcripts (available at the Apollo Lunar Surface Journal website), it turns out that those famous words were preceded by a substantial chunk of technical reporting.
Here’s the unabridged transcript, starting from the very first contact with the lunar surface (Figure 9.7-1):
102:45:40 Aldrin: Contact Light.
Aldrin is telling Mission Control that the Lunar Contact warning light has turned on: this means that at least one of the 173-centimeter (68-inch) probes under the footpads of the Lunar Module has touched the ground. Technically, these are the first words spoken on the Moon.
Once the LM has settled on the surface, the series of technical status reports continues, as the spacecraft is prepared for its stay on the Moon:
102:45:43 Armstrong: Shutdown.
102:45:44 Aldrin: Okay. Engine Stop.
102:45:45 Aldrin: ACA out of Detent.
102:45:46 Armstrong: Out of Detent. Auto.
102:45:47 Aldrin: Mode Control, both Auto. Descent Engine Command Override, Off. Engine Arm, Off. 413 is in.
Only at this point does Mission Control speak out: Charlie Duke, future Apollo 16 astronaut, is working as Capcom for Apollo 11. He is one of the few people who talk directly to the crew in space:
102:45:57 Duke: We copy you down, Eagle.
102:45:58 Armstrong: Engine arm is off. [pause] Houston, Tranquility Base here. The Eagle has landed.
It’s quite obvious that these status reports are of no interest to the average viewer: that’s why they often get cut in documentaries.
Another frequent example of a cut for narrative purposes occurs seconds later: Charlie Duke, momentarily tongue-tied by the excitement of the event, mispronounces the new name of the Lunar Module, i.e., Tranquility Base.
He starts to say “Roger, Twan...”, then pauses and corrects himself: “...Tranquility. We copy you on the ground. You got a bunch of guys about to turn blue. We’re breathing again. Thanks a lot.” In most documentaries this flub is edited out.
Even the famous phrase “One small step for [a] man, one giant leap for mankind” is often presented in the wrong context for the sake of brevity: it’s usually heard as we see Neil Armstrong jump down the ladder of the LM. But actually, in the original video recording Armstrong jumps down and lands on the LM footpad, without touching the ground, describes his surroundings, hops up the ladder again (to test that he will be able to get back up at the end of the moonwalk), jumps down again, and only then does he cautiously place his left foot on the surface of the Moon and utter the historic words (Figure 9.7-2).
Conspiracy theorists persistently make the mistake of considering documentaries to be equivalent to official records. They are not; the only true reference material is constituted by the original raw data and footage.
Talking over each other
There’s also another even less dramatic explanation for the apparently missing delays: sometimes the astronauts on the Moon answered the first part of a message from Houston and then the voice from Earth continued talking, creating what sounds like an excessively short gap.
The astronauts also sometimes began speaking of their own initiative instead of responding to a communication from Earth and then Mission Control started speaking, giving the impression that the astronauts were answering and were doing so too soon.
Missing delay in Spacecraft Films DVDs
One objection raised by conspiracy theorists is that the Apollo mission DVDs produced by Spacecraft Films, which offer the unedited recordings of the astronauts’ lunar excursions and have been for years one of the most exhaustive reference sources regarding the Moon landings, sometimes seem to lack the expected radio delay.
These DVDs are an invaluable historical asset for anyone who wants to learn about the Moon landings, but they’re not perfect and they’re not official NASA productions (and today have been surpassed, in terms of completeness for some missions, by Ben Feist’s Apollo in Real Time website). The author of the DVDs, Mark Gray, is a private individual who gathered all the best audio and video recordings available at the time, from disparate sources, and assembled and synchronized them, trying to be as complete and faithful as humanly possible to the original events.
However, some inaccuracies in such a monumental work of documentation are almost inevitable. Clips that were recorded on videotape are mixed with recordings that were made on film, with separate audio tracks and therefore with all the audio-video misalignments that this mix entails. Moreover, the sources are analog media, which have natural speed variations and fluctuations both during recording and during playback. When merging sound clips from different sources it’s easy not to notice that the radio silence in one clip is not perfectly matched up with the silence in another clip. Most of all, this is irrelevant in terms of the experience of watching these DVDs.
There’s also the basic issue of synchronizing two audio sources (communications from Earth and communications from the Moon) that by their very nature have timing offsets that depend on the transmission time (at the speed of light) and on the equipment used, much as occurs nowadays with live sports broadcasts via satellite or on streaming channels, for example. There isn’t an absolute “now”; there’s no unifying timebase. Synchronization varies depending on where the spectator is.
Quite understandably, therefore, in the recordings on Spacecraft Films’ DVDs or in any other such work there may be moments when the sound is not perfectly synchronized with reality. But using this fact as proof that the Moon landings were faked is an error of method, because it fails to consider the far simpler alternative explanation and it doesn’t explain why the alleged fakers would forget to add the radio delay just here and there. Moreover, it clashes with all the other evidence that the Moon landings were real.
Rather ironically, sometimes conspiracy theorists themselves point out that another highly accurate technical source, the Apollo Lunar Surface Journal, also published the sound recordings of the moonwalks (without accompanying video) as part of its painstaking technical description of the activities of the astronauts on the Moon, and they note that these recordings have the correct delay. Their explanation is that the alleged fakers went back and fixed the missing delays after they were spotted. The more practical explanation is that the Surface Journal only published audio clips and therefore didn’t have to deal with the audio-video synchronization problems of DVD production.