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The Moon's distance can be as much as about 406,000 km from Earth. That's a round trip light time of roughly 2 x 406,000 / 300,000 = 2.7 seconds or more, depending on how the signal was relayed to mission control, plus any response time.

When the ascent module launched and accelerated vertically, how (the heck) did NASA get the video camera on the Moon to track it correctly several seconds in the future? Were clocks on the Moon and on the ground synchronized, or were they just anticipating based on verbal countdowns from the astronauts perhaps?

Or maybe they recruited Marvin the Martian to do the camera work?

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    $\begingroup$ Looking at the first video, the camera only starts panning upwards 2-3 seconds after liftoff. So it seems plausible to me that the operator only sent the command to start panning at liftoff, or just a little before. And it's not like they didn't have a nice countdown leading up to it. In general, the tracking really doesn't seem all that accurate; the ascent module barely stays within the frame. I suspect that, with a bit of simulated practice, it wouldn't be hard to manage that level of accuracy even with a 2.7 second delay. $\endgroup$ Jan 1, 2019 at 0:36
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    $\begingroup$ OK, I'm going to stay hands of on this one though. (I've muddied things enough already, I think) $\endgroup$ Jan 1, 2019 at 1:20
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    $\begingroup$ @AlexHajnal Stack Exchange is a strange animal and takes a while to get used to (I'm still not used to it). That's why my user profile says something like "Let Stack Exchange be Stack Exchange" ;-) In this case, the main idea is to get the most eyes to the best answers more than judging the details of the questions. update: However, I've just added "considering the substantial delay" to the title based on your concerns. Like (at)Hobbes says, SE is a collaboration. Thanks! $\endgroup$
    – uhoh
    Jan 1, 2019 at 1:26
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    $\begingroup$ @uhoh No, and your T-shirt is fine! I actually saw that it was your post after editing and wondered to myself if I just stepped on toes much bigger than mine. I love your questions as much as I love your answers! $\endgroup$
    – dotancohen
    Jan 1, 2019 at 9:26
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    $\begingroup$ @dotancohen it's hard to step on my toes as they are usually elsewhere and it was a correct and inevitable edit. $\endgroup$
    – uhoh
    Jan 1, 2019 at 9:30

1 Answer 1

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A controller on Earth, Ed Fendell, manually operated the camera by radio control, knowing the time of liftoff and the ascent trajectory expected and referring to a time-and-angle chart without watching the video feed in real time! According to Fendell:

Now, the way that worked was this. Harley Weyer, who worked for me, sat down and figured what the trajectory would be and where the lunar rover would be each second as it moved out, and what your settings would go to. That picture you see was taken without looking at it [the liftoff] at all. There was no watching it and doing anything with that picture. As the crew counted down, that's a [Apollo] 17 picture you see, as [Eugene] Cernan counted down and he knew he had to park in the right place because I was going to kill him, he didn't — and Gene and I are good friends, he'll tell you that — I actually sent the first command at liftoff minus three seconds. And each command was scripted, and all I was doing was looking at a clock, sending commands. I was not looking at the television. I really didn't see it until it was over with and played back. Those were just pre-set commands that were just punched out via time. That's the way it was followed.

The camera was mounted on the Lunar Roving Vehicle and was used during the EVAs to look at interesting things here and there -- essentially a third set of eyes in the field!

The LRV and its remote-controlled camera was flown on the last three Apollo missions, and only the third really got a satisfactory video of the ascent.

No attempt was made to track the ascent on Apollo 15 due to a mechanical problem with the camera.

On Apollo 16, it was difficult to pan fast enough to catch the ascent because the LRV was parked closer to the LM than on 17.

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    $\begingroup$ Wow. And here I assumed automation via local radar. Overestimating early 1970s technology apparently... $\endgroup$ Jan 1, 2019 at 17:26
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    $\begingroup$ @T.J.Crowder I imagine the technology would have been available (radar guided missile systems maturing through the '60s), but not the weight and power budget on the LRV for a radar system. $\endgroup$ Jan 1, 2019 at 17:53
  • $\begingroup$ Yeah, exactly. :-) $\endgroup$ Jan 1, 2019 at 17:57
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    $\begingroup$ Ah the 70s. When people could chew gum and pan cameras without looking at the capture screen. Lost skills. $\endgroup$ Jan 2, 2019 at 10:47
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    $\begingroup$ There's a parallel to that in movie-making even today. Look for focus-puller in the credits. Large film cameras are usually not single lens reflex, so the camera operator can't actually see the image that is going on the film. They have a viewfinder to frame the shot, but no idea of how focused the image is. This is the job of the focus-puller; he physically measures - with a tape-measure - the distance from lens to subject, then focuses the lens accordingly. He does this blind, without looking at the image. $\endgroup$ Jun 18, 2020 at 10:45

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