Why can I see through this astronaut on the Apollo 11 footage?

Question

I’m not sure if this is the correct place to put this but I’d assume it’s a photography thing.

In this video When Aldrin is climbing down the ladder of the lander I can see the horizon through him. Why is this?

I’d also like to add that this is not related to moon landing deniers just my own curiosity about how this happens.:)

Thanks guys

I’d also like to add that this is not related to moon landing deniers... So glad you included that detail... plus it pretty much eliminates the chance of you being the second person to be hit in the jaw by Aldrin. — End Anti-Semitic Hate, Jul 23 '21 at 02:01
ever-so-slightly related in Space SE: Why shadows of the blades on Ingenuity navcam photos looks brighter than shadows of the legs? — uhoh, Jul 23 '21 at 12:18

score 39 · Answer 1 · edited Jul 23 '21 at 22:26

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The exterior camera on the LEM was basically a miniaturized television camera, all based on state of the art late 60's video technology.

A television camera looking at the lunar surface in full daylight without even the benefit of an atmosphere to diffuse the harsh light will be extremely susceptible to all the foibles of the video camera tubes of the era.

I will attempt to explain my very layperson's understanding of how this ghostly afterimage of bright objects works, but the details of the electronics involved would be a better subject over on the Electrical Engineering board.

Based on what research I've been able to do, the early Vidicon tubes were particularly desirable for television because, though their signal output was low, their signal to noise ratio was also very high so they could be amplified and could therefore operate indoors very well. The downside being that anything that interfered with the signal at the source would also be amplified and show up on the output image.

One cause of this signal interference is heat buildup from bright lights hitting the imaging surface. This heat increases the electrical conductivity of that area of the imaging surface, essentially amplifying the output in that area slightly and causing an afterimage. Letting this go on for a long time can result in damage to the electrical properties and cause burn in on the image.

The camera spent between 17 and 18 minutes between the time Mr. Armstrong descended the ladder until after the famous descent photo was taken and Mr. Aldrin this video takes place. This is more than enough time staring at the lunar surface to build up enough heat for a strong afterimage. Once something blocked the excess light (like, for example, a giant space suit) the surface is able to cool and the afterimage slowly fades away.

edited Jul 23 '21 at 22:26

Community

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answered Jul 21 '21 at 03:41

LightBender

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Beat me to it! The technology of the time used vidicon tubes for imaging. They were very subject to burn-in and lag. – user10216038 Jul 21 '21 at 03:44
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Yeah, and they put a lot more thought into protecting all the film on the ship. – LightBender Jul 21 '21 at 03:49
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Here is an interesting youtube video by Writer/director S G Collins explaining from a photographic perspective why, ironically, we did not have the technology to fake the moon landing in 1969. https://www.youtube.com/watch?v=_loUDS4c3Cs – user10216038 Jul 21 '21 at 03:54
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@user10216038 clearly we just faked it later and then sent it back in time. – user253751 Jul 21 '21 at 10:55
I would expect the burned-in image to be the negative of the real image. (highly exposed areas would become less sensitive) On the picture the "burned-in" image looks to be positive. It also seems to disappear slowly. Why? --- I do not know much about video camera tubes. If it was a vidicon tube are not the very exposed parts of the image just glowing for a number of seconds? Also as I understand it vidicon is normally sensitive to infrared. I suppose the photoconductive target in vidicon can heat up in the highly exposed areas and produce a positive image for a long time. – pabouk - Ukraine stay strong Jul 21 '21 at 14:44
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I agree with you about everything but the timeline. The Modular equipment stowage assembly containing the camera was deployed by Armstrong after he stepped onto the LEM 'porch'. The first clear TV image was received about 40 seconds later. He reached the bottom of the ladder about a minute and a half after that. Timeline here – BobT Jul 21 '21 at 15:41
That's pretty cool information, I'd not seen a timeline that detailed before. Thanks for that, I'll update the answer accordingly. – LightBender Jul 21 '21 at 15:45
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It would be nice to include, specifically, which foible is responsible for the artifact in question. An external link is nice, but it's always preferable to have the meat of the answer actually in the answer. This doesn't really explain what's going on. – J... Jul 21 '21 at 16:43
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@pabouk: The image wasn't "burned in". If the stripes which are read out by a camera have any space between them, charges may slowly move between that space and the portions that are read out by the camera. Only a small portion of the charges that is in such regions will move the the scanned-out portion each frame, meaning that any ghosting from them will be much fainter than the main image, but will also fade much more slowly. – supercat Jul 21 '21 at 17:29
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This doesn't answer the question though. You normally don't see through actors on a television camera. – pipe Jul 23 '21 at 07:07
@pipe You're not seeing through anything in this image, either. You're seeing the residual heat caused by the camera having been pointed at the bright background for several minutes slowly dissipating from the surface of the television camera's tube. – Michael C Jan 19 '23 at 12:17

Mark Foskey · Answer 2 · 2021-07-22T19:28:43.417

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To get down to the mechanics of how these challenging conditions could enable you to "see through" the astronaut, I think what is happening is this. In a TV camera of that era, the light effectively created an image of electrical charge (or some change in electrical properties) in the imaging surface, and that change was read off by a scanning electron beam. Normally, the electrical changes revert back to zero between each scan, but with such high contrast that was not happening. So a leftover image of the lunar background was slowly fading from the camera tube as Buzz (I said Neil at first but was corrected) stepped down the ladder, creating a double-exposure effect.

edited Jul 22 '21 at 19:28

answered Jul 21 '21 at 18:43

Mark Foskey

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Bingo. Best answer yet. +1 – J... Jul 21 '21 at 20:26
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Actually, that's Buzz coming down the ladder. But the rest of the answer is correct. – dotancohen Jul 22 '21 at 07:44
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@dotancohen I'm trusting you on that. :-) – Mark Foskey Jul 22 '21 at 19:29
@MarkFoskey If we suppose that history is correct and Armstrong was the first, and further suppose that someone had to hold the camera to make this video, it's a very good guess that the person shown here is Aldrin. There is the interesting case of Armstrong's selfie but nobody agrees with me on that. :-) – uhoh Jul 24 '21 at 23:55
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Nobody had to hold the camera for Armstrong. It was mounted on the LM. – Mark Foskey Jul 25 '21 at 04:09

score 14 · Answer 3 · answered Jul 21 '21 at 15:39

The TV cameras of that era were of the vacuum tube type. Artifacts of various types degraded the images they generated. To name a few – ghosting, smearing, burn-in, comet tails, luma trails both negative and postitive and blooming. What you are seeing is a trail of a scan of a bright highlight that is generating a trail. All this was common to TV images of that period.

Why can I see through this astronaut on the Apollo 11 footage?

3 Answers3