Author Topic: Apollo 15 waving flag  (Read 9301 times)

Offline HeadLikeARock

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Apollo 15 waving flag
« on: August 10, 2013, 04:13:04 AM »
Hi folks

For a few years there's been a theory that during an Apollo 15 EVA, there is evidence that an astronaut caused a flag to move before he walked past it, proving it was filmed in an atmosphere, therefore faked.

- 2:36 onwards

I must admit I too thought the flag did indeed move before he touched it, but analysis of the flags movement after he moves away clearly shows it was in a vacuum. I assumed something else must have caused the flag movement, such as static electricity: an argument I wasn't completely convinced by, but it can't have been air pressure as the subsequent motion of the flag learly pointed to a vacuum. I neglected to consider the possibility that the flag didn't actually move, but only appeared to move due to some kind of video artefact or bloom as the astronaut comes into view. I've re-visited this one recently, and think I can finally lay it to rest.

There are a couple of white dots that I think are lens flares on the flag. Close inspection reveals that these white dots also move at exactly the same time as the flag does, in the same direction. Wind cannot possibly be responsible for this. It must be some kind of video artefact.

Here's a link to a couple of screenshots:-

http://s142.photobucket.com/user/headlikearock/media/Apollo%2015/flag-wave-new-1a_zps2ee975bf.jpg.html
http://s142.photobucket.com/user/headlikearock/media/Apollo%2015/flag-wave-new-2a_zps33e4b7ac.jpg.html

I made an animated GIF using these 2 crops:-

http://s142.photobucket.com/user/headlikearock/media/Apollo%2015/flag-wave-new-1_zpsfa1b51cc.jpg.html
http://s142.photobucket.com/user/headlikearock/media/Apollo%2015/flag-wave-new-2_zpsf45e22ce.jpg.html

Which you can see here:-



If the forum software doesn't display the GIF properly, click the link:-

http://i142.photobucket.com/albums/r81/headlikearock/Apollo%2015/flag-wave-new-gif_zps435e5ced.gif

I think that seals the deal!

Offline ka9q

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Re: Apollo 15 waving flag
« Reply #1 on: August 10, 2013, 05:43:15 AM »
Yes. Among the possible artifacts is 'blooming', a common phenomenon in cathode ray tubes (and therefore increasingly unfamiliar nowadays).

CRTs include not only the display devices that have since been replaced by LCD and plasma panels but also TV cameras before they were universally replaced with solid state CCD and CMOS imagers. In both kinds of CRTs, an electron beam is caused to scan a target with either electrostatic or electromagnetic deflection. Anything that affects that scanning process will cause the image to shift even when the actual scene hasn't changed at all. One of the most common mechanisms is a change in the high voltage used to accelerate the electron beam, an artifact called "blooming". And the most common reason for the beam accelerating voltage to change is a change in average current load caused by a change in average picture brightness -- as can happen when someone walks into the field of view.

This could have happened in the lunar camera itself or in the CRT used to make the permanent film record in the Apollo archives.

 

Offline beedarko

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Re: Apollo 15 waving flag
« Reply #2 on: August 12, 2013, 02:42:41 AM »
I neglected to consider the possibility that the flag didn't actually move, but only appeared to move due to some kind of video artefact or bloom as the astronaut comes into view. I've re-visited this one recently, and think I can finally lay it to rest.

The flag most definitely is moving. A simple frame-by-frame comparison of the bottom corner with adjacent landscape features proves that much. The exact cause is, to my knowledge, still the subject of debate, but this is not an example of blooming.

As for the video artifacts or "lens flare" dots you mention, they appear to be fixed at a stationary  point within the frame.  I'm not seeing any sort of associated movement with the flag like you describe.

I think that seals the deal!

Sorry, I don't think it does.  It's clearly not air movement, but the real cause has never been demonstrated to my satisfaction.


Offline ka9q

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Re: Apollo 15 waving flag
« Reply #3 on: August 12, 2013, 04:06:03 AM »
At what time?

There's no question that the flag is moving after the astronaut passes. A 3D model of the scene shows that his left arm was close enough to the flag (which was rotated toward the camera) to brush past it. The only question is whether this is the only thing that happens, or if there's also some initial apparent movement due to video artifacts.

Don't forget the unusual color system in use. Until it was phased out with the transition to digital, the United States NTSC scheme transmitted linear combinations of all three primary colors simultaneously over three separate channels. The luminance or Y channel occupied the video baseband and the I and Q color channels were carried on a quadrature-modulated subcarrier, with the Y channel being backwards compatible with a monochrome ("black and white") receiver.

Until digital imaging, generating NTSC required three CRT imaging tubes, one for each primary color, and a prism and color filter scheme to separate the light from the subject. This would have required a much larger, heavier and more power-hungry camera for Apollo, so a sequential color system was used instead. A single imaging tube with a rotating color wheel (blue, green and red in that order) carried the primary color images sequentially over a single channel. This signal was converted to NTSC on the ground and relayed to the networks. Because the primary colors are not sampled at the same time, various artifacts were produced on moving subjects. We could easily be seeing some of them here, particularly on the astronaut as he moves into the scene.

Offline Mag40

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Re: Apollo 15 waving flag
« Reply #4 on: August 12, 2013, 05:12:09 AM »
I neglected to consider the possibility that the flag didn't actually move, but only appeared to move due to some kind of video artefact or bloom as the astronaut comes into view. I've re-visited this one recently, and think I can finally lay it to rest.

The flag most definitely is moving. A simple frame-by-frame comparison of the bottom corner with adjacent landscape features proves that much. The exact cause is, to my knowledge, still the subject of debate, but this is not an example of blooming.

Before or after he runs past it? There is a small part of the horizon next to the edge of the flag....if you run a gif with just the edge of the flag and that part of the horizon.....the horizon definitely moves to the right with the flag and the two lens flares. The lower lens flare does a weird wobble when you play it slow....so there is something weird going on with this scene. JMO.