Apollo video transmissions

[turbonium]

The color video camera of Apollo 11 was only used in the CM, because, if I've read correctly, the LM antenna only could transmit "lower bandwidth" signals of the B & W video camera.

So I have some questions:

1. Why didn't they simply record color footage on the Moon for viewing after returning to Earth, like they did in taking color photographs?

2. There was an small S band antenna in the Apollo 11 LM. What was the bandwidth transmission capability of this antenna?

I should add here that this issue is not meant to be evidence of a hoax, although the thread subject seems to be appropriate enough to include in this forum category.

[LunarOrbit]

They did have a colour film camera that was mounted in the window of the LM. There is some footage of Armstrong and Aldrin setting up the American flag, which was in the field of view of the film camera.

The purpose of the black & white video camera was to allow people on Earth to witness the first steps on the moon live as they happened... it wasn't perfect but I can't imagine not having the live broadcast. It wouldn't have been the same listening to the EVA on the radio (not that it matters to me... I was born in 1975 so it was never a "live broadcast" for me ).

[turbonium]

I can understand getting a live video feed to Earth, by the best means possible (in this case in B & W). I didn't know the color video camera was aboard the LM - then why didn't they detach it and carry it around on the surface?

Btw, you missed every Apollo mission? I saw Apollo 11 in my Grade 2 classroom! (I'm an old coot!)

[LunarOrbit]

I'm not sure why they didn't bring the film camera outside, but I'm sure someone here knows the answer.

Yeah... I was born two months after the Apollo-Soyuz docking, which was after Skylab. In fact there were no Americans in space at all for the first five and a half years of my life (until the first Space Shuttle launch in 1981).

[Obviousman]

The camera in the LM was a 16mm camera that took 'snapshots' at prescribed intervals.

During the landing, it ran as a normal 16mm movie camera. During surface activities, it ran at one frame per second (IIRC) in order to maintain a record of activity (within it's field of view)) but not force the astronauts to have to go back and reload it all the time.

[Kiwi]

turbonium said:

I saw Apollo 11 in my Grade 2 classroom! (I'm an old coot!)

I saw Sputnik 1 overhead when I was 8 and listened to the Apollo 11 landing live on the radio when I was 20. (I'm an even older coot!)

You've seen Jay's description of the Apollo 11 TV transmission at Clavius? It's a must-read.
www.clavius.org/tvqual.html

I didn't know the color video camera was aboard the LM - then why didn't they detach it and carry it around on the surface?

It wasn't a video camera, it was a 16mm film camera, and it was taken outside on later missions. There is a little film of the rover in motion from Apollos 15 and 16, including the Grand Prix, but during Apollo 15 most of the film magazines didn't work outside, though I've never heard why.

IIRC the spacecraft's colour video camera was only used in the command module, although it was taken into the lunar module temporarily when they were connected and the hatch was open. The transmissions of it doing that in Eagle can be viewed on the Spacecraft Films' DVDs. From memory, when they first open the hatch and the light in the LM comes on, Mike Collins says, "See, just like a refrigerator." I posted the full version in the "Apollo Astronauts - Joking Around" thread at BAUT:
www.bautforum.com/showthread.php?t=18178

The lunar surface video camera was stored in the MESA.

The purpose of the black & white video camera was to allow people on Earth to witness the first steps on the moon live as they happened...

One disturbing thing about this is that a few recent documentaries don't show the first step. Neil's legs couldn't be seen any lower than about mid-thigh, but it is obvious that he stepped sideways and perhaps a little lower from the footpad. Many documentaries now have him saying "I'm going to step off the LM now..." and show his second jump down to the footpad from the last rung of the ladder, which he executed earlier.

Typical "Hollywood." More important to show more action than to show the actual event.


<Fixed typo>

[Joe Durnavich]

2. There was an small S band antenna in the Apollo 11 LM. What was the bandwidth transmission capability of this antenna?

The LM and its small S-band antenna could transmit a color signal. In fact, it did just that on the next mission, Apollo 12 (and on 14 and 15 for a bit). Apollo 11 didn't have a color camera mostly for the reason that one wasn't available that would work outside in the vacuum of space. For Apollo 12, they took the color camera that Apollo 10 used in the CM cabin and modified it to work outside the spacecraft.

Engineers and technicians were scrambling in 1969 to get the color capability in place. They missed the deadline for Apollo 11.

The notion that the antenna limited the bandwidth to just a black-and-white signal comes from our very own JayUtah's Clavius page linked to in a post above. Jay's page may be correct in a sense of engineering decisions made earlier in the program. From my readings, I gather that early on, they didn't expect that the small LM antenna transmitting to an 85-foot antenna on Earth would have enough signal-to-noise ratio to handle a color signal. Signal-to-noise determines the information bandwidth, that is, how much information you can successfully pass through a given communications pipe.

When 1969 rolled around, however, they found themselves with these humongous 210-foot beasts of antennas. The extra dish area on the ground compensated for the smaller dish size on the spacecraft. (Which, in fact, is one of the reasons for building larger antennas on the ground: you can then put smaller and lighter antennas, transmitting equipment, and power sources on the spacecraft.)

The other notion of bandwidth, radio frequency bandwidth, was an issue too, but it had nothing to do with the LM antenna. This issue is more complicated technically, but in short, the engineers on the ground were able to develop increasingly clever workarounds to it as Apollo progressed.

[turbonium]

The LM and its small S-band antenna could transmit a color signal. In fact, it did just that on the next mission, Apollo 12 (and on 14 and 15 for a bit). Apollo 11 didn't have a color camera mostly for the reason that one wasn't available that would work outside in the vacuum of space. For Apollo 12, they took the color camera that Apollo 10 used in the CM cabin and modified it to work outside the spacecraft.

A couple of follow up questions, if you don't mind...

What modifications were needed to operate the camera in space?

Why didn't they use the Apollo 11 CM color camera and modify it instead of the Apollo 10 CM camera?

The notion that the antenna limited the bandwidth to just a black-and-white signal comes from our very own JayUtah's Clavius page linked to in a post above. Jay's page may be correct in a sense of engineering decisions made earlier in the program.

Yes, that's where I read about the bandwidth issue. As a side note, IIRC, the usable bandwidth was 4KHz for B&W TV transmissions, and remained at 4 KHz when color TV's were introduced, so they would be compatible with the majority of people who still had only B&W TV sets.

I gather that early on, they didn't expect that the small LM antenna transmitting to an 85-foot antenna on Earth would have enough signal-to-noise ratio to handle a color signal.

So you are saying that Jay should revise his answer on Clavius? To wit, that the antenna did have the bandwidth capability to transmit color signals, but NASA engineers didn't think that it did?

[dwight]

Hi Turbonium,

I'm sitting in Vienna after a loooong flight from Sydney, so apologies if I am a bit vague. The Apollo 11 BW video camera was completely flight and surface checked for the lunar EVA. Stan Lebar from Westinghouse had conducted several tests for a jerry-rigged BW camera to be modified without the need for increased bandwidth. Unfortunately as mentioned above, the timing was not in his favour and so the BW was flown. This had the added security of having been fully tested and spaceflight rated. Dont forget that in 1969 colour was still a novelty for many countries, Australia didnt convert until 1974. So it was not as major a problem then as we see it today.

Jay's site may not mention this as this is information I have recently gotten hold of. I, like you, am very frustrated with the lack of colour on the first LEVA, but dems da breaks. To actually record onto a decent format within the LM was prohobited by the cumbersome recording devices of the time.

[turbonium]

Hi dwight. Thanks for the info, and no worries, it's not vague.

Cheers

[PhantomWolf]

I have a feeling that 12's colour camera was the CSM from 11, though it might have flown on 10 as well.

[JayUtah]

Some of the CM television cameras were reused, but I don't remember for which missions.

[Joe Durnavich]

As a side note, IIRC, the usable bandwidth was 4KHz for B&W TV transmissions and remained at 4 KHz when color TV's were introduced, so they would be compatible with the majority of people who still had only B&W TV sets.

Yes, that was case for American television formats(although, 4 MHz instead of 4 KHz). An analog television signal here in the US consists of a video signal plus an audio signal 4.5 MHz above it. To remain compatible with existing television sets, engineers had to design a color scheme that would fit within the lower 4.2 MHz.

Apollo's bandwidth issues arose for similar reasons. Apollo spacecraft transmitted a Unified S-Band signal (USB). USB combined television, voice, telemetry, and ranging in one signal. Back in, oh, 1962 or so, engineers allocated the lower 500 KHz (or 0.5 MHz) for the video signal. That is just enough for a low resolution black-and-white signal transmitted at 10 frames per second.

Above that in the USB frequency spectrum, at 1.024 MHz and 1.25 MHz were the telemetry and voice signals. The color cameras generated a signal that took up about, oh, maybe 2 MHz of bandwidth. The cameras transmitted 30 frames per second and were a bit higher resolution than the black-and-white cameras. They were able to transmit that through the LM and receive it on the ground, but the voice and telemetry signals were mixed in with the video. The result was interference in the form of a herringbone pattern across the image--exactly what we see in the Apollo 12 television.

As a crude workaround, they simply filtered out the received signal above 1 MHz to eliminate as much of the interfering voice and telemetry signals. Such filtering still resulted in usable television, but at the expense of a loss of picture detail. The Apollo 14 image quality was quite soft because of this. For later missions, they developed equipment to cleanly "subtract out" the voice and telemetry signals, leaving behind a mostly intact 2 MHz color signal.

So you are saying that Jay should revise his answer on Clavius? To wit, that the antenna did have the bandwidth capability to transmit color signals, but NASA engineers didn't think that it did?

As you can see, I am not adept at explaining technical matters without getting unnecessarily technical. Jay should revise the page, but I don't know the best way to revise it and keep it short and simple. Apollo technical progress was quite rapid and occurring on many fronts. I lack the capability to cut through it all to the heart of the matter.

[JayUtah]

Clavius does need to be revised. It's misleading to say that the antenna was too small; that doesn't tell the whole story. I'll do my best to make it concise, but I won't allow it to be blatantly incorrect.

[Joe Durnavich]

You should also check with Wood, Dinn, et al for whatever they know about why color wasn't used on Apollo 11.