In 2008 I wrote a piece for Archive Zones magazine about the television pictures sent back from the moon and the search for the missing instrumentation tapes containing the original pictures sent back by Apollo 11. The tapes have still not been found, although some early-generation broadcast videotape has recently been revealed and is, at time of writing, up for auction. Below is the article I wrote in 2008 ...
Polaroid photo taken of the live slow-scan pictures from Apollo, showing a clearer image than the surviving video.
I’m sure I am not alone in vividly remembering being awake in the early hours of July 21st 1969. Neil Armstrong was about to step out onto the surface of the moon. Our whole family—not to mention 600 million others around the world—watched those grainy, jumpy, ghostly monochrome images of a shadowy figure in a space suit moving cautiously off the lunar module (LM) ladder and onto the surface. One small step for man, being imaged by a specially designed Westinghouse camera, transmitted a quarter of a million miles to ground stations in Australia and then beamed around the world by satellite and cable.
It never occurred to me to question exactly what I had been looking at, and have seen countless times since. It was the moon landing video and if you wanted a copy you sent a tape to NASA public affairs and they’d send you a copy.
Only that is not the whole story; because the real tapes of the moon landing video are missing and what we have been watching for nigh on forty years is the result of optical standards conversion, which was basically pointing a television camera at a television screen.
The television feed from the lunar module was a slow-scan TV signal. It was monochrome, linear gamma, progressive scan, 320 lines at 10 frames per second with a 4:3 aspect ratio and horizontal resolution up to 200 lines. Bandwidth in the downlink to Earth was scarce and the power in the LM was limited as it ran on batteries and only had a one-metre dish antenna. The specified bandwidth of the video signal was flat within 3 dB to 500 kHz. The system had to operate when the high-gain antennae at Goldstone and Honeysuckle Creek were unavailable since the original timing of Armstrong and Aldrin’s Extra Vehicular Activity (EVA) would have put these big dishes on the wrong side of the planet. The television signal was sharing bandwidth with voice and continuous telemetry and this was an analogue link.
The waiting world would definitely want to see the first man on the moon taking his first steps. The conundrum was that, as any director knows, you should shoot this from outside the LM. NASA knew that Westinghouse had produced a camera tube which could both operate in low light and avoid the smearing that such activity usually produced with conventional camera tubes such as vidicons or image orthicons. This was known as the SEC camera and, having been coaxed out from behind some of its military secrecy, such devices had already been deployed on Apollo 9.
The camera was stowed in the LM’s MESA (Modularised Equipment Stowage Assembly) on a special shock mount. A hole was cut in the MESA’s insulating blanket to allow the lens to see out. When the MESA was opened by Armstrong after he came out of the LM, but before he stepped off, the camera would be positioned almost exactly upside down and pointing at him.
And so it was. Armstrong stepped off the LM, the waiting millions saw and heard him utter those immortal words, and he and Buzz Aldrin walked out onto the lunar surface, during which the camera was moved out onto a tripod with a view of the LM and its surroundings, including the US flag they planted.
Those slow-scan TV signals were picked up in California at Goldstone and Australia at both the Honeysuckle Creek earth station and the Parkes radio telescope. Apart from engineers at the tracking stations and at the Sydney communications centre (where the Parkes pictures were converted), everyone on the planet saw the converted pictures, not the slow-scan originals. If you add the further degradation introduced by 80 thousand kilometres of analogue satellite links you can start to appreciate why those original slow-scan images were better quality.
The anticipated signal-to-noise of the video was around 35 dB. The trip from the moon will have added noise as well as other artefacts but we know that those original images were much better than the ones currently preserved for posterity. We know this because Polaroid stills were taken off the slow-scan monitors (basically CRTs with slow-decay phosphors) and even these show significantly more detail and texture than the NTSC conversion.
Were the slow scan signals recorded? Yes they were. They were recorded as part of the mission telemetry on 14-inch reels of 1-inch 14 track analogue instrumentation tape running at 120 inches-per-second. There were two machines running to cover overlaps at each of the prime receiving sites. The tapes were copied and the originals were sent to the Goddard Space Flight Centre. The plan was that the originals would then be wiped and reused. What happened to any of those tapes is currently a mystery.
A large number of data tapes were transferred from Goddard to the US National Archives during the 1970s but a careful search of both documentation and storage shelves failed to locate the moon landing tapes from Apollo 11. According to documentation in the NA, Goddard had requested that the tapes (along hundreds of others) be returned to them for permanent retention in 1975 but there is no record of them at Goddard.
The television feed was not the only moving picture record of the moon landing EVA. Also on board the LEM was a 16mm Maurer film camera with a 18mm lens, which could run at 1, 6, 12 and 24 frames a second using 130 foot magazines. This camera recorded the familiar shot out of the LM window as the Eagle lands, in which the dust kicked up by the rocket motor, and the shadow of the spacecraft as it descends, are clearly visible. Much less familiar are the images captured by this camera during Armstrong's EVA. This colour film material was long kept by NASA, along with other film shot by the astronauts in space and on the moon, in ultra-cold storage under liquid nitrogen, and was therefore very difficult to access. Recently, however, NASA transferred all this material to 1080p high-definition video, a stunningly rich visual archive which the producers of the recent cinema documentary (and FOCAL awards nominee) "In the Shadow of the Moon" show for the first time. As Archive Producer Chris Riley and director Davis Sington explained to Archive Zones, it proves a revelation.
The roughly two-minute long shot itself is a mute "top shot" out of the LM window looking directly down the ladder as Armstrong descends. The highly dramatic pause before Neil steps off the LM, and the first tentative step itself, as the astronaut sways gently to test the firmness of the lunar surface, are clearly visible. Synchronised for the documentary with the voice loop between Armstrong and Mission Control, this sequence proves unexpectedly powerful, in many ways the emotional climax of the movie. Whether or not an original slow-scan video tape is ever located, these film images are likely to remain the best visual record of this seminal moment in the history of mankind.
In 2002, a data tape was uncovered at Honeysuckle Creek in Australia which was believed to be a souvenir dub of Armstrong’s first steps. In 2004 this tape was given some gentle conservation treatment by Screensound Australia and hand-carried to Goddard where it could be played on compatible equipment that was still available. Unfortunately it turned out to be from an earlier simulation, but the successful playback did at least suggest that if the Apollo 11 tapes could be found, they could be replayed.
It is possible that there were unofficial antennas tracking and recording the mission; the moon was above the horizon for both the USSR and China that night. However, there is no evidence to suggest that anyone else recorded the slow-scan video. NASA also allowed Australia to distribute PAL conversions of the pictures to their domestic audience and because of the pivotal role played by Australia in the moon landing communications, that is the most likely place to find something outside the NASA facilities, particularly Goddard.
There is an enthusiastic team searching for the tapes, led by Richard Nafzger from NASA Goddard and Stan Lebar, who managed the project to build that camera at Westinghouse. This interest is partly because of the obvious wish to preserve such a significant point in human history, but also because the data from those moon landings are now of interest to those people planning new missions to the moon and beyond.
None of this diminishes the impact of what we have already. In some ways, a high quality feed of the moon walk might even have seemed less amazing. Certainly the poor quality of the video has helped to fuel the conspiracy theorists who claim that the moon landing never happened. But, as a firm believer in preserving as high a quality as you can, I am watching this search with great interest.
(With thanks to Stan Lebar, David Sington and Chris Riley)
There was colour television in the Command Module, orbiting overhead. This was a field-sequential system, which used a three-colour wheel that rotated synchronously in front of camera and monitor changing colour each field. Prior to adopting NTSC, the FCC in America had briefly adopted a field-sequential system proposed by CBS as the US standard for colour television and it was considered impractical for an NTSC camera to be used. It would have been too big and unreliable in the harsh conditions. Field-sequential colour was also impervious to the kinds of colour-phase problems that NTSC (and to a much lesser degree PAL) have always suffered.
Documents open in new windows
The Search for the original Apollo 11 Moonwalk TV tapes (Honeysuckle Creek)
Apollo Television (Nasa)
Mission Photography (Universities Space Research Association)
… and for the video engineers amongst you …