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Moon TV

July 24th, 2009

nasaHow many times have you growled as your mobile drops-out, and uttered those often repeated words, “How come 40 years ago, they can get TV from the moon and today they can’t even get a phone to work over a few kilometres?”  Well as this seems to be moon week, I thought I’d find out.

In 1969, when Apollo 11 landed on the moon, the Americans were desperate to prove their technological prowess to the Russians and to the world.  They’d shown they could fly there and back but walking on the moon, and proving you’ve done it, was to be the next giant leap.  For TV, this was to be a giant leap into an abyss, and those charged with getting the proof of America’s triumph back to earth, were shifting nervously in their lab seats.  Three major companies competed for the prowess of being the one who shot the moon walk, Westinghouse, RCA and GE, and Westinghouse  got the job.  The question was, should they go for black and white, or push themselves for the next big thing, colour.

The spec for the camera to be used on the moon’s surface demanded a device that could be used in a vacuum and at temperatures from 250 degrees Fahrenheit down to minus 300 degrees.  It had to be light, use little power and be able to withstand the usual shocks, radiation and meteor showers expected on the moon.  It had to be able to cope with the contrast of a scene lit by direct sunlight with black shadows, and it had to be of point-and-shoot design for the inexperienced camera operator, Neil Armstrong. They decided to play safe and stick with black and white. It was simple, more robust and well understood technology, but even this took them five years and over a million dollars to make.  A colour camera was developed for the friendlier environment of the Command Module but it was black and white for the most important outside broadcast of the century.

Apollo 11 TV CameraThe camera weighed seven pounds, measured 11x3x6 inches, came with four fixed focal length lenses – wide,  two standard, one for day, one for night, and telephoto – changeable with gloved hands, and was built of highly reflective aluminium. It had its own manual of course. It had to run off the batteries on the Lunar Module so would have limited transmitter power, now the other problem was how to get the pictures 250,000 miles back to earth.

While they could feasibly send a standard 525 NTSC signal back from the Command Module with its extra power and large antenna, neither would be available for the moon cam. So, they came up with a whole new TV format. The camera was designed to shoot at 10 frames a second rather than the usual 30 and with a reduced the number of lines to 320, which made the picture of lesser quality, but  meant less information to transmit.  The Lunar Module had only a one meter antenna, it was planned that the crew would unfold an umbrella-like, larger antenna on the surface, but later decided it would be too time consuming and they wanted those pictures asap after touchdown.  So the receiver on earth would have to be a huge antenna to pick-up the tiny signal.

small_1960s_telescopeThis was assigned to three radio telescopes one at Goldstone in California and Honeysuckle Creek, and Parkes in Australia,  the subject of Oz movie The Dish.  Each station tracked the moon and received the signals to be re-transmitted via satellite back to Houston. But there was a problem.  The non-standard TV signal from the camera had to be converted for use by the world’s TV’s. The solution was surprisingly simple.  The receiving stations would have the 10 frame per second pictures on their monitors, so they simply pointed a standard TV camera at the monitor then relayed the pictures from that camera onwards.

Now Parkes was standing-by to bring great prowess for Australia’s contribution to this moment in history.  The mission schedule meant they would receive and re-transmit pictures of the first walk on the moon. parkes radio telescopeBut Neil Armstrong decided to change the schedule and rather than resting before the moon walk, wanted to go straight for it.  This would mean the moon wouldn’t have risen over the horizon in view of the Parkes dish.  But the design of the suits meant it took Armstrong so long to get into it that by the time he was ready, the moon had risen and Parkes could see it.  NASA’s plan was to use the three telescopes and switch between whichever had the best pictures, as it turned out, Parkes’ better pictures were used for the whole mission, stamping their footprint on Apollo history.

Today, colour pictures from the International Space Station and Shuttle are commonplace, they can even mount cameras on various parts of the shuttle to give everyone a ride with it into space. No vibration or contrast problems now.  And Google Earth now bring you Google moon, with 360 degree views of the surface and those first footprints. As for mobile phone signals,  NASA hasn’t solved that one yet, though they did give us Black and Decker drills, I guess a satellite dish is the only answer!


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