Live from the Moon: Lunar TV Camera
Q: What kind of video camera was recording/broadcasting the Apollo moon mission on July 20, 1969? What were some of the challenges in making a video camera specifically for the moon trip?
A: This is the camera that set the eyes of the world upon the first images of humankind’s walk on the moon during Apollo 11.
At the start of the space program, TV didn’t go along. Typical cameras weighed about 400 pounds and were designed only for studio use. But NASA began to become aware of the tremendous scientific and popular need for moving pictures.
The challenge: Send back live pictures of the first steps on the moon, and do it with the only piece of mission equipment that would have to work in all phases of the trip. In other words, the portable video camera was important, but not essential. There was no need to bring two.
Design needs: The camera should weigh as little as possible, use very little power, be self cooling and survive in temperatures ranging from 250 degrees Fahrenheit in the lunar day, and minus 300 degrees in the lunar night. In addition, it would need to withstand launch shocks, and possibly meteor showers and particle radiation. It had to be easy for encumbered astronauts to hold.
Oh yes, it also had to take pictures — even when the only light around was earthshine.
The Solution: It took five years, hundreds of people, and over a million dollars to develop the seven-pound SEC vidicon camera. But it was ready on July 20, 1969, a pioneering example of solid state and integrated circuit technology. All Neil Armstrong had to do was point and shoot. The signal was beamed to a receiving dish in Australia, converted to standard commercial broadcast format and shown to more than 500 million people.
CHALLENGE: Reduce the size and weight of the TV camera from a 400-pound, bathtub-sized studio model.
SOLUTION: Microminiaturize circuits to create a 7-pound camera, 11 x 3 x 6 inches.
CHALLENGE: Must work during extreme temperatures — lunar night falls to 300 degrees below zero, and lunar day rises to 250 degrees Fahrenheit.
SOLUTION: Lightweight aluminum base metal, with a highly reflective silverplate finish. On top of the camera, a thermal semi-hard white paint coating to reflect heat during the day. Two metal shields prevent heat loss during the lunar night.
CHALLENGE: Must withstand eight times the force of gravity on liftoff.
SOLUTION: Brackets with built-in vibration and shock isolation provided.
CHALLENGE: Handle a wide range of ambient light, many angles, and variety of depths of field.
SOLUTION: Design a lens with a neutral-density filter to deal with the high-intensity light of the lunar day, and provide a lunar night lens with a large aperture to admit all available light.
CHALLENGE: Suited and gloved astronauts need ease of use; manual focusing and aperture changes should be eliminated.
SOLUTION: Provide four fixed-focal-length lenses that are mounted by slot as needed.http://blip.tv/file/get/Thedvshow-Apollo11LunarCamera664.flv
Power Supply In/Video Signal Out
CHALLENGE: Keep power to a minimum of 28 volts, with a maximum power drain no greater than 6 watts from any module.
SOLUTION: Use integrated, molecular circuits wherever possible.
CHALLENGE: Keep cable lines to a minimum.
SOLUTION: Enclose Teflon-coated power wires and video coaxial cables in a glass braid. Bring into the camera through the tubular handle at its base.
CHALLENGE: Cable connections can’t withstand the pressures of a space environment.
SOLUTION: Design a new kind of cable connector — with an easy push insertion — that can hold up in a hostile space environment and also withstand the pulling and bending of portable use.
CHALLENGE: Provide an optimum means for astronauts to hold and operate the portable camera, and test optimum size, shape and mounting position of the handle.
SOLUTION: Astronaut preference and relative simplicity determined the single tubular unit on the bottom of the camera.
CHALLENGE: Provide high-resolution pictures in a narrow bandwidth that can both capture motion and be precise enough for scientific study. Share bandwidth with voice, biomedical and other telemetry data.
SOLUTION: Provide, with the flip of a switch, the choice of 10 frames per second/320 lines per frame scanning ratio to capture motion; or .625 frames per second/1280 lines per frame for scientific still pictures. Provide scanning conversion back on earth for the commercial viewing standard of 30 frames per second/525 lines per frame.
CHALLENGE: Reduce the 1,200 components of a typical studio camera to 250. Adapt synchronizer, deflection unit, power supply, automatic light and gain controls, and video modules to meet the space-flight hardware requirements of minimum size and weight.
SOLUTION: Pioneer the use of molecular, integrated circuits.
CHALLENGE: Provide a simple, low-power camera sensor that works in the dim lunar night and the bright lunar day.
SOLUTION: Patented Secondary Electron Conduction tube, with unique target feature that eliminates the “smear problems” associated with low-light sensor systems, with automatic gain and light controls that are useful during the day.