Apollo TV camera
These cameras varied in design, with image quality improving significantly with each successive model.
Originally, these slow-scan television (SSTV) cameras, running at 10 frames per second (fps), produced only black-and-white pictures and first flew on the Apollo 7 mission in October 1968.
The cameras all used image pickup tubes that were initially fragile, as one was irreparably damaged during the live broadcast of the Apollo 12 mission's first moonwalk.
All of these cameras required signal processing back on Earth to make the frame rate and color encoding compatible with analog broadcast television standards.
Positioning the camera in the MESA made it possible to telecast the astronauts' first steps as they climbed down the LM's ladder at the start of a mission's first moonwalk/EVA.
[5] Since the camera's scan rate was much lower than the approximately 30 fps for NTSC video,[Note 2] the television standard used in North America at the time, a real-time scan conversion was needed to be able to show its images on a regular TV set.
[6] When the Apollo TV camera transmitted its images, the ground stations received its raw unconverted SSTV signal and split it into two branches.
The combined original and copied fields created the first full 525-line interlaced frame and the signal was then sent to Houston.
Image degradation was unavoidable with this system as the monitor and camera's optical limitations significantly lowered the original SSTV signal's contrast, brightness and resolution.
The video seen on home television sets was further degraded by the very long and noisy analog transmission path.
Then the network pool feed was sent by microwave relay to New York, where it was broadcast live to the United States and the world.
The camera had to be designed to survive extreme temperature differences on the lunar surface, ranging from 121 °C (250 °F) in daylight to −157 °C (−251 °F) in the shade.
[23] It was next used on Apollo 11, carried in the LM's descent stage, in the quad 4 Modularized Equipment Stowage Assembly (MESA).
They used three imaging tubes to generate red, green and blue (RGB) video signals which were combined to produce a composite color picture.
About 42 minutes into telecasting the first EVA, astronaut Alan Bean inadvertently pointed the camera at the Sun while preparing to mount it on the tripod.
The Sun's extreme brightness burned out the video pickup tube, rendering the camera useless.
When the camera was returned to Earth, it was shipped to Westinghouse, and they were able to get an image on the section of the tube that wasn't damaged.
[38] Procedures were re-written in order to prevent such damage in the future, including the addition of a lens cap to protect the tube when the camera was repositioned off the MESA.
Image quality issues appeared due to the camera's automatic gain control (AGC) having problems getting the proper exposure when the astronauts were in high contrast light situations, and caused the white spacesuits to be overexposed or "bloom".
The improved image quality was obvious to the public with the RCA camera's better tonal detail in the midrange, and the lack of the blooming that was apparent in the previous missions.
Once the LRV was fully deployed, the camera was mounted there and controlled by commands from the ground to tilt, pan, and zoom in and out.
