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Friday, November 29, 2013

First Pictures of the Far Side of the Moon (1959!)

On October 7, 1959, the Soviets sent an "automatic interplanetary station" to the moon.  This, in itself, was an amazing achievement.  Even more amazing is how they managed -- using 1950s technology -- to photograph the far side of the moon and get the images back to the earth. 

The Soviet document on the Harvard site (below) says that the transmitter put out "a few watts" and used semiconductors.  There appears, however, to have been at least one vacuum tube aboard (the cathode ray tube used to scan the chemically developed photo negatives).  Frequency modulated analog video similar to FAX) was used to send the data.


From Wikipedia:

Luna-3 was the first successful three-axis stabilized spacecraft. During most of the mission, the spacecraft was spin stabilized, but for photography of the Moon, the spacecraft oriented one axis toward the Sun and then a photocell was used to detect the Moon and orient the cameras towards it. Detection of the Moon signaled the camera cover to open and the photography sequence to start automatically. The images alternated between both cameras during the sequence. After photography was complete, the film was moved to an on-board processor where it was developed, fixed, and dried. Commands from the Earth were then given to move the film into a scanner where a spot produced by a cathode ray tube was projected through the film onto a photoelectric multiplier. The spot was scanned across the film and the photomultiplier converted the intensity of the light passing through the film into an electric signal which was transmitted to the Earth (via frequency-modulated analog video, similar to a facsimile). A frame could be scanned with a resolution of 1000 (horizontal) lines and the transmission could be done at a slow-scan television rate at large distances from the Earth and a faster rate at closer ranges.
The camera took 29 pictures over 40 minutes on 7 October 1959, from 03:30 UT to 04:10 UT at distances ranging from 63,500 km to 66,700 km above the surface, covering 70% of the lunar far side. Seventeen (some say twelve) of these frames were successfully transmitted back to the Earth, and six were published (frames numbered 26, 28, 29, 31, 32, and 35). They were mankind's first views of the far hemisphere of the Moon.

More info: http://www.svengrahn.pp.se/trackind/luna3/Luna3story.html#Film

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1 comment:

  1. Nice article about the far side of the moon !
    Maybe you can get more on space from this website : http://www.svengrahn.pp.se/

    73´s from PA3DMI - Amsterdam


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