Lunar Photography

Description

The purpose of this experiment was to obtain photographs of the lunar surface as the spacecraft flew by the moon. The imaging system was designated Yenisey-2 and consisted of a dual lens camera, an automatic film processing unit, and a scanner. The lenses on the camera were a 200 mm focal length, f/5.6 aperture objective and a 500 mm, f/9.5 objective. The camera carried 40 frames of temperature- and radiation resistant 35-mm isochrome film. The 200 mm objective could image the full disk of the Moon and the 500 mm could take an image of a region on the surface. The camera was fixed in the spacecraft and pointing was achieved by rotating the craft itself. A photocell was used to detect the Moon and orient the upper end of the spacecraft and cameras towards it. Detection of the Moon signalled the camera cover to open and the photography sequence to start automatically. After photography was complete, the film was moved to an on-board processor where it was developed, fixed, and dried. Commands from Earth were then given and the film was moved to a scanner where a bright spot produced by a cathode ray tube was projected through the film onto a photelectric 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 Earth. A frame could be scanned with a resolution of 1000 lines, the transmission could be done at a slow rate for large distances from Earth and a faster rate at closer range.

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 of these frames were successfully transmitted back to Earth, humanity's first views of the far hemisphere of the Moon.