Luna 3
The dramatic first pictures of the unseen far side of the moon were sent to earth by the
Soviet Union spacecraft, Luna 3, in October 1959.
Luna 3 was the third spacecraft sent successfully to the
moon and was a vivid early triumph in the nascent human exploration of outer space. Though it returned rather poor pictures by later standards, the historic, never-before-seen views caused excitement and interest when they were published around the world, and a tentative atlas of the far side of the moon was created after image processing improved the pictures.
These views showed mountainous terrain, very different from the near side, and only two dark, low-lying regions which were named Mare Moscovrae and Mare Desiderii .
Encyclopedia
The dramatic first pictures of the unseen far side of the moon were sent to earth by the
Soviet Union spacecraft,
Luna 3, in October 1959.
Luna 3 was the third spacecraft sent successfully to the
moon and was a vivid early triumph in the nascent human exploration of outer space. Though it returned rather poor pictures by later standards, the historic, never-before-seen views caused excitement and interest when they were published around the world, and a tentative atlas of the far side of the moon was created after image processing improved the pictures.
These views showed mountainous terrain, very different from the near side, and only two dark, low-lying regions which were named Mare Moscovrae and Mare Desiderii . Mare Desiderii was later found to be composed of a smaller mare, Mare Ingenii , and other dark craters.
Spacecraft design
The spacecraft was a cylindric canister with hemispheric ends and a wide flange near the top. The probe was 130 cm long and 120 cm at its maximum diameter at the flange. Most of the cylindric section was roughly 95 cm in diameter. The canister was hermetically sealed and pressurized at 0.23 atmosphere .
Solar cells were mounted on the outside of the cylinder and provided power to the chemical batteries stored inside the spacecraft.
Jalousies for thermal control were positioned along the cylinder and opened to expose a radiating surface when the internal temperature exceeded 25 degrees Celsius. The upper hemisphere of the probe held the covered opening for the cameras. Four antennae protruded from the top of the probe and two from the bottom. Other scientific equipment was mounted on the outside, including
micrometeoroid and
cosmic ray detectors, and the
Yenisey-2 imaging system. Gas jets for attitude control were mounted at the lower end of the spacecraft.
Photoelectric cells helped maintain orientation with respect to the
sun and
moon.
The spacecraft had no rockets for course adjustment. The interior held the cameras and film processing system, radio equipment, propulsion systems, batteries, gyroscopic units for attitude control, and circulating fans for temperature control. The spacecraft was spin stabilized and was directly radio-controlled from the Soviet Union.
Mission
After launch on an 8K72 rocket over the
north pole the Blok-E escape stage was shut down by radio control from earth at the proper velocity to put Luna 3 on a course to the moon. Initial radio contact showed the signal from the probe was only about half as strong as expected and the internal temperature was rising. The spacecraft spin axis was reoriented and some equipment shut down resulting in a temperature drop from 40 °C to about 30 °C. At a distance of 60,000 to 70,000 km from the moon, the orientation system was turned on and spacecraft rotation was stopped. The lower end of the station was pointed at the sun, which was shining on the far side of the moon.
The spacecraft passed within 6,200 km of the moon near the south pole at its closest approach at 14:16 UT on October 6 1959 and continued on to the far side. On October 7 the photocell on the upper end of the spacecraft detected the sunlit far side of the moon and the photography sequence started. The first picture was taken at 03:30 UT at a distance of 63,500 km from the moon, and the last picture 40 minutes later from 66,700 km.
A total of 29 pictures were taken, covering 70% of the far side. After the photography was complete the spacecraft resumed spinning, passed over the north pole of the moon and returned towards earth. Attempts to transmit the pictures to the Soviet Union began on October 8 but were believed to be unsuccessful due to the low signal strength. As Luna 3 drew closer to earth a total of 17 viewable but poor quality photographs were transmitted by October 18. Contact with the probe was lost on October 22. The probe was believed to have burned up in earth's atmosphere in March or April of 1960, but may have survived in orbit until after 1962.
Lunar Photography
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. 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 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 and 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, and 6 were published humanity's first views of the far hemisphere of the moon.
The imaging system was developed by P.F. Bratslavets and I.A. Rosselevich at the Leningrad Scientific Research Institute of Television and the returned images were processed and analyzed by Iu.N. Lipskii and his team at the Sternberg Astronomical Institute.
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