Luna 11

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This subset of the second generation Luna spacecraft, the Ye-6LF, was designed to take the first photographs of the surface of the Moon from lunar orbit.

A secondary objective was to obtain data on gravitational anomalies on the Moon (later identified by U.S. researchers as mascons) also detected by Luna 10.

Using the basic Ye-6 bus, a suite of scientific instruments included an imaging system similar to the one used on Zond 3, which was capable of high- and low-resolution imaging and whose lenses faced the direction of the S5.5 main engine. This package replaced the small lander capsule used on the soft-landing flights. The resolution of the photos was reportedly 49 to 66 feet (15 to 20 meters).

A technological experiment included testing the efficiency of gear transmission in vacuum for the future Ye-8 lunar rover (which worked successfully for 5 hours in vacuum). Luna 11, launched only two weeks after the U.S. Lunar Orbiter, successfully entered lunar orbit at 21:49 UT on Aug. 27, 1966 about 5 minutes earlier than planned. Parameters were 102 x 742 miles (163.5 × 1,193.6 kilometers).

Within 3 hours of lunar orbit insertion, the spacecraft was to be stabilized for its imaging mission, which would include taking 42 frames over a 64-minute session. Due to an off-nominal position of the vehicle, the camera only took images (64 of them) of blank space. Investigators determined that a foreign object had probably been dislodged in the nozzle of one of the attitude control thrusters.

The other instruments functioned without fault (although no data was returned by the spectrophotometer) before the mission formally ended on Oct. 1, 1966 after power supply had been depleted.

- Credit: NASA