October 28, 2015
Together 151 gelatin silver prints, each 10 x 10 inches. Partial suite of high resolution shots of images IV-5 through IV-195. Numerous photos marked NASA LRC for NASA Langley Research Center. Several photos hand labelled as "REPANELED."
An incredible assemblage, showing partial views of nearly every crater on the near side of the moon, including Kepler, Goddard, Joliot-Curie, Ptolemaeus, and Mercator to name but a few. The Lunar Orbiter program was a series of five unmanned lunar orbiter missions launched by the United States from 1966 through 1967 for the purposes of selecting a landing site for the Apollo missions. "The prime objective ... was to photograph the entire front side of the Moon at a resolution considerably better than is possible from Earth" (James S. Martin, Deputy Lunar Orbiter Project Manager; see Cortright p 109).
Lunar Orbiter IV was intended to perform a wide-reaching and systematic photographic survey of lunar surface features in order to increase the scientific knowledge of their nature, origin, and processes, and to serve as a basis for selecting sites for more detailed scientific study by later orbital and landing missions.
Initial photography by Lunar Orbiter IV began on May 11, 1967, at an orbit of 2,706 by 6,111 km with an inclination of 85.5 degrees and a period of 12 hours. Problems began almost immediately when the camera's thermal door began to respond poorly to commands to open and close, leading to fears the door could become stuck in the closed position, blocking the camera. The door was left open and extra attitude control maneuvers were made to correct for light leakage into the camera. Nevertheless, On May 13 it was discovered that light leakage was damaging some of the film and the door was tested and partially closed, only for some lens fogging to occur as a side effect of the attitudinal changes. Finally, problems with the readout drive mechanism starting and stopping from May 20 resulted in a decision to terminate the photographic portion of the mission on May 26. Nevertheless, the entire film was read and transmitted for a total of 419 high-resolution and 127 medium-resolution frames covering 99% of the Moon's near side at resolutions from 58 to 134 meters. Its mission complete, Lunar Orbiter IV was used for tracking until it crashed into the lunar surface through natural decay of its orbit by October 31.
This highly important collection comprises a significant proportion of Lunar Orbiter IV's high resolution images and was an essential part of the preparations for the first manned Moon landings two years later.