the name of a series of American artificial satellites of the moon; the program of the development and launching of these satellites (1964-67). A total of three ground test models and five flying models were manufactured. Of the latter, the first three had the principal task of locating zones on the moon suitable for the landing of the Surveyor spacecraft and of the lunar modules of the Apollo spacecraft. Eight such zones were found. The other two Lunar Orbiters photographed potential landing sites, the regions of the near side of the moon that are most interesting from a scientific standpoint, and the regions of the far side (the polar regions) that had not been photographed by previous Lunar Orbiters. After completing the principal task of surveying the moon, the spacecraft were used to study the meteoric and radiation conditions in the vicinity of the moon and the lunar gravitational field, as well as to align ground stations of the ground control and instrumentation complex and test on-board equipment.
The Orbiters were launched by Atlas-Agena D launch vehicles in the period from Aug. 10, 1966, to Aug. 1, 1967. The Lunar Orbiter weighed 386 kg, measured 1.68 m high (with folded antennas and panels holding solar batteries), and had a maximum width of 1.52 m. The photographic unit, which weighed 68 kg, consisted of two cameras with a resolution of 1 m and 8 m from an altitude of 46 km.
G. A. NAZAROV