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Ranger(rayn -jer) An American space program, originally intended to hard-land instruments on the lunar surface but upgraded in 1963 into purely photographic missions. The first five Ranger craft were launched between August 1961 and October 1962. Ranger 6, launched Jan. 30 1964, reached its target but suffered camera malfunction. The last three – Rangers 7, 8, and 9 – were launched on July 28 1964, Feb. 17 1965, and Mar. 21 1965. They obtained the first close-ups of the Moon, revealing the existence of boulders and meter-sized craters in the regolith: over 4300, 7100, and 5800 photographs were transmitted by Rangers 7, 8, and 9 respectively, leading to a great advance in our knowledge of the Moon. See also Luna probes; Lunar Orbiter probes; Surveyor; zond probes.
the name of a series of American spacecraft for lunar exploration (with the exception of Rangers 1 and 2, which were put into geocentric orbits and were designed to test onboard systems) and of the program for developing and launching these spacecraft (1959–65). The spacecraft were launched by Atlas-Agena Blaunch vehicles, with the exception of Ranger 8, which was launched by an Atlas-Agena D.
Rangers 3, 4, and 5 were similar in design and had six television cameras. The flight objectives were to obtain television pictures of the lunar surface, to conduct radar scanning of the moon and study the characteristics of lunar rocks using a gamma-ray spectrometer, and to accomplish a semisoft landing with an instrument package containing a seismometer. No soft landing on the moon was envisioned. After the unsuccessful flights of Rangers 3, 4, and 5, succeeding craft were modified, and two sets of three television cameras each were installed in place of the lunar capsule. The television equipment on Ranger 6 malfunctioned, and no pictures were made. During the lunar approaches of Rangers 7, 8, and 9, more than 17,000 photographs of the lunar surface were taken in the regions of Mare Cognitum, Mare Tranquillitatis, and the crater Alphonsus.
The maximum diameter of all Ranger spacecraft was 1.52 m, the height was 2.52 m with antenna and solar panels stowed and 3.12 m with the equipment extended, and the maximum cross-sectional dimension was 5.18 m; the weight was between 306 and 367 kg. The power supply system included solar cells and silver-zinc batteries, and the vernier engine installation operated on monopropellant fuel.
G. A. NAZAROV