Ranger program

Ranger 6789.svg
Block III Ranger spacecraft
ManufacturerJet Propulsion Laboratory
Country of originUnited States
BusBlock I, Block II, Block III
First launchAugust 23, 1961
Last launchMarch 21, 1965
Related spacecraft
1964 71395L-Ranger.svg
Block II Ranger spacecraft
First image of the Moon returned by a Ranger mission (Ranger 7 in 1964)

The Ranger program was a series of unmanned space missions by the United States in the 1960s whose objective was to obtain the first close-up images of the surface of the Moon. The Ranger spacecraft were designed to take images of the lunar surface, transmitting those images to Earth until the spacecraft were destroyed upon impact. A series of mishaps, however, led to the failure of the first six flights. At one point, the program was called "shoot and hope".[1] Congress launched an investigation into "problems of management" at NASA Headquarters and Jet Propulsion Laboratory.[2] After two reorganizations of the agencies,[citation needed] Ranger 7 successfully returned images in July 1964, followed by two more successful missions.

Ranger was originally designed, beginning in 1959, in three distinct phases, called "blocks". Each block had different mission objectives and progressively more advanced system design. The JPL mission designers planned multiple launches in each block, to maximize the engineering experience and scientific value of the mission and to assure at least one successful flight. Total research, development, launch, and support costs for the Ranger series of spacecraft (Rangers 1 through 9) was approximately $170 million (equivalent to $1.05 billion in 2018).[3]

Ranger spacecraft

Program Ranger Organization Chart

Each of the block III Ranger spacecraft had six cameras on board. The cameras were fundamentally the same with differences in exposure times, fields of view, lenses, and scan rates. The camera system was divided into two channels, P (partial) and F (full). Each channel was self-contained with separate power supplies, timers, and transmitters. The F-channel had two cameras: the wide-angle A-camera and the narrow angle B-camera. The P-channel had four cameras: P1 and P2 (narrow angle) and P3 and P4 (wide angle). The final F-channel image was taken between 2.5 and 5 seconds before impact (altitude about 5 km) and the last P-channel image 0.2 to 0.4 seconds before impact (altitude about 600 m). The images provided better resolution than was available from Earth-based views by a factor of 1000. The design and construction of the cameras was led by Leonard R Malling.[4] [5] [6] [7] The Ranger program manager for the first six spacecraft was James D. Burke.[8]

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