![]() Both transmitters operated in the S band at about 2295 MHz. Communications were via a 10 W transmitter and the directional one meter diameter high-gain antenna for transmission of photographs, and a 0.5 W transmitter and omnidirectional low-gain antenna for other communications. Navigational knowledge was provided by five sun sensors, the Canopus star sensor, and the inertial navigation system. Three axis stabilization and attitude control were provided by four 4 newtons (1 lbf) nitrogen gas jets. Propulsion for major maneuvers was provided by the gimballed velocity control engine, a hypergolic 440 newtons (100 lbf) thrust Marquardt Corp. The batteries were used during the brief periods of occultation when no solar power was available. Power of 375 W was provided by the four solar arrays containing 10,856 n/p solar cells which would directly run the spacecraft and also charge the 12 A ![]() Mounted on the perimeter of the top deck were four attitude control thrusters. The nozzle of the engine protruded through the center of the shield. ![]() The third deck consisted of a heat shield to protect the spacecraft from the firing of the velocity control engine. Above the equipment deck, the middle deck held the velocity control engine, propellant, oxidizer, and pressurization tanks, Sun sensors, and micrometeoroid detectors. Also extending out from the base of the spacecraft were a high gain antenna on a 1.32 m (4 ft 4 in) boom and a low-gain antenna on a 2.08 m (6 ft 10 in) boom. Four solar panels were mounted to extend out from this deck with a total span across of 3.72 m (12.2 ft). The equipment deck at the base of the craft held the battery, transponder, flight programmer, inertial reference unit (IRU), Canopus star tracker, command decoder, multiplex encoder, traveling-wave tube amplifier (TWTA), and the photographic system. The spacecraft was composed of three decks supported by trusses and an arch. The main bus of the Lunar Orbiter had the general shape of a truncated cone, 1.65 m (5 ft 5 in) tall and 1.5 m (4 ft 11 in) in diameter at the base. The Boeing-Eastman Kodak proposal was announced by NASA on 20 December 1963. A second photo of the whole Earth was taken by Lunar Orbiter 5 on 10 November 1967. The first full picture of the whole Earth was taken by Lunar Orbiter 5 on 8 August 1967. The film was then processed, scanned, and the images transmitted back to Earth.ĭuring the Lunar Orbiter missions, the first pictures of Earth as a whole were taken, beginning with Earth-rise over the lunar surface by Lunar Orbiter 1 in August, 1966. The film was moved during exposure to compensate for the spacecraft velocity, which was estimated by an electro-optical sensor. The axes of the two cameras were coincident so the area imaged in the HR frames were centered within the MR frame areas. Both lenses, a 610 mm (24 in) narrow angle high resolution (HR) lens and an 80 mm (3.1 in) wide angle medium resolution (MR) lens, placed their frame exposures on a single roll of 70 mm film. The Lunar Orbiters had an ingenious imaging system, which consisted of a dual-lens camera, a film processing unit, a readout scanner, and a film handling apparatus. All of the Lunar Orbiter spacecraft were launched by Atlas-Agena-D launch vehicles. Lunar Orbiter 4 photographed the entire nearside and nine percent of the far side, and Lunar Orbiter 5 completed the far side coverage and acquired medium (20 m or 66 ft) and high (2 m or 6 ft 7 in) resolution images of 36 preselected areas. The fourth and fifth missions were devoted to broader scientific objectives and were flown in high-altitude polar orbits. These were flown at low-inclination orbits. The first three missions were dedicated to imaging 20 potential crewed lunar landing sites, selected based on Earth-based observations. Intended to help select Apollo landing sites by mapping the Moon's surface, they provided the first photographs from lunar orbit and photographed both the Moon and Earth.Īll five missions were successful, and 99 percent of the lunar surface was mapped from photographs taken with a resolution of 60 meters (200 ft) or better. The Lunar Orbiter program was a series of five uncrewed lunar orbiter missions launched by the United States from 1966 through 1967.
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