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Science 46 years ago: First U.S. spacecraft, Ranger 4, impacts Moon
Science 46 years ago: First U.S. spacecraft, Ranger 4, impacts Moon | 46 years ago: First U.S. spacecraft, Ranger 4, impacts Moon |
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| by William Atkins | |
| Tuesday, 22 April 2008 | |
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Ranger 4 was launched by an Atlas-Agena B rocket at 3:49:53 p.m. Eastern Standard Time (EDT), 20:49:53 Coordinated Universal Time (UTC). The launch vehicle sent the spacecraft approximately 229,541 miles (369,400 kilometers) to the Moon. At 7:49:53 p.m. EST (12:49:53 UT) on April 26, 1962, while traveling at about 5,963 miles (5,957 kilometers) per hour, the spacecraft impacted the surface of the Moon. Ranger 4 was a part of the U.S. Ranger program, a series of unmanned robotic missions to the Moon. The objective of the program was to take detailed images of the Moon’s surface and to send them back to Earth real time—before the spacecraft was destroyed upon impact with the Moon. The missions were designed by NASA’s Jet Propulsion Laboratory, in Pasadena, California. In all, nine spacecraft were designed and built. Each spacecraft contained six cameras. The wide-angle A-camera and the narrow angle B-camera were part of the F-channel cameras. The last image of the F-channel cameras would be taken between 2.5 and 5.0 seconds before impact, while at an altitude of about five kilometers above the surface of the Moon. The other four cameras were part of the F-channel series. The P1 and P2 cameras were narrow angle and the P3 and P4 were wide angle cameras. The last P-channel image would be taken from 0.2 to 0.4 seconds before impact, at an altitude of about 600 meters. The six cameras each gave about one thousand times more detail that the best images taken from the Earth. The spacecraft also contained an imaging system (television camera), a gamma-ray spectrometer, a radar altimeter, and a single-axis seismometer. The onboard computer on the Ranger 4 spacecraft failed due to a power failure, which caused its navigational system to fail and to cause the solar panels to not deploy. As a result, the spacecraft could not perform any of its preplanned operations and was unable to send back any images of the Moon. It impacted the far side of the Moon. How did Ranger 4 and the other spacecraft in the Ranger program help NASA to land astronauts on the Moon. Please read on. |
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