Orbiting Geophysical Observatory


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Orbiting Geophysical Observatory

(OGO), series of six orbiting observatories (see observatory, orbitingobservatory, orbiting,
research satellite designed to study solar radiation, electromagnetic radiation from distant stars, the earth's atmosphere, or the like. Because the atmosphere and other aspects of the earth's environment interfere with astronomical observations from the
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) launched between 1964 and 1969 by the National Aeronautics and Space Administration (NASA) to study the earth's atmosphere, ionosphereionosphere
, series of concentric ionized layers forming part of the upper atmosphere of the earth from around 30 to 50 mi (50 to 80 km) to 250 to 370 mi (400 to 600 km) where it merges with the magnetosphere, the region of the Van Allen radiation belts.
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, and magnetosphere and the solar windsolar wind,
stream of ionized hydrogen—protons and electrons—with an 8% component of helium ions and trace amounts of heavier ions that radiates outward from the sun at high speeds.
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. In order to provide global coverage, three of the satellites (OGO-2, OGO-4, and OGO-6) were launched into low polar orbits while the other three (OGO-1, OGO-3, and OGO-5) were placed in eccentric orbits ranging out as far as almost 92,830 mi (150,000 km). Each observatory carried 20–25 instruments, including cosmic ray detectors, counters, and telescopes, ionization chambers, Geiger counters, magnetometers, spectrometers, photometers, micrometeoroid detectors, and ion and electron traps. Among the significant achievements of the OGO program were the first observations of daytime auroras and of the protons responsible for the ring of electric current that surrounds the earth during magnetic storms, the collection of data showing the interaction of the solar wind with the earth's magnetosphere, and the verification of the existence of the plasmapause, the inner boundary of the region of trapped radiation in the magnetosphere.

Orbiting Geophysical Observatory

(OGO) Any of a series of US geophysical satellites, first launched in Sept. 1964, for studying the Earth's atmosphere, ionosphere, magnetic field, radiation belts, etc., and how these are influenced by the solar wind and other phenomena. Moving mainly in highly elliptical orbits, the satellites could carry out many studies simultaneously for prolonged periods.