At 0027 UT(universal time) on July 29, 1977 an interplanetary shock wave arrived at the front side magnetosphere and triggered substantial geomagnetic activity throughout the day. The propagation of the resulting MHD wave within the magnetosphere has been studied with measurements from a total of six satellites in (or near) the geostationary orbit and the interplanetary space and groundbased magnetometers. The signal transmission from the front side magnetopause down to the equatorial ionosphere corresponded to an average wave speed of v equals 600 km/sec. A propagation speed of v equals 90 km/sec was found for the signal transmission in the outer magnetosphere in and beyond the geostationary altitude. The results compared reasonably well with model calculations.The heated air rises, and the density at the orbit of satellites up to about 1,000 km (621 mi) increases significantly. This results in increased drag on satellites in space, causing them to slow and change orbit slightly. Unless Low Earth Orbit satellites are routinely boosted to higher orbits, they slowly fall, and eventually burn up in Earth's atmosphere.
Journal of Geophysical Research, vol. 87, Aug. 1, 1982, p. 5901-5910.
Research sponsored by the U.S.Department of Energy;
Bundesministerium fuer Forschung und Technologie
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