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A near-earth optical communications terminal with a corevolving planetary sun shieldThe umbra of a planet may serve as a sun shield for a space-based optical communications terminal or for a space-based astronomical observatory. An orbit that keeps the terminal or observatory within the umbra is desirable. There is a corevolution point behind every planet. A small body stabilized at the planet corevolution point will revolve about the sun at the same angular velocity as the planet, always keeping the planet between itself and the sun. This corevolution point is within the umbra of Mars but beyond the end of the umbra for Mercury, Venus, and earth. The Mars corevolution point is an ideal location for an astronomical observatory. There, Mars obstruct less than 0.00024 percent of the sky at any time, and it shades the observatory completely from the sun. At the earth corevolution point, between 51 and 84 percent of the solar disk area is blocked, as is up to 92 percent of the sunlight. This provides a reduction from 3 dB to 11 dB in sunlight that could interfere with optical communications if scattered directly into the detectors. The variations is caused by revolution of the earth about the earth-moon barycenter.
Document ID
19900028826
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Kerr, E. L.
Date Acquired
August 14, 2013
Publication Date
November 1, 1989
Publication Information
Publication: British Interplanetary Society, Journal
Volume: 42
ISSN: 0007-084X
Subject Category
Astronautics (General)
Accession Number
90A15881
Distribution Limits
Public
Copyright
Other

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