Effect of moon's shadow on geostationary satellite power systems

A geostationary satellite enters the moon's shadow, at unevenly spaced intervals, on the average of twice a year. Such events occur when the moon moves between the sun and the satellite. The present investigation has the objective to provide some understanding of such eclipses. The geometrical relations involved are examined, and data regarding the eclipses for a geostationary satellite at 270 deg E and 90 deg W for the time from 1980 to 1999 are presented. Most of the eclipses are found to be partial, and last less than an hour. The effect of an eclipse on a solar array is to reduce power. Some satellites, such as those for TV broadcast, are not designed to continue operations during an eclipse. However, reduced operations should be possible with a smaller number of channels.