SATELLITE TRACK COMPUTATION FOR DISPLAY PURPOSES

A proposal to design and construct a display of satellite orbital information and related data introduced a need for a simple method of computing satellite position relative to the earth. A study of satellite orbital computation at NRL led to the development of a scheme with sufficient accuracy to make a useful display possible. The computation begins with the orbital elements. Next the satellite is located in polar coordinates on the orbital plane. These coordinates are then transformed to the earth latitude and longitude of the subsatellite point (defined here as the point on the earth's surface directly between the satellite and the center of the earth) and the height (distance) of the satellite above that point. The perturbing effects, rotation of perigee and precession of the nodes, are included in the computation. The results are expressed as geocentric earth longitude and latitude of the subsatellite point and the height above the earth's surface. Numerical examples show satellites can be located by such computational methods, with errors that are easily less than 0.5 degrees in longitude and of about 1 percent in height. (Author)