SATELLITE COORDINATES AND REAL-TIME POSITION COMPUTATION
Abstract
The size and shape of a satellite orbit and its orientation with respect to the earth are defined by these six modified orbital elements: (Semimajor axis of the elipse), (eccentricity of the ellipse), (inclination of the orbital plane to the earth's equatorial plane), (argument of perigee), (longitude of the ascending node), and (reference time). Equations are given for the computation of the geocentric spherical coordinates of satellite positions. These equations were programmed for computation by the Naval Research Laboratory Electronic Digital Computer (Narec) and positions for the satellite 1958 Beta 2 (Vanguard I) were computed. The resulting positions, using the modified orbital elements, were compared with positions computed by the IBM Space Computing Center for the same satellite and the same time interval. The maximum differences for each coordinate computed were: longitude, 0.071 degrees, latitude, 0.197 degrees, and height, 3.85 statute miles. Several timing runs were performed where no printout of positions was obtained, but answers were, instead, stored in the Narec memory. From these runs, the speed which position coordinates are computed by the Nare was estimated to be 5.40 position solutions per second for the minimum usable tolerance of the computer, and 7.69 position solutions per second for the largest tolerance value compatible with three decimal accuracy in the answers. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 12, 1961
- Accession Number
- AD0264949
Entities
People
- W.d. Dahl
Organizations
- United States Naval Research Laboratory