Earth-Based Observations of Artificial Earth Satellites

simultaneous observations of the same satellite from several points on the earth that are hundreds of kilometers apart.

Optical base observations are organized for low-altitude satellites (perigee of up to 400 km) for the purpose of determining certain elements of the satellite’s orbit (the period of revolution, the semimajor axis, and the inclination of orbit) at small intervals of time (1–2 days). The analysis of orbital elements obtained in this manner makes possible the investigation of short-term (nonperiodic) variations in the density of the earth’s atmosphere and their dependence on solar activity and the earth’s magnetic field. Investigations have shown that these factors may cause deviations of 20–90 percent in the atmospheric pressure (at an altitude of 200–250 km) over a period of 1–2 days. The starting times of these density variations have been determined with an accuracy of 8–10 hrs.