Base Observations of Artificial Earth Satellites

simultaneous observations of one and the same satellite from several points on earth that are separated by hundreds of kilometers.

Optical base observations are organized for low-orbiting satellites (maximum perigee, 400 km) in order to determine certain elements of their orbits (period of rotation, major semiaxis, and slope) for short intervals of time (one to two 24-hour periods). Analysis of the elements of the orbit obtained by this method permits investigation of temporary (nonperiodic) variations in the density of the earth’s atmosphere and their relationship to solar activity and the state of the earth’s magnetic field. Investigations carried out have made it possible to determine changes in atmospheric density caused by these factors at an altitude of 200–250 km with an amplitude of 20–90 percent in the course of one to two 24-hour periods. The times at which changes in density begin are defined with an accuracy of eight to ten hours.