Orbits and Related Issues

This chapter presents aspects of orbit geometry that are fundamental to comprehension of the design and modes of operation of artificial satellites. It examines various aspects of the satellite's motion around the Earth for its communication with the Earth; these include Keplerian orbits, orbit parameters, perturbations, eclipses, and the geometric relationships between satellites and Earth stations. The chapter discusses the conditions for occurrence and duration of the conjunction with the sun for particular types of orbit. It describes elliptical orbits with non-zero inclination, geosynchronous elliptic orbits with zero inclination and non-zero inclination, sun-synchronous circular orbits with zero inclination, and geostationary satellite orbits. The chapter shows that, under the effect of various perturbations, the orbital parameters change with time. Perturbations of the orbit are the result of various forces that are exerted on the satellite other than the force of attraction of the central, spherical, and homogeneous body.