Information, Communication, and Space Technology

4 Satellites

4.1 Introduction

A satellite is any smaller object traveling around a larger object.¹ By this definition, the Moon is a satellite to the Earth, and the Earth is a satellite to the Sun. For the purpose of our discussion here, a satellite is meant to be a human-made spacecraft placed in space to orbit another body. Some spacecraft are crewed, such as the space shuttle, and most are uncrewed, such as NASA’s Hubble Space Telescope. If the satellite has an onboard radio transmitter or other energy signals, they are considered as active satellites, and if they do not and only reflect signals that are beamed at them from Earth, they ...