TABLE OF CONTENTS During the past 40 years, hundreds of spacecraft have been built in support of scientific, military, and commercial missions. Most can be broadly categorized as either three-axis-stabilized spacecraft, spin-stabilized spacecraft, or pallets; these types are distinguished by their configurations, internal equipment, and thermal-control designs. This chapter is a brief overview of the characteristics of each of these different types of spacecraft and the missions they support. Representative thermal designs for each type are discussed in more detail in Chapter 3.
The most common spacecraft configuration today is three-axis-stabilized. This type of spacecraft is characterized by a body that is roughly box-shaped and by deployable solar-array panels. Examples are the Defense Meteorological Satellite Program (DMSP), the Japanese Earth Resources Satellite (JERS), and the Russian communications satellite Gorizont, shown in Fig. 1.1. The bodies of these spacecraft are usually kept inertially stable except for a slow rotation induced about one axis to keep the payload antennas or sensors continuously pointed toward Earth as the satellite orbits. The solar-array panels are then counterrotated relative to the spacecraft body to keep them inertially fixed on the sun. Some three-axis spacecraft, such as the European Infrared Space Observatory (ISO, Fig. 1.1), have restrictions on attitude (the vehicle's orientation relative to an inertial coordinate system) or low power requirements that allow them to use fixed solar arrays that do not rotate to track the sun.
A typical internal equipment complement...
