TABLE OF CONTENTS Space vehicle design requirements do not, except in very basic terms, have an existence that is independent of the mission to be performed. In fact, it is almost trivial to note that the type of mission to be flown and the performance requirements that are imposed define the spacecraft design that results. Just as a wide variety of aircraft exist to satisfy different broad classes of tasks, so may most space missions be categorized as belonging to one or another general type of flight. Missions to near Earth orbit, for example, will impose fundamentally different design requirements than planetary exploration missions, no matter what the end goal in each case. In this chapter we examine a variety of different mission classes, with a view to the high-level considerations that are thus imposed on the vehicle design process.
Low Earth orbit (LEO) can be loosely defined as any orbit that is below perhaps 1000 km, or generally below the inner Van Allen radiation belt. By far the majority of space missions flown to date have been to LEO, and it is probable that this trend will continue. Examples of LEO missions include flight tests, Earth observations for scientific, military, meteorological, and other utilitarian purposes, and observations of local or deep space phenomena. Future missions can be expected to have similar goals plus the addition of new classes for purely commercial purposes. Indeed, the first generation of such commercial missions began appearing at the turn of...
