TABLE OF CONTENTS In this section we will treat briefly the problem of reentry of a ballistic missile into the Earth's atmosphere. A complete analysis of reentry involves heat/energy transfer and/or dissipation, atmospheric models, aerodynamics, etc. Such analysis is beyond the scope of this work and will not be discussed here. Furthermore, no consideration will be given here for reentry of manned orbiting vehicles or spacecraft, since in reentry of manned spacecraft there are severe decelerations for human occupants, intense aerodynamic heating, and the tactical aspect of having control of landing location. For this reason, we will not treat manned flight reentry. Specifically, reentry is characterized by he dissipation of great quantities of kinetic and potential energy by the missile (or spacecraft). While a large fraction of this energy is transferred to the atmosphere, relatively large quantities of it will be deposited in the craft as heat. It is well known that when a ballistic missile reenters the atmosphere after having traveled a long distance, its speed will be very high and the remaining time to ground impact will be relatively short. The small displacement distance traveled by ballistic missiles after they reenter the atmosphere can be accurately modeled, to a first-order approximation, using a simplified flat-Earth constant-gravity approximation. Reentry has become a generic term for a broad function that may be accomplished by a variety of vehicle configurations in a variety of environments.
The parameters that affect the reentry problem, and are unique to ballistic missiles, are the following
