Reply to Comment on the Termperature Distribution in a Spinning Sphere During Atmospheric Entry

ther, the directions of these components have a degree of invariance in tha t one component remains normal to the radius vector and the other component remains normal to the line of apsides. Where this property has been noted in the literature its derivation has been accomplished by geometry in which little use is made of terms that are physically familiar in orbit mechanics. Also, no inferences seem to have been made that there is any practical application which takes advantage of the invariance of these two velocity components. To illustrate these invariant velocity components, designated Vk and Vp (Fig. 1), assume a two-body conic trajectory, either elliptic or hyperbolic, where