AAS 96-170

OPTIMAL DESCENT TRAJECTORIES FOR SCIENTIFIC PAYLOADS USING ICBM-CONVERTED LAUNCHERS

P. Teofilatto and F. Santoni, Universita degli Studi di Roma "La Sapienza"

Abstract

In recent years many strategic missiles (InterContinental Ballistic Missiles, ICBM) withdrawn from military use have been converted for civil applications, e.g. suborbital and orbital flights for scientific programs. One of these, the Zodiac scientific mission concerns the experimental investigations of tropical cyclones. The mission consists of several steps. First a circular orbit 150 Km high is reached by an ICBM converted launcher. Then a module has to be delivered to a descent trajectory. The module deploys a cluster of automatic descending capsules endowed with parachutes. The experimental measurements begin when the cluster reaches an appropiate height and velocity, which are the initial conditions of the experiment. In this paper the minimum time descent trajectories are evaluated as function of the transfer angle between the initial circular orbit and the target. However most of these trajectories violate the maximum load and heat transfer constraints. The most suitable trajectories matching both the minimum time and the load/heat requirements are shown for any transfer angle.