<h2>AAS  96-155</h2><h2>SPHERE-OF-INFLUENCE TO PLANET-FIXED COORDINATES TARGETING</h2><h4>V. R. Bond, McDonnell Douglas Aerospace; M. Munk, NASA Johnson Space Center</h4><h2> Abstract </h2>This paper presents the development of an algorithm for targeting a spacecraft which is on a hyperbolic trajectory to the latitude and longitude of a point fixed to the surface of a rotating planet. The motivation for this development is the proposed "Mars In-Situ Resource Utilization Sample Return"(MISR) mission. The MISR concept is to land a propellant production plant and hardware for collecting samples on the Martian surface. In order to simplify design and to minimize cost for this conceptual mission the MISR spacecraft will use a direct atmospheric entry mode at Mars arrival and at Earth return.<br><br>