Guidance for an aerocapture maneuver

Aerocapture, which has been described as "essential for cost-effective space transportation," imposes severe guidance and control problems. A closed-loop control law is formulated that provides stable control in the presence of reasonable errors in approach guidance and in knowledge of the atmospheric density profile. Navigational accuracy requirements can be satisfied by a combination of approach tracking and onboard inertial measurements, supplemented, in the case of a Mars encounter, by a radar altimeter or its functional equivalent.