Autonomous on-orbit targeting and guidance for a reusable launch vehicle

Kistler Aerospace is currently developing a two stage reusable launch vehicle to place payloads in circular low Earth orbit. This vehicle is unique in that both stages return to the vicinity of the launch site and land on parachutes and airbags. Draper Laboratory has developed the Guidance and Targeting algorithms for the on-orbit phase of the Kistler mission. This phase consists of five burns, for each of which Targeting supplies desired terminal conditions. Guidance must then meet these conditions by directing the thrust vector during the burn. Targeting is driven by two primary requirements. First, the vehicle maneuver capability on entry is limited, so Targeting accuracy is essential for landing in a small zone near the launch site. Second, unlike almost all previous programs, the Kistler vehicle will not communicate with the ground while on orbit, so Targeting must be completely autonomous. Guidance draws heavily on algorithm designs from the Space Shuttle, but a new Guidance mode developed specifically for the Kistler mission to provide an accurate orbital period for phasing is described.