Guidance and Control Strategy for the CALLISTO Flight Experiment

In order to make access to space more affordable for both scientific and commercial activities the German Aerospace Center (DLR), the Japan Aerospace Exploration Agency (JAXA) and the French National Centre for Space Studies (CNES) joined in a trilateral agreement to develop and demonstrate key technologies for a future reusable launch vehicle. In the joint project CALLISTO (Cooperative Action Leading to Launcher Innovation in Stage Toss back Operations) a reusable vertical take-off, vertical landing rocket is developed as a demonstrator for a reusable first stage. The test flight operations will take place at the Guiana Space Centre (GSC), in French Guiana. This paper gives a textual overview of the control strategies of the DLR/JAXA guidance and control subsystem for the CALLISTO test flights. The main assumptions adopted for design and simulation will be illustrated, and an overview of the foreseen mission profiles will be given. The missions consist of multiple flight phases having different aerodynamic configurations of the vehicle: the ascent phase, the boost-back maneuvers, the aerodynamic phase, and the powered descent and landing phase. We describe the sequence of events and the high-level G&C mode for each phase, including the criteria for the phase transitions as evaluated by the on-board computer. To autonomously control the vehicle during the different flight phases multiple classic and modern control methods are utilized. Finally some simulation results based on a preliminary G&C design are being discussed