• atmospheric re-entry
• entry guidance
• spaceliner
• trajectory simulation

In the scope of this Master Thesis, a primary model of SpaceLiner trajectories for the reference mission Australia – Europe has been performed in the Space Launcher System Analysis department, at the German Aerospace Center (DLR). The SpaceLiner 7-3 50 passenger concept has been selected as the reference vehicle for the mission, which consists in three phases namely Ascent phase, Descent Phase and Booster Fly back Phase. Trajectory simulation with existing tools has been made according to structural, thermal and feasibility considerations. The reference mission has been defined and trajectories are plotted for back and forth in Section 3.
Alternative off nominal conditions of SpaceLiner mission have been analyzed in Section 4 and trajectory trade-offs have been considered under those possible reductions of performance margin. In the presented study three different cases are taken into account: Reduction in performance of engine (Case 1), Reduction in ascent propellant estimation (Case 2) and finally the failure of one booster engine (Case 3).
A simple and innovative control guidance law has been proposed in Section 5 to compute the active controls that govern the descent phase, which allowed the reduction of the heat load acting on the vehicle. The showed guidance provides the steering commands for trajectory control from the final condition of the ascent until the TAEM conditions. This design is based on a semi analytic solution of the equations of motion defining the drag acceleration profile referred to specific energy that meets the landing position of the re-entry flight while maintaining the flight within system and operational constraints. Guidance commands are based on a control law that ensures bank angle modulation while the angle-of-attack remains constant.