ESA GNC Conference Papers Repository
Robust Skip Entry Guidance for accurate Leo or Lunar Returns
This paper presents a new hypersonic entry guidance scheme that has been designed by Astrium Space Transportation within the frame of the ESA-funded Robust Skip Entry program and that enables the safe and accurate return at any time from the Moon or from the International Space Station (ISS) of a capsule or a lifting body. The core technique of the guidance scheme is a predictor-corrector with a numerical prediction process (4th order Runge-Kutta method) that is compliant with the next generation of on-board processor and that enables to manage simultaneously the final downrange and crossrange constraints thanks to a guidance command law composed successive constant bank magnitude phases and roll-reversals. All phases transitions are commanded on energy criteria and, at each guidance call, the algorithm computes both the current phases bank angle magnitude and the next roll-reversal energy so it cancels the predicted downrange and crossrange errors. The performances of the guidance scheme have been assessed on 4 missions for both an ARD-like vehicle and an IXV-like vehicle: one ISS return mission with a direct reentry and 3 lunar missions requiring an intermediate skip-entry phase, for downranges from 7000 km to 10000 km. The presented performances have been evaluated on a Deimos Functional Engineering Simulator (FES). The performance evaluation has been divided in 3 steps: a first performance loop in a 3 Degrees Of Freedom (DOF) simulation environment (guidance only) with a navigation performance model representative of an hybrid IMU-GNSS navigation; a second performance loop in a 6 DOF simulation environment (guidance and control) with a navigation performance model representative of an hybrid IMU-GNSS navigation. For this purpose, two controllers have been developed by Astrium Space Transportation: one for each vehicle that is able to deal either with ISS or lunar returns; a last performance loop in a fully 6 DOF simulation environment (navigation, guidance and control) which is an on-going activity.