ESA GNC Conference Papers Repository

Future launchers may be equipped with an autonomous safety function, implemented on-board, activating self-destruction in case of major contingency during the launch. Such a fully autonomous safety would simplify the required ground infrastructure used nowadays to monitor the trajectory of the launcher and would reduce the launch costs, without threatening the initial safety requirements. This safety module will handle on-board navigation data measured by a GNSS receiver, among other sensors, in order to evaluate whether the launch is nominal. This paper deals with the issue of the localisation for an autonomous safety function: performances, robustness and integrity. Flight data from the A5 launcher trajectory for ATV5 launch that occurred on 29 July 2014, recorded by both CNES and ESA, have been extensively analysed by Airbus Defence and Space and it has highlighted the need for a more robust measurement chain at some specific events of the launch , when the boosters and the fairing are jettisoned especially. It is known and already demonstrated that stand alone GNSS receiver for safety trajectory does not fulfil all safety requirements because of loss of measurements during critical moments of the launch. Therefore, hybridization with an inertial measurements unit is necessary. The characteristics of this hybridization are determined and this solution is analysed based on both nominal ATV5 flight and a test case simulated on a highly non nominal launch trajectory. Last but not least, the realisation of a functional test bench is on-going in order to evaluate a complete navigation solution for the safety function.