Design and Verification of the GNC for the European ExoMars EDL Demonstrator

The EXOMARS program, consists of two missions to Mars launched in 2016 and 2018 launch opportunities. These missions are part of a large international cooperarion with NASA. The ExoMars 2016 mission is ESA-led and will launch to Mars the Trace Gas Orbiter (TGO) devoted both to perform investigations on the Martian atmospheric trace gases and to provide relay service to Mars surface assets and the Entry, Descent and Landing Demonstrator Module (EDM). The EDM has the European technological objective to perfoem the Endtry, Descent and Landing of a payload on the surface of Mars. ThalesAlenia Space Italy, the prime contractor of t he ExoMars program, is responsible of the EDL Demonstrator Module, including the Guidance Navigation & Control (GNC) subsystem and the EDL End-to-End (E2E) Simulator developed for the verification and validation of the EDL performance, This paper outlines the process of requirement definition, design, verification and simulation app lied for the ExoMars EDM GNC design during the phase B of the program . GNCsys ϑ maximum half-conical angular error admitted, at sys tem level, at touchdown due to GNC errors req req ω ϑ , maximum half-conical angular and rate errors admit ted, at GNC subsystem level, at RCS Switch-Off Trigger (SOT) C C ω ϑ , portion of the axial angular error and angular rat e admitted at SOT to be allocated to Control N ϑ , N ω portion of the axial angular and angular rate erro rs admitted at SOT to be allocated to Navigation G ϑ , G ω portion of the axial angular and angular rate erro rs admitted at SOT to be allocated to Guidance vimpact V Maximum vertical velocity admitted, at system leve l, at touchdown, due to GNC errors GNCsys v GNCsys V h , Δ Maximum error in altitude and in vertical velocity admitted, at system level, at SOT req h req v req V