A New Era for Navigation with LEOPNT in Europe: The Celeste IOD Mission and Recent Advances in Safran’s Skydel Simulator

This paper aims to provide an accessible and pedagogically-oriented overview of recent European advances in LEO-PNT by focusing on three complementary aspects: - The development of ESA' In-Orbit Demonstrator (IOD) mission, Celeste, and the Navigation Innovation and Support Programme (NAVISP). - The increasingly important role of GNSS/LEO-PNT simulation solutions in supporting the design, assessment and optimisation of these systems, with particular emphasis on Safran’s Skydel GNSS Simulation Software. - An applied use case on ionospheric modelling illustrating how simulation frameworks, like Skydel, must evolve to support the development of future multi-layer PNT architectures.