ASTOS is a tool dedicated to mission analysis, Trajectory optimization, vehicle design and simulation for space scenarios, i.e. launch, re-entry missions, orbit transfers, Earth observation, navigation, coverage and re-entry safety assessments. It solves Aerospace problems with a data driven interface and automatic initial guesses. Since 1989, with the support of the European Space Agency, it has developed, and improved this trajectory optimization environment to compute optimal trajectories for a variety of complex multi-phase Optimal control problems. ASTOS is being extensively used at ESA and aerospace industry community to calculate mission analysis, optimal launch and entry trajectories and was one of the tools used by ESA to assess the risk due to the ATV 'Jules Verne' re-entry. ASTO