3. Conclusion

The design of a launcher requires a global, multi-disciplinary approach, integrating the couplings between staging and trajectory. The reuse of the first stage is an important avenue for improvement. The trajectory comprises an ascent branch to orbit and a return branch. The first stage must keep the right amount of propellant for its return and landing maneuvers, which accentuates the coupling between staging and trajectory. The study of these configurations and their versatility poses new challenges and stimulates the improvement of optimization methods.