Design of the Optimal Trajectory for Multi-Payload Multi-Orbit Injection of an Upper Stage
Creators: name:  I. ALFORJA RUIZ 
name:   M. LAVAGNA 
Publisher: name: Proceedings of  the 9th European Conference for Aerospace Sciences. Lille, France, 27 June - 1 July, 2022
Year: 2022
Subjects: FLIGHT DYNAMICS
GNC
AVIONICS
OPTIMIZATION

description: The continuously growing space sector has brought with it an increase in the number of missions planned for the following years. This rapid escalation is also promoted by the higher interest and capabilities of production of smaller satellites, and the higher attraction towards constellation missions. Nevertheless, this development in the industry entails an increased demand in the space access, and thus in the number of necessary launches per year, showing a tendency beyond the current logistic capabilities of space transport systems. The spotlight has been then put on the need for new solutions for space launchers, which can accommodate this demand in the most economical and ecological manner. Considering this new launcher market situation, the capability to inject several payloads into their respective differentiated orbits shows itself to be an interesting solution. In this manner, the number of launches per year would be reduced, while keeping up with the missions growth tendency. Nevertheless, this multiple orbit visitation demands on several orbital manoeuvres, whose definition cannot be determined straight forward and requires of careful analysis. In fact, the design of the multi-payload injection trajectory requires the decision on the sequential order of orbits to be visited, as well as on the variables related to the individual transfers. The current paper proposes a tool that can solve such a complex multiple transfer problem. The definition of this trajectory is established as a bi-objective optimization problem, in which both the consumption of fuel mass and the overall mission time are set to be minimized. The tool provides a set of optimal solutions by addressing the sequential and the transfers problems separately in a bi-level structure, in a way that the inner loop (solving the set of manoeuvres for a certain sequence) is used as the cost function for the outer loop, optimizing the order of visitation. Special focus is put in the definition of the algorithms to be used for both problems, based on their computational speed and accuracy. In such a way, social-knowledge-based algorithms are selected, using an Ant Colony-based strategy for the sequential problem, and a multi-objective Particle Swarm Optimization (PSO) strategy for the transfer problem. These transfers are assumed to be impulsive Lambert targeting manoeuvres, providing a good estimate of true continuous control both in terms of timing and fuel consumption, although alternative strategies are included for higher consumption manoeuvres. An analysis on different missions is carried out, providing an insight on the performance of the tool, as well as on the viability of different case scenarios. The result is a flexible tool that can accommodate a wide variety of mission scenarios, while being compatible with both constellation missions and heterogeneous multi-payload deployments in which the insertion orbits and mass properties differ. Such an architecture will enable the definition of a more detailed optimal trajectory definition, providing an insight on the Guidance, Control and Navigation system requirements for an upper stage with multi-orbit multi-payload capabilities. This study lies within the ASCenSIon (Advancing Space Access Capabilities - Reusability and Multiple Satellite Injection) project, an Innovative Training Network (ITN) funded within H2020.