Fast and Accurate Re-Planning Tool Under Multidisciplinary Constraints Set

Abstract

Flexibility in mission operations is a requirement which is rapidly gaining relevance in future missions rq implementation. Indeed, it would add robustness against anomalies, increase the opportunistic science feasibility and the space assets potential exploitation at needs. However, it would turn into an increased effort for the Operation Centres to - consistently with the system constraints - re-plan and re-configure the shortterm mission plan shortly in advance. In most of the cases, re-planning involves numerically solving a set of non-linear equalityconstraints which includes -among others - orbitaldynamics while optimizing a set of given criteria, such as fuel consumption, time to target, actuators load, aspect angles and so on. The paper presents and discusses a tool, based mostly on analytical approach, developed with the aim of speeding up the solving time while decreasing the computational effort. Those performance are the more required whenever scenarios which involve either distributed systems – such as satellites in formation – or small satellites which still lack of dedicated ground segments with highly specialised mission control centers. Near-optimal solutions in large and non-monoconvex search spaces are easily detected. More in details, the exact 6 DoF kinematics of a controlled spacecraft is parametrized through the exploitation of a dedicated shape-based approach; the dynamics is then analytically computed, together with the admissible guidance to satisfy the imposed constraints set. Constraints set, which is typically mission dependent, can be easily tailored by the user, according to needs. The most relevant constraints, such as visibility (GS, target areas, etc) and path constraints (e.g. Sun or galatic center pointing and SAA avoidance) are easily implemented. The proposed tool is well suited for multidisciplinary and multi- objective 6 dof dynamics fast and robust guidance profile generation to support re-planning operations. Thanks to its flexibility it has successfully exploited in mission and operations design phases, both for single space asset and multi-satellites scenarios.

Paolo Lunghi

Assistant Professor of Aerospace Systems

Aiming for autonomous Guidance, Navigation, and Control for spacecraft.