Optimal design of multi-stage satellites subject to life analysis

A mission to the asteroid 4386 Lust serves as an example to demonstrate the performance of the integrated design optimization for multi-stage satellites. The problem is treated in the framework of the optimal control of a single and complete system described by a large number of differential-algebraic equations. The problem of optimal control theory is transformed into a multi-point boundary value problem for a system of highly nonlinear differential-algebraic equations. Boundary conditions and interior point conditions are either directly derived from the formulation of the problem or obtained from the variations of the extended functional. The components of the system are described by model functions and parameters that fit into this framework in a natural way. Scientific and technological constraints are included as state and control constraints and interior point conditions. The numerical solution of the boundary-value problem is by the advanced multiple shooting method JANUS for differential-algebraic systems, which allows a new order of magnitude in system complexity to be handled efficiently. Additionally, the results of lifetime analysis are fully considered in the optimization procedure; this leads to significant modifications compared to the traditional design of a satellite. Payload optimization yields a dual-stage satellite with a cluster of ion thrusters in the first and Hydrazine thrusters in the second stage.