Modular Software Architecture for Fully Coupled Spacecraft Simulations

Computer simulations of spacecraft dynamics are widely used in industry and academia to predict how spacecraft will behave during proposed mission concepts. Current technology and performance requirements have placed pressure on simulations to be increasingly more representative of the environment and the physics that spacecraft will encounter. This results in increasingly complex computer simulations. Designing the software architecture in a modular way is a crucial step to allow for ease of testing, maintaining, and scaling of the software code base. However, for complex spacecraft modeling including flexible or multibody dynamics, modularizing the software is not a trivial task because the resulting equations of motion are fully coupled nonlinear equations. In this paper, a software architecture is presented for creating complex fully coupled spacecraft simulations with a modular framework. The architecture provides a solution to these common issues seen in dynamics modeling. The modularization of the fully coupled equations of motion is completed by solving the complex equations analytically such that the spacecraft rigidbody translational and rotational accelerations are solved for first and the other second-order state derivatives are found later. This architecture is implemented in the Basilisk astrodynamics software package and is a fully tested example of the proposed software architecture.