Open GL–Open CL Solar Radiation Pressure Modeling with Time-Varying Spacecraft Geometries

Abstract

A method for the fast computation of spacecraft force and torque due to solar radiation pressure (SRP) is presented. A faceted model is employed that tracks which elements of a time-varying geometry are exposed to the sunlight, but sunlight reflections are not modeled. The method uses the highly parallel execution capabilities of commodity graphics processing unit (GPU) and the Open Graphics Library (OpenGL) and Open Compute Language (OpenCL) to render a spacecraft mesh on the GPU. A custom-developed OpenGL render pipeline computes the per-model facet SRP forces and torques that are summed on the GPU before the resultant spacecraft force and torque vectors are copied back to the CPU bound process. The process is validated on spherical and cubic test shapes. The evaluation accommodates spacecraft self-shadowing and is capable of accounting for arbitrary spacecraft articulation. Material properties are encoded with the model to provide realistic specular, diffuse, and absorption surface light interactions. Numerical simulations illustrate the impact of geometric fidelity and articulated surfaces. The faceted OpenGL-OpenCL method is up to an order of magnitude faster on integrated GPU hardware than high-end graphics card as the process is not demanding on the GPU and benefits from the fast memory transfer of on-chip processors.