Accurate, GPU Accelerated Solar Radiation Pressure Modeling for Exo-Atmosphere Trajectory Simulation

For long-duration space flight, solar radiation pressure (SRP) can induce non-negligible forces on the space craft, requiring accurate modeling for the analysis of uncontrolled flight trajectories. These forces are the result of absorbed and reflected radiation on the spacecraft's surface, a phenomenon dependent on geometric and material properties. This paper describes the development, validation, and benchmarking of a high-fidelity solar radiation pressure model for fast and efficient simulation of the uncontrolled Earth approach flight of the Mars Sample Return Earth Entry System (MSR EES). The described SRP model is implemented in JPL's Dynamics and Real-Time Simulation (DARTS), and leverages DARTS's Inter-planetary Rendering for Imaging and Sensors (IRIS) for GPU-accelerated ray tracing of incident radiation on a space-craft. By leveraging ray tracing techniques, the SRP model includes the effect if detailed geometric features and spatially varying material properties, and accurately captures shadowing effects, supporting complex scenes such as non-convex geometries and occluding spacecraft. The SRP model calculates the force and moment induced by radiation on the vehicle as a function of absorbed and reflected radiation, accounting for per-ray incident lighting angle and inhomogeneous material properties. Additionally, since the ray-tracing of the SRP model is efficient, evaluation is performed throughout the simulation, allowing simulation of reconfigurable spacecraft geometries, such as the unfurling of solar panels. The applied force and moment and calculated through IRIS are incorporated in DARTS’ trajectory simulation, allowing analysis of absolute SRP effect for a given simulation or set of simulations via Monte Carlo simulation. In this contribution, we show how DARTS can carry out exo-atmosphere simulations to analyze the effect of radiation pres-sure. Along with the model, we describe the cross-validation of DARTS's SRP simulation with other tools. In addition to cross-validation, we include performance benchmarking of the DARTS exo-atmosphere simulation, showing 3 day trajectory simulation with SRP forces in less than 5 minutes on a single workstation with negligible error accumulation.