Development of high-precision thermal models for the simulation of thermally induced perturbation effects

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Exact thermal modeling becomes increasingly important for high precision fundamental physics and geodesy missions where an exact knowledge of the thermal contributions to the disturbance budget is crucial for the mission success. We propose the development of a sophisticated tool for exact thermal modeling and exact thermal force/torque computation which can be applied to satellite missions or ground based experiments with high requirements on perturbation knowledge. Due to a surface-based computation approach it will also be possible to compute the disturbances originating from other influences like solar radiation pressure or space debris impact. As an application for the method, the thermal contribution of the Pioneer 10/11 probe to the disturbance budget will be computed thus using the method with a complete set of real flight telemetry data for an already flown deep space mission. This will lead to a better understanding of the thermal effects and clarifies the amount of anomalous acceleration that can be explained by thermal radiation.Likewise, the proposed method will be applied for other current high precision fundamental physics missions like LISA pathfinder, LISA and MICROSCOPE where an exact disturbance modeling is crucial for the mission success. Also geodesy missions will benefit from such an analysis. For LISA and Pioneer a sophisticated FE model will be developed and detailed thermal analysis will be conducted to improve the uncertainties in current thermal models [1, 2].The accuracy, handling and adaption of the ZARM Thermal Evaluation software (TES) for different mission concepts will be highly improved with respect to current tools for thermal modeling. Furthermore our approach is the first one that uses highly detailed FE models of the spacecraft geometries in a direct raytracing approach to compute the resulting forces and torques due to thermal radiation. As well as for the thermal modeling of spacebound experiments the method will be applicable to high precision experiments on Earth such as the Michelson-Morley experiment with optical resonators (see [3, 4] for details). Also the thermally induced disturbance forces on onboard sensors will be computable because each force fraction on each model surface is determined in the simulation process.