Thermal and mechanical analyses for the NSAT-1 phase B study

The Norwegian Defence Research Establishment (FFI) and industry partners are looking into a possible development of a micro satellite system (NSAT-1) with an X-band vessel-detector antenna to geolocation vessels for maritime surveillance. To achieve high geolocation accuracy, the pointing direction of the vessel-detector antenna has to be known with an extreme accuracy. A star tracker is mounted to the backside of the antenna panel to determine the exact pointing direction of the antenna. In this phase B study, it is focused on the antenna panel, the star tracker assembly and the bracket connecting them. The thermal and mechanical requirements set to this system are critical to the concept. Attention is also paid to the loadcases, describing detailed thermal loads both during power generation and observation. This report reveals the thermal and mechanical analyses for the NSAT-1 phase B study, and a discussion of the results. In this work a mechanical and thermal model is created, view factors and loadcases are defined, and material parameters are established. In general, the results show that the NSAT-1 could be realized from a thermal-mechanical point of view, using the suggested design. However the requirement of 1.0 E-3 deg maximum variation of the angle between the optical axis of the star tracker and the antenna boresight are too strict, and must be negotiated in the total error budget.