Speaker
Description
The Genesis mission, part of ESA’s FutureNAV programme, aims at significantly improving the accuracy and stability of the International Terrestrial Reference Frame (ITRF), the foundation of satellite navigation and Earth science. This extreme accuracy will be achieved by co-locating the four main geodetic techniques: GNSS, very-long-baseline interferometry (VLBI), satellite laser ranging and DORIS, onboard a single well-calibrated satellite, all synchronized by an ultra-stable oscillator (USO). These ambitious geodetic objectives impose demanding requirements on the spacecraft's thermal and thermo-mechanical design, making thermal control a key driver of the overall system architecture.
To achieve these objectives, a very particular mission and satellite thermo-mechanical configuration had to be developed. Firstly, the Genesis satellite will be placed on a 6000 km MEO orbit, one of the harshest radiation environments in Earth Orbit, significantly driving the satellite design. To mitigate radiation effects, the platform is built around thick aluminium honeycomb panels that provide radiation shielding. Where additional protection is required, dedicated radiation vaults enclose critical electronic units, significantly reducing their ability to dissipate heat. The selected orbit, combined with continuous nadir pointing and the absence of deployable or rotating solar arrays, results in large seasonal variations of solar illumination. Consequently, nearly every spacecraft face is exposed to direct solar flux at some point during the year, creating a particularly challenging thermal environment, critical to maintaining the ultra-stable oscillators and other thermally sensitive equipment within their stability requirements, going as low as 0.1 °C/min
The second major challenge of the Genesis mission is achieving the thermo-mechanical stability required to maintain the relative geometry of the scientific payloads throughout the mission lifetime. This requirement drove the development of an integrated thermal and structural architecture, in which the radiation-shielded electronics are housed within a dedicated platform module, while the antennas, instruments and star trackers are mounted on a payload module constructed entirely from CFRP sandwich panels. This configuration minimizes thermo-elastic effects and enables the dimensional stability required to meet the mission's geodetic performance. The design was supported by an extensive thermo-elastic distortion analysis campaign, comprising of hundreds of thermal load cases representative of all operational and environmental conditions throughout the mission lifetime, with the use of PySINAS as the main mapping tool.
The presentation will describe how stringent geodetic performance requirements drove the satellite’s thermal and thermo-mechanical architecture, with emphasis on the trade-offs between radiation shielding, thermal stability, heat rejection, materials and thermo-elastic performance.