Solar Orbiter Thermal Design Drivers and Verification Approach

Abstract

The Solar Orbiter mission takes the next step in the Sun’s observation from space. The mission profile and instrumentation enables the exploration of the uncharted innermost region of the solar system, observations of Sun from as close as 0.28AU and fly-bys tuned to the Sun’s rotation rate to provide a co-rotating vantage point of the Sun’s surface. Observation of the Sun’s Polar Regions at heliographic latitudes greater than 34° will also be achieved by an increase in the inclination of successive orbits. The Solar Orbiter spacecraft (Figure 1) will gather data and provide observations of the Sun using a suite of remote sensing and insitu instruments located within the spacecraft platform. The operation of these payloads requires the provision of heat rejection from high temperature sun exposed components while providing passive cooling to detectors down to -60°C. A combination of traditional passive and active thermal design techniques protects the platform subassembly throughout all mission environments, and reduces the reliance upon less proven high temperature technologies. The thermal design is driven by the thermal environment experienced at 0.28AU. A high temperature heat shield protects the spacecraft and instruments from the extreme solar flux of up to 12.75 solar constants, while incorporating feedthroughs to provide remote sensing instruments with a view of the Sun. While the heat shield provides a benign thermal environment of the spacecraft platform, consideration for the interaction with the sun exposed appendages such as the solar array is required. This paper discusses the thermal design drivers and verification strategy of the Solar Orbiter Spacecraft and its constituent subassemblies in the lead up to the system PDR. Consideration is given to the different thermal environments experienced during operation and how these affect the design and the steps required to enact the verification of the overall performance of the spacecraft thermal subsystem. Nomenclature AOCS: Attitude and Orbit Control System