Solar Orbiter Solar Array - Exceptional Design for a Hot Mission

Abstract

The Solar Orbiter (SolO) mission is a joint ESA and NASA interdisciplinary mission to study the sun. The spacecraft will orbit the sun in a moderately elliptical orbit. It will, amongst other things, investigate the near sun heliosphere environment and its magnetized atmosphere by using in-situ measurements very close to the sun to improve our understanding of solar and heliospheric processes. The Solar Orbiter spacecraft will approach the sun close to 0.28 AU. While the Solar Orbiter solar array design is, to a large extent, based on the design of the BepiColombo Mercury Planetary Orbiter solar array, the thermal shields and rear side foil is very specific for this mission. Solar Orbiter is equipped with unique and highly sensitive remote-sensing and in-situ sensors which require limiting the radiated electromagnetic emission. Additionally, the mission requires that optical and thermal reflections to the spacecraft are minimized. Some solar array heat shields have to withstand temperatures of more than 450°C, whereas others are designed such that the temperature is below 270°C to keep the structures within their qualified temperature range and simultaneously fulfil sunlight reflection requirements. This paper describes the Solar Orbiter solar array design in general and the thermal shield design in detail with its challenges to cope both the thermal and stray light requirements.