Design and Test of a Concept for Solar Orbiter Heat Shield

Solar Orbiter is the next solar-heliospheric mission in the Science Programme of ESA. The mission will provide the next major step forward in the exploration of the Sun and the heliosphere to investigate many of the fundamental problems in solar and heliospheric science. The near-Sun phase of the mission will enable the spacecraft to approach the Sun as close as 0.22 AU during part of its orbit, thereby permitting observations from a quasi heliosynchronous vantage point. During the out-of-ecliptic phase of the mission, Solar Orbiter will reach higher solar latitudes, up to 34° close to the end of the mission, to observe also the polar regions of the sun. The 3 axis stabilized spacecraft will carry two groups of scientific instruments: In-situ instruments to study the local environment and Remote Sensing instruments to observe the sun, therefore the latter will require apertures in the face oriented towards the Sun. One of the main design drivers for Solar Orbiter is the thermal environment, determined by the solar constant which reaches up to 28500 W/m2. All exposed items as antennae and solar arrays will be tailored to these conditions, and the spacecraft body will remain protected behind a sunshield, housing also the apertures of the Remote Sensing instruments. The sunshield was the subject of two Technology Demonstration Activities (TDA) awarded by ESA to Astrium and Thales Alenia Space, aimed at designing the sunshield, developing the manufacturing technologies and the test method to verify the performances under simulated flight conditions at 0.22 AU. The activities were completed in late 2007. At the end of 2007 ESA selected Astrium as the system contractor responsible for the mission; a Phase B2 (definition phase) which is about to start, will mature the design and the technologies. TAS will be involved in the areas of power, transmission and thermal subsystems. This paper describes the Thales Alenia Space spacecraft design concept and in particular the heat shield design, test, correlation and the extrapolation of test results to flight conditions.Cross Reference: