The Thermal Balance/Thermal Vacuum Test of BepiColombo Mercury Planetary Orbiter

Abstract

BepiColombo is the first European mission to Mercury. It mainly consists of two separate spacecraft which will orbit the planet: Mercury Magnetosphaeric Orbiter (MMO), provided by the Japanese Space Agency, and Mercury Planetary Orbiter (MPO), provided by the European Space Agency, plus a dedicated module, Mercury Transport Module (MTM), which will provide the transfer from Earth to Mercury. MPO, the subject of this paper, is the European scientific contribution to the BepiColombo mission. Its orbit around Mercury will be 3-axis stabilized, planet oriented, with a planned lifetime of 1 year, and a possible 1-year extension. The mission will perform a comprehensive study on Mercury, by means of several instruments, including a laser altimeter, different types of spectrometers, a magnetometer and radio science experiments. To verify both the MPO function in vacuum under extreme temperature conditions and the capability of its thermal design to withstand the extremely challenging thermal environment that it will face in its orbit around Mercury, a specific Thermal Balance/Thermal Vacuum (TB/TV) test has been performed in November 2014 in ESTEC Large Space Simulator (LSS). Test phases at different intensity level, from 1 Solar Constant to 8 Solar Constants, have been conducted. Illumination has been performed from several directions to cover different orbit illumination conditions. The aim of this paper is to report the TB/TV that has been performed on the MPO, including test setup, problems occurred during the test, evaluation of the test results and correlation with the predictions of the Thermal Mathematical Model.