Solar Orbiter spacecraft instrument interface simulator and its applications for the STIX telescope tests

Solar Orbiter mission of European Space Agency, scheduled for launch in 2017, is designed to explore the Sun and the inner heliosphere. Its close, never achieved before by any other spacecraft, approach to the Sun as well as ten remote-sensing and in-situ on board instruments will allow obtaining unique solar science data. The Spectrometer Telescope for Imaging X-rays (STIX) is one of them. Its measurements of solar thermal and non-thermal hard X-ray emissions from ~4 to 150 keV will play an important role to achieve mission's major science goals. The Spacecraft Instrument Interface Simulator (SIIS) is specified as a part of Electrical Ground Support Equipment with the aim to provide a tool for power interface and telemetry/telecommand electrical and data protocol validation during the delivery phase of STIX instrument for spacecraft integration. It is designed to be used during the instrument development and test phases of onboard algorithms, too. Brief overview of SIIS use and performance for these purposes is given in this work.