In-depth theoretical analyses have been performed to identify relevant failure scenarios and conditions for testing. This included a solar array design review, orbit environment simulations and hypervelocity impact effects evaluation.
More than 60 hypervelocity impact experiments have been performed using the fastest two-stage light gas gun at Fraunhofer EMI and the plasma-dynamic accelerator located at the Technische Universität München. Those facilities complement each other with regard to the projectile size from the micron to the millimetre range, while both provide hypervelocity capabilities that are unique in Europe.
Representative solar array test samples have been designed and manufactured at Astrium in Ottobrunn. Components and layout represent state-of-the-art solar arrays of European GEO telecommunication platforms. This includes GaAs multi-junction cells and modern substrate technologies.
Representative operational conditions have been established by a dedicated test set-up, which simulated the electrical output and dynamic behaviour of a solar panel at test sample level. In addition, high vacuum conditions have been established in the target chambers of the accelerators in order to allow for neglecting plasma interactions with the residual atmosphere.
Comprehensive diagnostics have been implemented in the test set-up to monitor sample operational parameters and acquire data of impact processes and effects for scientific exploitation. In view of the importance of the impact plasma for the failure processes, special plasma diagnostics have been applied, comprising emission spectroscopy, charge yield measurements, electrical plasma probing and high-speed imaging.