1. Center of Applied Space Technology and Microgravity (ZARM), University of Bremen, Am Fallturm, 28359 Bremen, Germany
2. Institut für Quantenoptik, Leibniz Universität Hannover, Welfengarten 1, 30167 Hannover, Germany
3. DLR Institute for Space Systems, Robert-Hooke-Str. 7, 28359 Bremen, Germany