This project was submitted by the DLR institute for Communications and Navigation (IKN) following a call for tenders by ESA. The aim of the project is to investigate and technically detail the possibilities for experimental use of optical technology (clocks, frequency comb, laser communications and laser distance determination) on the Galileo transition satellites as part of a phase A study. In agreement with the Institute for Communications and Navigation, the Galileo Competence Center is to take over the project management here. Industrial partners include the Bavarian-based company Menlo Systems and the Baden-Württemberg company TESAT.