First in-orbit results of the QUBE mission hosting a laser communication terminal for experiments towards quantum key distribution from CubeSats

Kurzfassung

Free-space optical communication is an inherently secure and robust method to transfer information over large distances. To increase the level of secure communication even further, it marks the base for quantum key distribution, a tap-proof encryption method based on the principles of quantum mechanics. The ever-increasing number of small spacecrafts and the growing global threats require secure communication channels, robust against jamming, spoofing, and eavesdropping. Classical radio-frequency communication is, due to its physical properties and its wide-angled beacons sensitive for unwanted interceptions. The technology transfer of laser communication to small satellites like CubeSats provides solutions to overcome the limitations of classical communication, but it comes with the necessity of very precise and accurate pointing. To demonstrate quantum key distribution technologies on a CubeSat, the project QUBE has the goal to verify two experimental quantum sources which signals are transmitted over an optical link from a 3U CubeSat. Two quantum sources, developed by the Ludwig-Maximilian University of Munich and the FriedrichAlexander University in Erlangen, are coupled into the laser communication terminal OSIRIS4QUBE, an evolution of OSIRIS4CubeSat developed by the German Aerospace Center. These systems are integrated into the 3U CubeSat QUBE built by the Center for Telematics. Establishing an optical connection between the laser terminal and the optical ground station requires precise and accurate pointing of the satellite. This task is handled by a high-precision attitude determination and control system. This paper presents the first results of the launch and early orbit phase of the QUBE mission. It highlights the achievements of the attitude determination and control system and the commissioning of the OSIRIS4QUBE terminal. The paper focuses on these two topics and explicitly excludes the results of the experimental quantum payloads.