QUBE 2

QUBE 2 [Zentrum für Telematik]

QUBE 2 is a German 8U CubeSat quantum communications technology demonstrator developed by Kongsberg NanoAvionics for the German Federal Ministry of Research, Technology and Space (BMFTR). The satellite is intended to demonstrate the first quantum key exchange between a CubeSat and a ground station, using a compact optical communications terminal to support future secure global communications networks based on quantum key distribution (QKD).

The mission is part of the German national QUBE quantum communications programme. The satellite system is managed by Zentrum für Telematik Würzburg, while OHB System AG serves as overall system coordinator. Payload contributions are provided by the German Aerospace Center, Ludwig Maximilian University of Munich, and Friedrich-Alexander-Universität Erlangen-Nürnberg.

QUBE II follows the earlier QUBE mission, in which miniature quantum key generation technologies were integrated into a CubeSat platform together with optical communications systems. The predecessor mission tested the functionality and survivability of miniaturized quantum communications hardware under space conditions in preparation for operational QKD applications.

The QUBE II spacecraft introduces upgraded quantum communication components and new optical communications capabilities required for practical quantum key generation. A major focus of the mission is reducing optical channel losses between the satellite and the ground station. To achieve this, the spacecraft carries a larger-aperture optical telescope for transmission of quantum signals. The mission will also establish an optical uplink from the ground station to the satellite for the first time within the QUBE programme. This bidirectional optical communications link is required to support the high-data-rate classical communications channel needed by QKD protocols.

The optical communications payload is based on the OSIRIS4CubeSat terminal developed by the German Aerospace Center. For QUBE II, the terminal is extended with additional receiver functionality to support bidirectional communications during quantum key generation operations. The spacecraft uses a modular CubeSat platform derived from the earlier QUBE mission architecture. Because of the enlarged optical aperture and expanded payload functions, the spacecraft size increases from the 3U configuration used by QUBE to an 8U CubeSat form factor.