The EAGLE-1 mission aims to develop Europe's first sovereign, end-to-end space-based quantum key distribution (QKD) system. The mission is led by the European Space Agency (ESA) and SES in collaboration with several European National Space Agencies and private partners. The state-of-the-art QKD system will consist of a payload on board the EAGLE-1 low Earth orbit (LEO) satellite, optical ground stations, quantum operational networks, and key management system. The EAGLE-1 mission represents a major step for next-generation quantum communication infrastructures, delivering valuable technical results and mission data. The Institute of Communications and Navigation (IKN) of the German Aerospace Center (DLR) is a key partner in the EAGLE-1 mission and is involved in the research and development of elements in both space and ground segments. Here we report on the development of the QKD transmitter, a vital part of the QKD payload, and the customization of the Optical Ground Station Oberpfaffenhofen (OGS-OP) to conduct the IOT phase of EAGLE-1. For the space segment, DLR-IKN is in charge of the design of the QKD transmitter, including the development of the software and firmware. This transmitter generates quantum states which are used to implement a QKD protocol based on an optical signal, that will be transmitted to ground. For the ground segment, The OGS-OP will serve as the in-orbit testing ground station for EAGLE-1. Building upon the expertise with a range of satellites for quantum communication, as well as new implementations, OGS-OP will validate the performance of the payload, optical link and QKD system for the first time. We present the main developments of OGS-OP for the mission, which includes the implementation of an upgraded adaptive optics system to correct for atmospheric distortions and optimize the coupling of the incoming light into a single mode optical fiber.
The EAGLE-1 mission aims to develop Europe's first sovereign, end-to-end space-based quantum key distribution (QKD) system. The mission is led by the European Space Agency (ESA) and SES in collaboration with several European National Space Agencies and private partners. The state-of-the-art QKD system will consist of a payload on board the EAGLE-1 low Earth orbit (LEO) satellite, optical ground stations, quantum operational networks, and key management system. The EAGLE-1 mission represents a major step for next-generation quantum communication infrastructures, delivering valuable technical results and mission data. The Institute of Communications and Navigation (IKN) of the German Aerospace Center (DLR) is a key partner in the EAGLE-1 mission and is involved in the research and development of elements in both space and ground segments. Here we report on the development of the QKD transmitter, a vital part of the QKD payload, and the customization of the Optical Ground Station Oberpfaffenhofen (OGS-OP) to conduct the IOT phase of EAGLE-1. For the space segment, DLR-IKN is in charge of the design of the QKD transmitter, including the development of the software and firmware. This transmitter generates quantum states which are used to implement a QKD protocol based on an optical signal, that will be transmitted to ground. For the ground segment, The OGS-OP will serve as the in-orbit testing ground station for EAGLE-1. Building upon the expertise with a range of satellites for quantum communication, as well as new implementations, OGS-OP will validate the performance of the payload, optical link and QKD system for the first time. We present the main developments of OGS-OP for the mission, which includes the implementation of an upgraded adaptive optics system to correct for atmospheric distortions and optimize the coupling of the incoming light into a single mode optical fiber.
The EAGLE-1 mission aims to deliver Europe’s first autonomous space based quantum key distribution (QKD) system launching the EAGLE-1 satellite in 2026. A key element of this demonstration mission is the development and space qualification of a QKD transmitter, essential for enabling secure quantum communications. This paper presents the subsystem-level design, component qualification, system calibration, and functional testing of the QKD transmitter developed by the Institute of Communications and Navigation (KN) of the German Aerospace Center (DLR). The QKD transmitter is responsible for converting quantum key information into an optical signal for transmission to ground. The quantum key and QKD protocol is based on a quantum random number generator (QRNG) and the key bits are encoded in single photons. The transmitter hardware consists of various electrical and optical components, including modulators, attenuators, amplifiers, and passive elements. We discuss component selection criteria, as well as vibration and shock testing to verify launch resilience and thermal vacuum testing to assess operational stability under space conditions. One of the key challenges is the time and bias drift of critical components, which occurs after system boot-up and varies with temperature and time. These drifts directly affect the timing, amplitude, and phase of the optical signal, impacting overall QKD performance. We present the design of the calibration methodologies which ensure autonomous calibration of the transmitter in orbit, which provides the system stability required to adhere to the QKD protocol requirements. Finally, we describe the laboratory tests assessing quantum bit error rates (QBER).
The satellite mission EAGLE-1 represents an important step towards a future pan-European secure Quantum Key Distribution (QKD) network. The public-private partnership behind the mission consists of a consortium of universities, research institutes, and companies partially funded by ESA, the European Union, and supported by national delegations. This unique combination of academic partners and industry facilitates a swift knowledge transfer from basic research to commercial application. Within the consortium, Tesat-Spacecom (TESAT) is responsible for developing and integrating the payload assembly of the low-earth orbit EAGLE-1 satellite. In addition, TESAT provides the SCOT80 laser terminal with minor adaptations for the mission. Here, we report on the status, technical aspects and TESATs contribution to the satellite-to-ground prepare-and-measure QKD mission.
The Institute of Communication and Navigation at the German Aerospace Center (DLR) hosts the Optical Ground Station Oberpfaffenhofen (OGSOP). The station is operating with an 80cm primary mirror telescope, including a Nasmyth configuration. These were guiding light to several different experimental ports at the Ground Station itself, as well as a free space optical Coudé-Path, leading onto an optical table inside the laboratory below the station. After the commissioning of the OGSOP (2021 – 2023) various projects and free space laser communication experiments have been conducted. OGSOP approved operations including data downlinks from the low orbit satellites Flying Laptop, CubeL and QUBE. Experiments with Alphasat (GEO stationary platform) were also carried out as well as an aircraft link campaign in the frame of QuNET project. The gained experiences and lessons learned of all these missions led to further development and upgrades of the OGSOP, especially from classical laser communication towards the direction of Quantum Key Distribution (QKD). The upgraded OGSOP and its peripheric systems are a designated test bed for QKD [1][2]. The QKD precursor Missions QUBE-I (launch August 2024) is already in the phase of an ongoing linking campaign at OGSOP. From first light to scientific experiments, the OGSOP could already proof its capability to support this type of optical free space satellite communication missions. The receiving Coudé-Path and system PUMUQL (Prototyping Unit for Modulated User-data and Quantum Links) was integrated for the quantum light, as well as an adaptive optics system in development. The follow up mission QUBE-II is also already launched (May 2026) and currently in its finally LEOP phase, it will will go into first tests around autumn 2026 at OGSOP. The preparation for Eagle-1 is a main part of the work and development for the optical ground station. QKD up- and downlink path is redesigned, implemented and brought into operational service. The growth of the number of projects dropping into the OGSOP was one of the reasons to go from classical project-based time by time mission support to a matrix like solution for multi mission support and operations. An established configuration management, new commanding, booking and preparation processes are assisting the whole organization. Following an overview of the current status of the OGS, the ongoing projects (QUBE, Eagle-1, QuNET, and more) will be given. A description of the ground stations infrastructure and support facilities will be represented in relation to different project requirements and missions.
Laser communication technology, especially QKD (Quantum Key Distribution), is coming more and more into practical operations. It is a maturing technology that enables the distribution of cryptographic key between two remote parties [1][3] for secure communication even in presence of quantum computers[3]. To demonstrate this technology DLR is part of the QUBE project to have a precursor mission for QKD from CubeSats in orbit as well as hosting and operating the ground-based counterpart the Optical Ground Station Oberpfaffenhofen (OGSOP).The OGS is equipped with an 80cm primary mirror, a Coudé path with optical bench, adaptive optics system, fiber coupling and a single photon detector. The ground station already performed successful downlinks from low Earth orbit (LEO) (Flying Laptop, CubeL and others) and geostationary platforms (Alphasat, Project BayernQSat), as well as aircrafts (Project QuNET) [4][11][13].In the last year the ground station was upgraded from its basic configuration to adapt for multi-mission support and QKD experiments. Several features were integrated and upgraded at the telescope, in the Coudé path and on the optical bench. The focus of the upgrades was to connect the OGSOP (Optical Ground Station Oberpfaffenhofen) with the satellite QUBE. The target of compatibility could be achieved and improved from OGS side.Knowledge from ground-to-ground-tests were considered to rebuild the receiving setups in an improved and more operational way. The QUBE satellite contains an optical terminal designed and developed by DLR to transmit two experimental quantum signals over the optical link. These sources were developed by the Ludwig-Maximilian University (LMU) of Munich and the Friedrich-Alexander University (FAU) in Erlangen.On May the 2nd 2025 the OGSOP was able to catch the first light from QUBE and establish a link between both sides[2]. This started the optical communication commissioning phase of the satellite, including the classical communication terminal and the quantum light sources. This paper describes the entire setup, from satellite to ground detector, and presents the key achievements so far.
A worldwide growing interest in fast and secure data communications pushes technology development along two lines. While fast communications can be realized using laser communications in fiber and free-space, inherently secure communications can be achieved using quantum key distribution (QKD). By combining both technologies in a single device, many synergies can be exploited, therefore reducing size, weight and power of future systems. In recent experiments we demonstrated quantum communications over large distances as well as between an aircraft and a ground station which proved the feasibility of QKD between moving partners. Satellites thus may be used as trusted nodes in combination with QKD receiver stations on ground, thereby enabling fast and secure communications on a global scale. We discuss the previous experiment with emphasis on necessary developments to be done and corresponding ongoing research work of German Aerospace Center (DLR) and Ludwig Maximilians University Munich (LMU). DLR is performing research on satellite and ground terminals for the high-rate laser communication component, which are enabling technologies for the QKD link. We describe the concept and hardware of three generations of OSIRIS (Optical High Speed Infrared Link System) laser communication terminals for low Earth orbiting satellites. The first type applies laser beam pointing solely based on classical satellite control, the second uses an optical feedback to the satellite bus and the third, currently being in design phase, comprises of a special coarse pointing assembly to control beam direction independent of satellite orientation. Ongoing work also targets optical terminals for CubeSats. A further increase of beam pointing accuracy can be achieved with a fine pointing assembly. Two ground stations will be available for future testing, an advanced stationary ground station and a transportable ground station. In parallel the LMU QKD source size will be reduced by more than an order of magnitude thereby simplifying its integration into future free-space optical communication links with CubeSats.
Quantum Key Distribution (QKD) is a promising method to guarantee future-proof, information theoretic security. Since optical fibers have an exponential loss with distance, satellite-based QKD solutions are being developed in order to realize long-distance links. Therefore, Optical Ground Stations for QKD (QKD-OGS) need to be designed to enable quantum communication with satellites. Different link configurations will result in different integration options of the QKD-OGS in the terrestrial fiber network and therefore impact its performance. Applicable integration options must be identified and trade-off analysis conducted at the architecture, system and sub-system level. The reference scenario is a Low Earth Orbit (LEO) downlink configuration employing a decoy-state BB84 protocol with polarization encoded qubits at 1550 nm wavelength. The satellite acts as trusted node for implementation of the key distribution between two parties on ground. Furthermore, only direct connections from the satellite to the end-users are considered, i.e. the QKD-OGS does not serve as a trusted-node relay. This results in the selection of three main integration concepts: first, a free-space, end-user QKD-OGS which is located directly at the end-user where the quantum signal is measured directly behind the receiver telescope in free-space; second, a fiber-coupled, end-user QKD-OGS where the quantum signal is coupled into a single-mode fiber and guided to a co-located server room hosting the QKD Receiver system; third, a fiber-coupled, provider QKD-OGS, which reaches several end-users by using a local fiber network. In order to evaluate these three concepts, the comparison parameter is defined to be an estimated factor of suppliable end-users. The estimated comparison factor shows that the fiber-coupled, enduser QKD-OGS can supply 6.7 times more end users than the free-space, end-user QKD-OGS. The fiber-coupled, end-user QKD-OGS can supply 129.7 times more end-users than the free-space, end-user QKD-OGS.