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.
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.
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 QUBE-I mission is a technology demonstrator mission for novel building-blocks for satellite-based quantum-key-distribution (QKD). The mission aims to test three highly integrated optical payloads, a quantum random number generator and two transmitters for polarization and phase encoded quantum states as a precursor mission for the first QKD demonstration from a CubeSat. The QKD sources are connected to, and are integrated together with the Optical Space Infrared Downlink System (OSIRIS) for QUBE (O4Q) in a 3U CubeSat. One of the mission's primary challenges is achieving a precise and accurate pointing of the O4Q with an error margin of less than 1° towards the optical ground station (OGS). Additionally, conducting the experiments presents several operational challenges, such as the need for precise orbital elements to track the satellite with the OGS and safety mechanisms to protect the Sunsensitive components of the satellite. Following the launch on 16th August 2024, we conducted an extensive commissioning phase to test all subsystems, payload components, and operational procedures. This paper provides insights and results from QUBE-I's first year in orbit, highlighting lessons learned from integrating multiple complex payload systems into a 3U CubeSat platform. Starting with communication establishment, we present the ground segment and operations capabilities. We elaborate on the use of flexible on-board scripting and recording mechanisms provided by the satellite's flight software stack for operations. An effective review, test, and deployment procedure was established to balance risk mitigation and agile operation planning. We present results of extensive tests conducted for the crucial attitude determination and control system (ADCS), including actuator verification, spin-up and detumbling tests, in-orbit sensor calibration procedures, and the evaluation of various pointing modes, such as the fine pointing mode required for the experiments. Besides that, we give insights in the actual performance of the experimental and scientific payloads after their commissioning. A big milestone marked the successful test of the operational procedure for the QKD experiments. This includes the timely provision of precise orbit determination to the OGS for tracking. In addition, the ADCS needs to prepare the fine pointing mode accordingly and the experiment needs to be started autonomously before actual contact. Flexibly selectable on-board recordings can be downloaded after the experiments for evaluation. As expected, the technical complexity of the QUBE-I mission resulted in a challenging first year of operation. With this paper, we aim to share our experiences and contribute our insights to the space community.
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.
Satellite-based Quantum Key Distribution (QKD) can be used to deliver information-theoretically secure keys for cryptographic applications, no matter where end-users are located. Several space missions using this concept have shown feasibility of systems and component technologies. The QUBE-II mission, with a planned launch in Spring 2026, uses an economic CubeSat platform to show the possibility of a global secure communication by simple means. This paper presents the optical system design of the QUBE-II laser communication terminal (LCT). It is based on the previous developments for the CubeL mission (launched in 2021), for CubeISL, and for the precursor mission QUBE-I (launched in 2024). The 2.5U LCT is integrated into an 8U CubeSat and serves as transmit system for two Alice modules operating at 850 nm and in optical L-band1, 2 respectively. At the same time, bi-directional classical links are used for link acquisition, tracking, and data transmission. With its 85 mm aperture and an 800 mm receiver telescope on the ground station, the antenna gain is sufficiently high enough to perform QKD links. The LCT’s optical system is designed based on a commercially available reflective telescope in combination with custom-designed lenses. It integrates several fiber-optical and electrical components for wavelength combination, wavelength splitting, tracking, and uplink data reception into a compact design. The Alice payloads are connected to the LCT by optical fibres allowing a flexible placement of the modules within the satellite bus. Collimators couple the light into free-space beams which are co-aligned and interfaced to the transmit telescope. In addition to the optical system design, this paper provides further information about the integration of the optical into the mechanical system, and the performed functional and qualification tests.
Quantum key distribution (QKD) enables secure communication even in presence of quantum computers. Satellite based systems enable worldwide key distribution and connection of terrestrial quantum networks. In future, QKD satellite constellations can be operated to service ground users that are connected using an optical ground station. These QKD ground stations are assumed to be deployed in two scenarios. One is the option as end-user ground station, in which the ground user is directly connected to the satellite via the ground station. The other option is the use as a provider ground station, in which the ground user is connected via an intermediary fiber line. The performance of the satellite to ground QKD link depends on, amongst other, the environmental and infrastructural impacts of the site where it is located. Unlike in astronomical sites, the QKD Optical Ground Station (OGS) are not positioned in selected optimal environment, especially considering atmospheric turbulence and extinction. The QKD OGS mainly has to cope with the given environment instead. Knowledge of the site’s meteorological and infrastructural environment is important to assess performance of a QKD OGS when deployed. This paper discusses the most relevant aspects of a QKD OGS site characterization. These are atmospheric turbulence, atmospheric extinction, and background light. As a concrete example, the DLR Optical Ground Station Oberpfaffenhofen nearby Munich is used. Existing data is summarized, reviewed and needs for further data acquisition defined.