Space junk, also known as orbital debris, presents a growing challenge to the continued operation of satellites and the future of space exploration. This collection of defunct satellites, spent rocket stages, and fragments from collisions poses a collision risk to active spacecraft. Addressing this issue is important for maintaining a safe and sustainable space environment. Germany has emerged as a proactive player in developing solutions to this global problem, contributing through advanced research, dedicated removal concepts, and shaping international policy.
German Pioneering Research and Development
German institutions are pioneering research and technological innovations for understanding and mitigating space debris. The German Aerospace Center (DLR) funds research in space debris as part of its ‘Space Systems and Robotics’ program. Researchers at DLR have developed sophisticated models, such as the ESA MASTER model, to simulate the complex dynamics of debris clouds. These models are important for predicting potential collision events and planning avoidance maneuvers, and they assess the long-term evolution of the space debris environment, providing data for risk assessments.
Universities and research institutes across Germany develop technologies for debris tracking and characterization. DLR operates the TIRA radar system in Wachtberg, detecting debris down to two centimeters. The new GESTRA (German Experimental Space Surveillance and Tracking Radar) system, developed by Fraunhofer FHR for DLR, provides wide-range surveillance of debris in near-Earth space between 300 km and 3000 km. Fraunhofer EMI also developed a concept for ESA to record the speed, trajectory, and size of tiny debris.
DLR advances Satellite Laser Ranging (SLR) technology, developing mobile systems like miniSLR for accurate location determination of satellites and debris. This technology can measure the trajectory of other space objects, and DLR advocates equipping new satellites with reflectors for improved tracking. German engineers also investigate materials and robotic solutions for debris capture, including experimental laser ablation propulsion for debris removal. This research creates tools and knowledge for future active debris removal missions.
Dedicated Debris Removal Missions and Concepts
Germany has pursued projects and concepts for active space debris removal. The German Aerospace Center (DLR) contributed to ESA’s e.Deorbit mission concept, which explored technologies for capturing and deorbiting large, defunct satellites like Envisat. DLR’s involvement included rigid capture methods and robotic manipulation. This effort demonstrated the feasibility of actively removing large debris objects.
DLR also explored national concepts for in-orbit servicing and debris removal, such as the DEOS (Deutsche Orbitale Servicing Mission) concept. DEOS aimed to locate, approach, and capture a tumbling, non-cooperative satellite using a manipulator on a service satellite. DEOS also sought to demonstrate servicing tasks like refueling and module exchange. These studies provide insights into debris removal technologies, considering propulsion, navigation, and rendezvous techniques.
DLR’s Institute of Robotics and Mechatronics conducted ISS experiments, like the TumbleDock/ROAM project, where Astrobees robots simulate autonomously approaching and grasping tumbling objects. This work addresses interacting with uncontrolled debris. German companies also contribute to deorbiting solutions, with HPS developing the ADEO dragsail system. Reflex Aerospace plans to integrate ADEO into its satellites for end-of-life deorbiting by Lorentz drag, a fuel-free system. These projects showcase Germany’s commitment to developing and applying physical intervention methods to clean up hazardous objects.
Contributions to Global Space Governance and Standards
Germany plays a role in shaping international policy and efforts to mitigate space debris. The nation participates in the United Nations Committee on the Peaceful Uses of Outer Space (UN COPUOS), where it advocates for international guidelines for long-term sustainability of outer space activities. Germany contributed a report on its national implementation of UN COPUOS’s Long-Term Sustainability (LTS) Guidelines and supports initiatives like the Zero Debris Charter.
Germany, represented by the German Space Agency at DLR, is a member of the Inter-Agency Space Debris Coordination Committee (IADC). The German Space Agency chaired the IADC from April 2020 to October 2021, during which IADC documents, including the Space Debris Mitigation Guidelines, were updated. These guidelines provide international consensus on measures to prevent debris, like limiting debris released during operations and minimizing on-orbit break-ups.
The nation’s commitment extends to national regulations; DLR implements space debris mitigation requirements for its projects, consistent with UN, IADC, and European standards. Germany also takes a stance against creating new debris, pledging not to conduct destructive direct-ascent anti-satellite missile tests. This commitment was co-sponsored in a UN resolution, encouraging other nations to adopt responsible behaviors in space. Through these efforts, Germany contributes to establishing a global framework for a safer and more sustainable space environment.