Fraunhofer Institute for High Frequency Physics and Radar Techniques FHRMore than 2,700 inactive satellites, over 54,000 debris objects larger than 10 cm, and 1.2 million fragments between 1 and 10 cm: the growing volume of space debris poses a severe threat to space infrastructure. Collisions and further fragmentation endanger operational satellites and, with them, critical services in communication, navigation, and Earth observation. Within the STRATOLASER project, Fraunhofer FHR—working as part of a consortium—is investigating a novel approach to removing space debris. The objective is to develop a demonstrator of a laser ablation system mounted on a stratospheric balloon.
Removing Space Debris with Laser Technology
It may sound somewhat like science fiction: a high‑energy laser system equipped with relay mirrors mounted on a stratospheric balloon flying at an altitude of 30 km targets debris objects in orbit. The laser beam induces slight surface ablation on the object, generating a minimal recoil effect—similar to the thrust of a rocket. “This recoil alters the debris object’s trajectory and shifts it toward a lower orbit that extends deeper into Earth’s atmosphere. Increased atmospheric drag then causes it to descend progressively until it ultimately burns up,” explains Dr. Jens Klare, STRATOLASER project lead at Fraunhofer FHR.
By deploying the system on a stratospheric balloon, operations can take place above the dense layers of the atmosphere. Eliminating atmospheric attenuation and scattering of the laser beam allows the system to:
- drastically reduce the laser’s power requirements compared to ground‑based systems,
- significantly lower overall costs,
- improve maintainability and upgradeability, and
- offer greater versatility compared to space‑based solutions.
As part of the project, an initial experimental campaign will be conducted to demonstrate the proof of concept, achieve TRL 4, and establish the foundational technologies. Compared to space‑based systems, STRATOLASER aims to deliver lower costs, maintainability, enhanced versatility, and broader orbital access. In the current project phase, the consortium—comprising B2Space, HiLASE, CLPU, Sapienza University, and Fraunhofer FHR under the coordination of AICIA—is investigating two approaches: a UV laser mounted on the balloon, and a ground‑based infrared laser. The infrared laser is intended to target the balloon‑borne system, where it is converted into UV radiation that is then directed at the debris.
Initial Experiments with Two Stratospheric Balloons
The first experiments will be conducted using two stratospheric balloons. One balloon carries the laser system, which is tasked with tracking and hitting a debris target attached to the second balloon approximately 20 km away. “A major challenge will be hitting the debris. The balloon moves, and so does the target. The laser must also be capable of retargeting to strike the object multiple times for effective ablation. Additional challenges include the weight of the laser system and the energy required for operation and cooling,” notes Jens Klare.
In the next step, Fraunhofer FHR will use the capabilities of the TIRA space observation radar to identify suitable debris objects, determine their orbits, and transmit real‑time orbital data to the balloon‑borne laser system. The primary objective is to successfully hit the object at all. A subsequent mission analysis will examine whether the object’s orbit has measurably changed. Additional tests include laser scanning of space debris, focusing on signal return without reaching the ablation threshold due to power limitations.
Feasibility Study for On‑Board Radar Tracking
Fraunhofer FHR is also investigating whether a radar system of suitable size and power could be integrated into the stratospheric balloon. “We will obtain the exact parameters as the project progresses. Only once we know how much space, weight, and power the laser system requires can we determine what remains available for the radar. The key question is whether a compact, lightweight radar can be developed that can be carried by the balloon and determine initial orbital parameters of small space objects,” explains Jens Klare.
STRATOLASER within the EIC Pathfinder Challenge
STRATOLASER is part of the EIC Pathfinder Challenge on strengthening the sustainability and resilience of EU space infrastructure. A total of seven projects are funded under this initiative, with cross‑project collaboration planned. “These new opportunities for exchange are very exciting for us. It is an excellent chance for Fraunhofer FHR to contribute even more and to explore how we can further leverage TIRA and our expertise in tracking and cataloguing space objects,” concludes Jens Klare.
This project is funded by the European Union’s Horizon Europe research and innovation programme through the European Innovation Council (EIC) Pathfinder Challenge “Strengthening the sustainability and resilience of EU space infrastructure” under Grant Agreement No. 101223245.
