Fraunhofer Institute of Optronics, System Technologies and Image Exploitation IOSB 
At present, more than 22,000 space debris objects in Low Earth Orbit (LEO) are tracked and catalogued. In the same orbital regime, there are estimated to be 150 million fragments of human-created junk, all less than 1 mm, travelling at around 7-8 km/s. This underscores the pressing need for effective solutions to address space situational awareness, tracking and imaging of space objects, space debris removal, and collision avoidance.
Several laser-based concepts for orbit modification have been proposed in recent years. One solution requires pulsed lasers with high energy (>10 kJ) in order to perform orbit modification through laser ablation. Alternative option is based on using high-power, continuous-wave lasers (>10 kW) for debris nudging by photon pressure. The latter provides a 3-4 orders of magnitude smaller effect than in the case of laser ablation, but when a greater number of laser stations is combined, it becomes a viable option.
We work on the possibility of photon-pressure-based orbit modification. When propagating in vacuum, energy delivery with laser beams is only limited by diffraction. In ground-to-space propagation on the other hand, the effectiveness of this method of collision avoidance is limited by atmospheric effects such as absorption, scattering and optical turbulence. The first two effects cannot be corrected, they can only be partially avoided by choosing laser wavelengths corresponding to atmospheric transmission windows, but detrimental beam broadening, deflections and intensity fluctuations which are all caused by atmospheric turbulence can in principle be mitigated to a certain extent by adaptive optics (AO) systems.
The project's key objectives are to design an AO system capable of compensating for the quickly changing wavefront distortions induced by atmospheric turbulence and telescope slew. The future system will utilize a laser guide star for sensing of the high-order aberrations and sunlight reflected from debris for low-order aberrations. The project will also involve the development of a demonstrator to validate the key AO system's functionalities in a controlled laboratory environment.
The focus lies in the development of the key components of a laser momentum transfer (LMT) AO system, which include: (1) a deformable mirror for pre-compensation of the high-power laser (Fraunhofer IOF), (2) a fast wavefront sensor for accurate measurements (Fraunhofer IOSB), and (3) a control system to efficiently compute and apply commands from the measurements to the deformable mirror (University of Applied Sciences Western Switzerland).