Making space traffic running more smoothly: Laser technology for satellite identification and debris nudging

Laser-optical innovations offer the potential to facilitate space traffic management and to support efforts for space debris mitigation and remediation. For these purposes, laser tracking and ranging is a crucial technology. Augmented by polarimetric capabilities, newly developed retro-reflector systems allow for encoding of an identification tag on board a satellite which can be read out remotely by a satellite laser ranging station on ground. Thus, SLR cannot only be used for precise orbit determination, but also avoid confusion in space due to unclaimed satellites. Orbit prediction of space debris objects by laser ranging implies significantly higher requirements in terms of laser power and receiver aperture than for cooperative satellites equipped with retroreflectors. Nevertheless, debris ranging pays off as found recently in the conceptual study LARAMOTIONS for the European Space Agency (ESA) showing that the number of erroneous collision alerts would greatly be reduced by more than one order of magnitude. Beyond that, the additional usage of high-power lasers opens up the possibility to exert photon pressure on space debris objects remotely from ground - making those uncooperative space objects accessible for collision avoidance maneuvers, in particular for potential collisions of debris objects among themselves. The related physical mechanisms of laser-based collision avoidance are explored together with a review of technological concepts and constraints for operational safety, complemented by an outlook on ESA's current activities in the field of laser momentum transfer.