Active-optical debris detection: a means for highly accurate position determination of space debris orbits

In low Earth orbit (LEO), space debris is usually being tracked by radar facilities. However, optical systems can yield a complementary approach, especially towards high resolution measurements. A particular interesting approach is the method of active-optical observation using a pulsed laser source to derive the distance to the orbital object by a time-of-flight measurement. By combining it with the telescope pointing angles this yields the possibility of fast and accurate 3-D position measurements. Observations employing this technique can be a pathfinder technology for a subsequent laser-based removal of orbital debris in two aspects: First, any laser-based debris removal requires a precise knowledge of the objects position and trajectory before, during and after the application of the removal laser. The time-of-flight laser can be run alongside the removal laser to obtain this crucial information. Second, many technological and organizational challenges are similar for laser-based monitoring and removal: An accurate tracking of the object, the propagation of the laser beam towards the target, a practical laser safety concept and so on. An envisaged facility for laser-based debris removal can build upon the expertise gathered during the operation of laser-based monitoring. German Aerospace Center currently sets up a laser-based monitoring facility at the Orbital Debris Research Observatory in Stuttgart. In this contribution, the current state of the facility and first measurements are presented, as well as an outlook to the planned upgrades to the system