Ground-based optical position measurements of space debris in low earth orbits

Kurzfassung

The increasing amount of space debris requires the satellite operators to handle a growing number of collision risk assessments in order to eventually perform collision avoidance manoeuvrers. For this scheme to work effective and reliable, the acquisition of highly accurate orbital position data of detected threatening space debris is necessary. The successful experimental demonstration of our earlier published concept on laser-based distance measurements of space debris in low earth orbits has proven this technique to be feasible for this task. Hereby a powerful short pulse laser system within a ground-based transceiver set-up is used to measure the time-of-flight of the back-scattered laser pulse from the space debris object. The time-of-flight information ultimately correlates with the object distance. A passive optical tracking unit equipped with a highly sensitive camera system is used for initial localisation and coarse determination of the debris position to guide the laser towards its target. In addition this unit provides the capability to determine accurate angular position information using the recorded star background. To experimentally investigate the potential contribution of a passive optical tracking unit for the debris position determination and to further develop our proposed concept, we have installed a passive-optical station at the public observatory on the Uhlandsh¨ohe in Stuttgart. We will discuss the requirements and the technical difficulties to set up such a system. Thereby we highlight the system parameters which influence the measurement accuracy as well as the debris size threshold. Furthermore we will give an outlook on our planned developments for the future.