Laser Tracking and Removal of Space Debris

Since the first launch of the Sputnik satellite in 1957 several thousand satellites have been deployed in the low earth orbit (LEO), i.e. with an altitude of several 100 km to 2000 km. Since the atmospheric drag is strongly reduced at higher altitudes, objects with altitudes above 500 km remain in orbit for tens to hundreds of years. Hence many objects remain in space beyond their end of life. Additionally to satellites the population of smaller space debris particles is growing with an annual growth rate of approximately 5%. The available data base for space debris in the LEO contains more than 18000 objects with a size larger than 10 cm. Due to the high relative velocities larger than 8 km/s, even small space debris particles pose a major thread to satellites and space infrastructure such as the international space station (ISS). At the Institute of Technical Physics of the German Aerospace Center (DLR) we develop optical means to detect space debris and determine accurately the trajectory of debris particles. For the determination of space debris trajectories we use laser based ranging and tracking with pulsed infrared lasers. A high accuracy of the trajectories is of high importance in order to schedule avoidance maneuvers of active satellites. Finally, we will discuss the issue of space debris mitigation. Among several concepts, one concept is based on the application of high power laser pulses in order to modify the trajectory of smaller debris particles via laser ablation. The requirements and feasibility of this approach will be discussed.