Radiometric considerations for the detection of space debris with an optical sensor in LEO as a secondary goal of the AsteroidFinder mission

The German Aerospace Center (DLR) is pursuing a national space program based on a Standard Satellite Bus (SSB) belonging to the compact class. After a review process, AsteroidFinder was selected to be the first mission featuring a DLR SSB. The mission is presently in its Phase-B development stage, with a launch planned for 2013. In addition to its primary goal of discovering Inner Earth Objects (IEOs), a secondary goal of the AsteroidFinder mission is to demonstrate the feasibility of the detection and statistical classification of cm-sized space debris with a satellite-based optical instrument. The increasing risk for astronauts and spacecraft caused by the growing number of space debris requires a deeper involvement in space debris investigations. Ground-based measurements of the particle population supported by either radar or optical instruments have become worldwide a standard method of research. However, the space-based detection is still in its infancy. As the debris' signal is not disturbed by the atmosphere in space, this method shall help to observe particularly small particles. In this paper the mission and payload will be introduced and the first simulations on the optical detectability of small objects will be discussed. The results of the radiometric considerations, which include the interaction of the debris size, the debris velocity and the particle's distance to the camera, indicate that it is well possible to detect cm-sized objects with AsteroidFinder. Thus, information on statistics of the orbital debris population can be obtained.