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Stereoscopic imaging determines space debris impact crater distribution and morphology

: Gulde, Max; Berger, Heiko; Putzar, Robin

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Aeronautics and Aerospace Open Access Journal : AAOAJ 1 (2017), No.4, Art. 00021, 5 pp.
Journal Article, Electronic Publication
Fraunhofer EMI ()
space debris; hypervelocity; impact; crater; stereovision; morphology; impact flux measurement

A two-step methodology based on imaging a spacecraft target surface in orbit is analyzed, which is capable of counting impact craters and determining their morphology. The methodology can be used to measure impact flux data and subsequently improve near-Earth particle environment models like MASTER and ORDEM. Craters are detected by a surface scan in a first step, and the morphology of selected craters is determined using stereoscopic images in a second step. To analyze the methodology, impact craters were modeled using Blender, visualized through MonoGame and the generated images analyzed with MATLAB using generic camera parameters. Optimum camera settings were derived for the particular scenario. For identification of the craters, the camera should be placed within 1.2 m of the surface. To determine the full, three-dimensional crater morphology, the camera needs to be placed much closer to the target surface. Both a rotation and a translation movement of the camera were investigated for recording the stereoscopic images. However, in view of the applicability of the method to map spacecraft surfaces, the translational movement is found to be more feasible to implement and less sensitive to inaccuracy during the positioning of the camera. In particular, a translation of the camera by about 0.4 times the target crater radius minimizes the sensitivity to misalignment of the camera. Improved particle environment models allow for more precise risk estimation for any future space mission, helping to save the lives of astronauts as well as preserving investments in space infrastructure.