Speaker
Description
In September 2018, a photographic survey of the outer surface of the Columbus module of the International Space Station (ISS) with emphasis on the forward facing areas was conducted to obtain information on the space debris and meteoroid environment at the ISS orbit. Video footage from the camera installed at the tip latching end effector (LEE) of the robotic arm (space station remote manipulator system, or SSRMS) comprises the primary data. This survey could be conducted thanks to the preparation effort of a team around DLR GSOC, University Oldenburg, DLR Institute of Space Systems, TU Braunschweig and Fraunhofer EMI, as well as the kind and substantial support from NASA and ESA. The main aim of the survey is to generate measurement data for particle environment models such as MASTER and ORDEM.
During analysis of the video data it became apparent that it is not sufficient to only identify and size craters in the videos, but that good position information is required for an accurate analysis of the data. The determination of the position of each individual video frame turned out to be non-trivial, since data from a variety of sources needed to be integrated: NASA SSRMS procedures, LEE geometry information, camera lens information, and Columbus module geometry information. The NASA SSRMS procedures used are incomplete in terms of the velocity of the camera, and only contain the start and end coordinates for each row. Therefore, the framewise camera displacement was extracted from the video data. Combining all this data allowed to localize each individual video frame.
In a second step, an algorithm was developed to automatically derive the size and position of the craters visible in the videos. This includes automatic processing of each individual video frame and tracking craters across multiple frames, thus combining all available data to obtain as precise as possible information on each individual crater. To size the craters in the video, a crater generated in a hypervelocity impact experiment at one of Fraunhofer EMI’s two-stage light-gas guns was performed, and the resulting crater investigated by the same method. The final algorithm was tested on a part of the ISS survey video.
The presentation will provide an overview on both algorithms (video frame localization, and crater localization with sizing), show the current status of the analysis of the dataset at Fraunhofer EMI, and give some insights into the problems encountered during the analyses. Since the analysis is still on-going, an outlook on the expected results will also be given.
