Measuring impact craters on the ISS Columbus Module

This paper presents the plan and first results of a photographic survey of the outer surface of the Columbus module with emphasis on the forward facing areas. This is to perform a status check of the Columbus meteoroid and debris protection system (MDPS) and to obtain information on the space debris and meteoroid environment of the ISS (International Space Station). The expected different impact crater count between zenith and forward facing panels will allow a distinction between man-made space debris and natural meteoroids. The majority of impacts is expected on the forward side of the cylindrical area. The survey is performed using image acquisition hardware available onboard the ISS. Different acquisition options are discussed, with the SSRMS (Canadarm2) tip LEE (Latching End Effector, i.e. the tip of the arm) camera being the most realistic option, but also the one with the lowest expected resolution. The predicted crater size distribution is calculated using ESA's MASTER model, and the proposed survey is compared with historical mission data that were used to validate the MASTER population in the past. The first part of the survey was performed on 5 September 2018, the second part between 21 and 23 September 2018, and some initial results are presented. The data acquired will be analyzed to yield size and position information of all craters identifiable from the video stream. The main aim of the survey is to generate measurement data for particle environment models (MASTER and ORDEM). This data will allow for a quantitative assessment of the particle impact risk for the entire ISS with an unprecedented accuracy. Also, it will allow to re-assess the validity of the impact risk assessments done for the Columbus module in the past. Since the Columbus module surface will be covered partially by the commercial platform ""Bartolomeo"" and the ColKa communication terminal soon, there is a limited time slot for the actual performance of this study.