Statistical analysis of the ESA optical space debris surveys

In the framework of ESA's space debris research program optical measurements to search for space debris in high‐altitude orbits are performed with the ESA 1‐m telescope on Tenerife. Observations have been acquired during more than 500 nights during the past 6 years. Most of the data are ‘statistical’ in the sense that no catalogue of orbital data for individual objects is produced but only a list of ‘detections’ including rough orbital information and a visual magnitude for each of these detections. Moreover due to the narrow field of view of the telescope the optical surveys provide only snapshot‐like samples of the space debris environment. There is no simple relation between the observed detection rates and the number of objects. In this paper we compare the ESA optical survey data from the year 2006 with simulated observations for different model populations, including the MASTER‐2005 population. The simulations are performed with a software suite that links the ESA PROOF tool to our tools and takes into account the detailed observation scenarios and the details of the telescope and the camera system. A simulation using a geostationary (GEO) population with homogeneously distributed orbital elements is performed to analyze potential selection biases in the orbital element space of the observation scenarios. Of particular interest is the question if the observation scenarios may result in ‘artificial clusters’ in the observed distribution of the orbital planes. The simulation results for a GEO catalogue population are directly comparable with correlated detections and objects from the 2006 survey. The main results in this case are the percentage of detected objects with respect to the used catalogue and the coverage in the orbital element space. Finally the comparison of the observations with the results from simulations using the MASTER population represents an independent validation of the MASTER‐2005 model. Using the results from the three mentioned simulations, we derive an estimate for the number of debris objects seen by the ESA 2006 surveys.