Network performance analysis of laser-optical tracking for space situational awareness in the Lower Earth Orbit

Kurzfassung

In our paper, recent findings from a large system study on the performance of a global laser-ranging network are presented. Whereas the simulation methodology has been presented earlier at AMOS 2018, the current work shows a detailed performance analysis with respect to representative orbital element classes, available or conceivable station sites as well as realistic observability restrictions due to cloud coverage. For simulation configuration, orbital parameters of space objects in the Low Earth Orbit (LEO) have been statistically analyzed and clustered. A set of six orbit types with different semi-major axes and inclinations has been identified as representative for approximately 75% of all current LEO objects. For this selection, laser ranging networks of different sizes from 5 up to 50 laser ranging stations have been investigated. Simulations of laser-based measurements from each ranging network are analyzed in terms of orbit determination accuracy and covariance propagation. Whereas the former is reviewed during a 30-day period of target tracking, the latter is considered both in-between two different station transits with laser ranging as well as for a subsequent 5-day period without any further ranging measurements. For network performance characterization, the remaining position uncertainty of laser ranging data serves as a figure of merit. In particular, the results on network performance are mirrored against different configurations of the global station distribution under consideration of the respective orbital parameters. Moreover, network performance results are characterized with respect to downtimes due to weather restrictions. For this purpose, an 11-year month-specific statistics on the diurnal variations of cloud coverage and wind data (based on re-analysis of past weather) at each ranging location is employed. Requirements on network sizing and station distribution are discussed with respect to operational demands in space situational awareness. In sum, a networking approach in laser ranging constitutes a viable technology for the reduction of prevailing uncertainties in orbital data of LEO objects and can particularly be expected to serve as a prerequisite for future improvement for various SSA (Space Situational Awareness) use cases, e.g. conjunction analysis, collision risk assessment, collision avoidance, re-entry events, active debris removal, and proximity operations.