Space Debris Size Estimation Using Ellipsoidal Target Model

Space debris in LEO (Low Earth Orbit) are regularly tracked by ground-based radar to estimate its orbital parameters. Additional target characteristics such as the size of the debris, its attitude and stability are derived from the variation in Radar Cross Section (RCS) observed by the radar during the track. RCS gives an estimation of size of the target. Estimating the approximate size of the debris, its area to mass (a/m) ratio and its approximate shape and attitude stability is very important for characterizing the space debris and carrying out collision analysis. NASA's Equivalent Spherical Diameter (ESD) Size Estimation Model (SEM) provides the approximate diameter of the target assuming it as a sphere. But in reality all the space objects are not spherical in shape and the closest match is to consider it as an ellipsoid. This paper provides the simulation carried out to estimate the RCS of an ellipsoid with four different axial ratios and in all three scattering regions, namely, Rayleigh, MIE and Optical.