Abstract

To identify and characterize spacecraft in orbit, we employ ground-based optical telescopes with both imaging and nonimaging sensors. For objects that are unresolved or poorly-resolved due to their small size and/or long range from the observing station, nonimaging techniques are being explored for their potential to extract information for satellite identification and determination of status and function. The general task of obtaining shape, material composition, and orientation from nonimaging spectral data without any a priori knowledge of the object is impossible. This is due to the limited degrees of freedom in the data as compared to the degrees of freedom that define shape, function, and status. In fact, optical characteristics of individual satellites are influenced by a wide variety of parameters, such as surface scattering properties, material composition, shape, orientation, and illumination and viewing geometries.

© 2003 Optical Society of America