Matthew Phelps, USSF SSC/SZG; Justin Fletcher, USSF SSC/SZG
Keywords: GEO, non-resolved characterization, space object, optical spectra, attitude, orientation, BRDF, helmholtz reciprocity, geometry
Abstract:
In this work, we derive a relation between the irradiance measured at the image plane of two conjugate sensor-target-source geometries. Such a relation is of interest in the application of ground-based optical sensors taking measurements of point-like geosynchronous space objects illuminated by the sun. The relation rests on a particular symmetry of the bidirectional reflectance distribution function (BRDF) known as Helmholtz reciprocity. Given the conjugate relation, we are able to directly relate the expected irradiance from a point reflector in one orientation to the expected irradiance in a conjugate orientation conditioned on a unique illumination geometry. Such a technique may enable one to match the optical spectra of a post-oriented geosynchronous space object to a registry of pre-oriented optical spectra at the conjugate geometry and thereby quantitatively infer the new orientation.
Date of Conference: September 19-22, 2023
Track: Satellite Characterization