Specular and Diffuse Components in Spherical Satellite Photometric Modeling

Abstract

Simulation efforts to inform investment decisions for future space sensors need a simple method to estimate the photometric behavior of satellites in a postulated future catalogue, generally for the purpose of emulating sensor detectability. Many simulations accomplish this by using the phase function of a diffuse sphere, at least for debris objects and sometimes for all object types. The present study examines other proposed phase functions from debris studies to determine if a competing (but simple) alternative phase function model can render improved fidelity. It also considers the earthshine contribution to satellite brightness and articulates conditions under which this phenomenon needs to be accounted for explicitly. The investigation demonstrated that a considerable improvement in predictive performance can be achieved by using simple models that allow a mixture of diffuse and specular components, although aspects of the results do force the observer to question these models’ ultimate adequacy. Guidance on the use of these models in simulations is also provided.