S-asteroid spectral interpreter (SASI): spectral analysis system for the Near-Earth Asteroid Rendezvous (NEAR) mission using a neural network preprocessor

摘要

Abstract: The surfaces of asteroids consist of mineral grains mixed on scales of 10-110's of micrometers where linear mixing rules for near-IR spectra do not apply. Further, the spectral properties of the mineral components are strong nonlinear functions of grain size and chemical composition. Detailed models of these nonlinear properties exist, but are not amenable to analytic inversion, requiring relatively inefficient iterative solutions to extract physical data from reflectance spectra. However, the NASA Near-Earth Asteroid Rendezvous mission soon to orbit the asteroid Eros requires near real time spectral analysis of near-IR spectral data for mission operations planning. The S- Asteroid Spectral Interpreter is a software system which includes a neural network which has been trained to invert the nonlinear physical model, and conventional gradient descent algorithm which refines the output of the neural network to arrive at a rapid analysis of input spectra. !7