Accession Number : ADA289236

Title :   Satellite Surface Material Composition from Synthetic Spectra.

Descriptive Note : Master's thesis

Corporate Author : AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING

Personal Author(s) : Caudill, Eugene L.

PDF Url : ADA289236

Report Date : DEC 1994

Pagination or Media Count : 118

Abstract : The objective of this research was to determine if measurements from a Sagnac interferometer could provide reliable estimates of satellite material composition. The Sagnac interferometer yields a spatial interferogram that can sampled by a linear detector array. The interferogram is related to the spectrum of the source through a Fourier transform. Here, spectral reflectivities of nine common satellite materials were used to simulate the spectrum on obtains from an ideal Sagnac interferometer in the beam-train of a ground-based telescope whose mission is to view satellites. The signal-to-noise ratio of the spectrum was varied to simulate the effect of range variation between the sensor and the satellite. The simulated spectra consisted of a linear mixture of spectra from two of the nine materials. Three different architectures were developed and their performances compared. One of the three architectures consisted of nine artificial neural networks (ANNs), one for each material, and a linear estimator that estimated the satellite surface area attributable to each material. This method estimates the material composition by using a classifier to identify the materials contributing to the mixture, then eliminating unlikely contributors to the mixture before performing a constrained linear estimate. It is shown that due to high classification errors, the system using solely a linear estimator provides the estimate with the lowest errors.

Descriptors :   *SPACECRAFT, *COMPOSITE MATERIALS, *ARTIFICIAL INTELLIGENCE, *RECONNAISSANCE SATELLITES, *INTERFEROMETERS, FOURIER TRANSFORMATION, NEURAL NETS, SPACE SURVEILLANCE, TARGET RECOGNITION, THESES, OPTICAL IMAGES, RADAR, ILLUMINATION, LIGHT SOURCES, PHOTONS, PATTERN RECOGNITION, SPECTRUM ANALYSIS, COMPOSITION(PROPERTY), MICHELSON INTERFEROMETERS.

Subject Categories : Laminates and Composite Materials
      Cybernetics
      Optics
      Unmanned Spacecraft

Distribution Statement : APPROVED FOR PUBLIC RELEASE