Date of Award

3-2004

Document Type

Thesis

Degree Name

Master of Science in Astronautical Engineering

Department

Department of Aeronautics and Astronautics

First Advisor

Richard G. Cobb, PhD

Abstract

Complete characterization of the space environment in support of the United States goal of space Situational Awareness is not currently achievable. When confronted with recent increases in the deployment and miniaturization of microsatellites by numerous nations, the questions of foreign space capabilities are magnified. This study sought to determine the feasibility of and experimentally demonstrate a microsatellite capability to autonomously loiter about and track a target satellite. Various methods of passive remote sensing were investigated to determine the best means of detecting and tracking a target in space. Microbolometer-based infrared sensors were identified as the best alternative. A representative system was constructed for demonstration in AFIT s SIMSAT laboratory. Software modeling results identified open-loop instability, and therefore the requirement for closed-loop control. A simple PD control algorithm served as the basis for control, and a pseudo-feed-forward term was added to improve results. The feed-forward term was derived from orbital dynamics as the rate at which the chase satellite traverses around an ellipse formed in the target s frame of reference. Reduction in pointing errors of up to 67% were found in simulations. Successful non-optimal tracking results were obtained in the laboratory with a hardware-in-the-loop model for both step and moving inputs.

AFIT Designator

AFIT-GA-ENY-04-M02

DTIC Accession Number

ADA425222

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