Daniel O. Fulcoly (U.S. Air Force Academy), Katharine I. Kalamaroff (U.S. Air Force Academy), Francis K. Chun (U.S. Air Force Academy)
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Abstract:
When a satellite is either too small or too far away to visually resolve its physical details, other techniques must be used to characterize and describe them. One promising method is photometry – analyzing how the reflected light from a satellite varies as a function of time or phase angle. By plotting the range-normalized photometry versus the solar phase angle of the space object over several passes, we hope to see a characteristic shape that is indicative of a certain shape or attitude. The ultimate goal is be able to extract the exact shape and attitude of a known or unknown space object from its photometric curves. This is known as the inverse problem, and it is incredibly complex due to the large solution space containing all satellite orbits, shapes, materials, and attitudes. One way to enhance the analysis of such a problem is to get more information, and in our case this information will come from different telescope locations and multiple passes of the same satellite. Due to the complexity of the problem, this paper will be a case study limited to certain aspects of the analysis. The question we ask is “Given a certain scenario (orbit, engagement, shape, material, attitude, etc.) and central location (e.g. AEOS), what is the optimal arrangement of four deployable telescopes for determining the shape of the satellite? Certain shapes have a characteristic magnitude-phase angle distribution, especially in its lower boundary which is independent of satellite material and driven primarily by diffusive reflection. The optimum arrangement will be determined by how much of the phase angle coverage is met to determine the lower boundary of magnitude-phase angle distribution. We will discretize the area surrounding the central site and examine how much of the data is required to determine the satellite shape. Some constraints might be required, such as keeping one telescope in each quadrant or requiring there be a certain distance between satellites, to ensure that the optimal arrangement is not a trivial one (i.e. four telescopes at the same location).
Date of Conference: September 1-4. 2009
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