Point Pairing Method Based on the Principle of Material Frame Indifference for the Characterization of Unknown Space Objects using Non-Resolved Photometry Data
AIR FORCE RESEARCH LAB KIRTLAND AFB NM SPACE VEHICLES DIRECTORATE
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The point pairing method in this paper is based on a set of simple physical truths for three-axis stabilized space objects in the geosynchronous orbit GEO. It defines a method for the calculation of pairs of observation conditions i.e. point pairs that have a special property for three-axis stabilized GEO object characterization. An observation condition is defined to be the geometry of illumination for the solar panel and the body of the satellite and the geometry of its observation by a sensor. The physical truths are due to observation conditions that are equivalent with respect to either the solar panel or body for a pair of points, which can be identified analytically. When the observation conditions are equivalent for the solar panel, the contribution to the GEO object brightness by the solar panel at that pair of points is identical. Then the difference between the pair of brightness values cancels the solar panel contribution unconditionally, and the remainder is only due to the body. Similarly, when the contribution of the body to the observed brightness is the same for the point pair, the difference between the two brightness values cancels the body contribution unconditionally and the remainder is only due to the solar panels. This enables separation of the observed brightness data into contributions by the solar panels and the body, which is fundamental to space-object characterization. This separation of the solar panel or body contributions is feasible in each waveband of observation. Thus point pairing is useful for the analysis of panchromatic as well as multispectral data. The desired conditions for point pairing occur routinely, typically within weeks of each other.