The use of short arc orbital constraints in the adjustment of geodetic satellite data
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Date
1969-01
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Publisher
Ohio State University. Division of Geodetic Science
Abstract
In this report many different aspects of the orbital constraint adjustment are discussed, comparing it in many ways with the corresponding geometric mode adjustment. The difficulty in modeling the orbit is the biggest drawback to the orbital mode adjustment, and this is described at some length. It is shown that for any given set of data, the orbital constraint adjustment will produce a solution that is as good as or better than the corresponding geometric mode adjustment. A description of the flow of a particular orbital constraint adjustment computer program is presented. The discussion of this specific program is used to illustrate several general computational and programming considerations. A series of experiments involving BC-4 photographic plates is described. The path of the satellite appears as a trail of small dot-like images on these plates, and the possibility of imposing an orbital constraint on these trails is discussed. Results are presented of the adjustment of these images in the short arc orbital mode, and the results of several different configurations of geometric mode adjustments are given for the sake of comparison. These results indicate that for short enough arcs the modeling error may be suppressed and the orbital mode adjustment yields an unbiased solution which is almost the same as that obtained by the geometric method, However, the expected strengthening of the solution due to the imposition of the orbital constraint does not seem to be strong enough to show up in these experiments. Moreover, the short arc orbital constraint adjustment appears to be especially prone to a severe accumulation of numerical error, due to the presense of ill-conditioned matrices.
Description
Prepared for National Aeronautics and Space Administration, Washington, D.C.: Contract No. NGR 36-008-093, OSURF Project No. 2514