Validating the 1-cm orbit
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Determination of three dimensional orbit accuracy to the 1-cm level is a difficult problem for even today's most well-tracked satellites. Gravity fields that are extracted from low earth orbit (LEO) satellites operating near the 1-cm accuracy level provide a better understanding of Earth's systems. The importance of the 1-cm orbit requires a closer look at the means of orbit error validation for these LEO satellites. The focus of this analysis is on the orbits of the Gravity Recovery and Climate Experiment (GRACE) satellite pair. The main methods of validation used on GRACE are the analysis of SLR residuals and the generation of statistics of orbit overlaps. The derivation of a method based on the Guier plane analysis of range residuals is presented along with the results of its application. By combining the analysis of various methods for determining orbit accuracy, the processes for validating the 1-cm orbit are assessed. The results of the three methodologies applied to the SLR residuals for a dynamic orbit indicate that GRACE has radial orbit error of 1.5-cm root-mean-square (RMS) and a three dimensional orbit error of roughly 3-cm RMS. Therefore, it is highly unlikely that GRACE has achieved a 1-cm benchmark. The orbit overlaps study resulted in overly optimistic statistics and cannot be used as a measure of orbit accuracy.