Direct evaluation of the earth's gravity anomaly field from orbital analysis of artificial earth satellites
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Date
1970-03
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Ohio State University. Division of Geodetic Science
Abstract
The equations of motion of an artificial earth satellite are derived in terms of gravity anomalies. In practice, an adjustment using these equations should give more correct values for the gravity anomalies. To check the adjustment equations derived, a set of 184 15° x 15° equal area mean gravity anomalies, together with the coordinates of some ground stations and Keplerian elements of certain satellites were assumed correct. Satellite orbits were generated, their positions being given by topocentric right ascension, declination, and range, assuming their motion to be affected only by the earth's gravitational potential. Errors were introduced into the assumed correct elements, new orbits were generated, and an adjustment was done to recover the introduced errors. Two solutions to recover the input anomaly errors were done. In the first solution, only the errors around perigee for geocentric satellite heights less than 8000km were properly recovered. An analysis of the second solution showed that assuming 10 mgals as the maximum acceptable difference between the input and recovered errors, 102 of the 184 anomaly errors were properly recovered. The rms value of the residuals from these 102 errors was ± 5.7 mgals. Taking the results in general together with the statistical tests made and the satisfactory recovery of the input errors of other elements besides anomalies, this method of directly evaluating gravity anomalies by analyzing satellite orbits can be regarded as feasible.
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Prepared for Air Force Cambridge Research Laboratories, Office of Aerospace Research, United States Air Force, Bedford, Massachusetts: Contract No. F19628-69-C-0127, Project No. 7600, Task No. 760002, 04