Evaluation of 14th-Order Harmonics in the Geopotential.
ROYAL AIRCRAFT ESTABLISHMENT FARNBOROUGH (ENGLAND)
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The Earths gravitational potential is now usually expressed in terms of a double series of tesseral harmonics with several hundred terms, up to order and degree at least 20. The harmonics of order 14 can be evaluated by analysing changes in satellite orbits which experience 14th-order resonance, when the track over the Earth repeats after 14 revolutions. This report describes the first evaluation of individual 14th-order coefficients in the geopotential from analysis of the variations in inclination and eccentricity of satellite orbits passing through 14th-order resonance under the action of air drag. Results from eleven satellites show values for eighteen normalized coefficients of harmonics of order 14 and degree 14, 15 ....22. These values provide a test of the accuracy of the 14th-order coefficients in comprehensive geoid models. Detailed comparisons with three recent models are made, showing good agreement on some coefficients and discrepances on others.
- Spacecraft Trajectories and Reentry