J. A. Marshall

TL;DR: An improved Earth geopotential model, complete to spherical harmonic degree and order 70, has been determined by combining the Joint Gravity Model 1 (JGM 1) coefficients, and their associated error covariance, with new information from SLR, DORIS, and GPS tracking of TOPEX/Poseidon, laser tracking of LAGEOS 1, LS1, LS2, and Stella as discussed by the authors.

TL;DR: The TOPEX/POSEIDON mission objective requires that the radial position of the spacecraft be determined with an accuracy better than 13 cm RMS (root mean square). This stringent requirement is an order of magnitude below the accuracy achieved for any altimeter mission prior to the definition of the TOPEX mission as mentioned in this paper.

TL;DR: The TOPEX/POSEIDON (T/P) pre-launch Joint Gravity Model-1 (JGM-1) and the post-launch JGM-2 Earth gravitational models have been developed to support precision orbit determination for T/P as mentioned in this paper.

TL;DR: In this article, the authors examined the spatial and temporal characteristics of the T/P radial orbit error, as assessed through the analysis of laser tracking residuals and orbit comparisons with independently generated trajectories.

TL;DR: GEM-T3 as discussed by the authors was developed from a combination of satellite tracking, satellite altimeter, and surface gravimetric data to estimate the Earth's gravity field at half wavelengths of 400 km and longer.