David E. Smith

TL;DR: The GEM-T1 model provides a simultaneous solution for a gravity model in spherical harmonics complete to degree and order 36, a subset of 66 ocean tidal coefficients for the long-wavelength components of 12 major tides, and 5-day averaged earth rotation and polar motion parameters for the 1980 period on as mentioned in this paper.

TL;DR: In this article, the low degree and order terms in the spherical harmonic model of the tidal potential were observed through the perturbations which are induced on near-earth satellite orbital motions.

TL;DR: In this paper, satellite laser ranging (SLR) data acquired during the period 1978-1988 were analyzed on the basis of the precise modeling of the orbit dynamics of Lageos, producing estimates of tectonic motion for 22 sites located on seven major plates.

TL;DR: Observations of the gravity field of Mars reveal a planet that has responded differently in its northern and southern hemispheres to major impacts and volcanic processes.

TL;DR: The current state of Mars polar research is assessed, the key questions that motivate the exploration of the polar regions are identified, the extent to which current missions will address these questions are discussed, and what additional capabilities and investigations may be required to address the issues that remain outstanding are speculated.