An analysis of NASA laser ranging data from three stations located at Goddard Space Flight Center, Greenbelt, Maryland, Grand Turk Island, and Bermuda, respectively, was carried out in an attempt to measure the geometric earth tide. A 'quasi-geometric' method was employed that reduces the dependence on unmodelled satellite dynamics to a knowledge of only the radial position of the satellite by considering two-station simultaneous ranging at the precise time that the satellite passes through the plane defined by the two stations and the center of mass of the earth. Using this method, a good approximation to the theoretical Love number h2 was obtained from five passes over the Geos 3 calibration area when the geocentric distance to the satellite is adjusted by an amount, the same for each pass, which yields the least sum of the squares of the errors in the stations' geocentric distances and their angular separations. |