Advances in SLR orbit determination

Abstract

Since LAGEOS II was launched from the space shuttle in October 1992, the Global Tracking Network has provided an extensive set of Satellite Laser Ranging data which supplement the 20 year record of LAGEOS I. The contrasting behavior of small unmodeled along-track accelerations in the orbits of each satellite can be used to help explain the sources of these perturbations. LAGEOS II's 52 degree inclination provides gravity and tidal sensitivity to improve on the advances from LAGEOS I in a shorter time, as LAGEOS II's nodal precession period is about one half that of LAGEOS I's three year period. The combination of data from the two LAGEOS satellites, together with observations from other geodetic satellites, such as ETALON I and II, allows better definition of polar motion and length-of-day, which can now be resolved at sub-daily intervals during periods of concentrated tracking. The geometry added by LAGEOS II has also been found to improve station positioning accuracy for studies of regional deformation in the vicinity of the laser observatories. The improved SLR global reference frame can now be used to accurately define orbit and station positions from a variety of space and conventional geodetic methods.