Analysis of 04 years (2002-2005) of laser data on Starlette, Stella and LAGEOS-I/II satellites for stations coordinates and Earth Orientation Parameters (EOP)

Abstract

The present paper deals with the computation of Laser stations coordinates and Earth Orientation Parameters (EOP) based on measurements of low Earth orbit (LEO) satellites, namely Starlette (STA) and Stella (STL). The orbits of these satellites are less accurate than those of the LAGEOS satellites (usually used for an accurate calculation), because they are more affected by gravitational and non-gravitational forces. The objective is to achieve a good quality on the geodetic products by inter-satellite combination of Low and High satellites data. The orbit computation of the different satellites is performed by the GINS software (GRGS/France) and the laser data processing is carried out by the MATLO software (IGN, OCA/France), considering the use of gravity field model (Eigen_Grace-03s) of GRACE satellite, over a period of 04 years (between January 2002 and December 2005). The results in terms of time series are projected onto the reference frame ITRF2000 by the CATREF software (IGN/France), where the Helmert transformation parameters are obtained. Two solutions were compared: LA1 + LA2 (LL) and LA1 + LA2 + STL + STA (LLSS), in terms of quality time series of residual positions of stations, EOP and Geocentre variations. The results show that the data obtained from LEO satellites such as Starlette and Stella can be successfully used in the accurate determination of Laser geodetic products.