Satellite Determination of Earth Orientation with Emphasis on GPS

The ``classical'' satellite-based technique for determination of earth orientation (polar motion and changes in UT1/length of day) is laser ranging to the Lageos spacecraft. With the deployment of more GPS satellites and many high quality ground receivers, GPS-based approaches to EOP determination seem likely to achieve similar or better accuracies, with improved temporal resolution. Additional satellite methods make use of laser tracking to the Starlette or to the two Etalon spacecraft. The objective of the paper is to compare results obtained from these various techniques, using a common software package developed at ESOC for high precision orbit determination. The main emphasis is on experience gained during the IGS 1992 Campaign, one of the objectives of which was to assess the capability of GPS for fast, routine, high accuracy estimation of earth orientation