The International DORIS Service

The DORIS system was initially developed for precise orbit determination and precise positioning on the Earth. In continuation of the DORIS Pilot Experiment initiated in 1999, the International DORIS Service (IDS) officially started on July 1, 2003 as an IAG Service after an official acceptance from the IAG Executive Committee at the IUGG General Assembly in Sapporo, Japan. Following this decision, the IERS Directing board accepted the DORIS Service as a new IERS external service. Six satellites carrying DORIS receivers are currently in orbit, permanently observed by 56 well-distributed tracking stations. Among these, three satellites (Jason-1, ENVISAT and SPOT5) are equipped with the new generation of DORIS receivers and were launched between December 2001 and May 2002. The DORIS receivers on these three spacecraft include a navigation function, called DIODE. The permanent tracking network has been constantly improved and specific campaigns of observations have been conducted in Wettzell, Gads and in Antarctica. Recent DORIS performances for precise positioning were improved by this large increase in the satellite constellation, leading to almost 1 cm precision for weekly station coordinates. Significant improvements were also obtained in Polar Motion estimations, leading to 1.0-1.5 mas daily results. In 2003 and 2004, several steps were taken to improve the operations of the IDS, as well as its international cooperation, by organizing several specific analysis campaigns. The International DORIS Service has now started its scientific activity on a routine basis for the International Earth Rotation and Reference Systems Service (IERS) and the Global Geodetic Observing System (GGOS).