Keywords:DORIS, Space geodesy, ITRF, colocation
Doppler Orbitography and Radiopositioning Integrated by Satellite (DORIS) system is one of the four techniques that contributes to the International Terrestrial Reference Frame (ITRF). The technique was developed to support orbit determination on LEO satellites, most notably the suite of ocean radar altimeter satellites. The DORIS system consists of a global well-distributed set of ground beacons emitting on two frequencies (2 GHz and 401 MHz) and a satellite constellation consisting of an evolving suite of satellites that carry different generations of satellite receivers. Presently DORIS has colocations with other geodetic techniques at 47 out of 58 sites, many with GNSS. These include Badary, Greenbelt, Wettzell, and Yarragadee who host all four space geodesy techniques (DORIS, GNSS, SLR & VLBI), and Arequipa, Grasse, Kauai, Mt. Stromlo, Ny Alesund, Papeete, Jiufeng, and Syowa (Antarctica) who host three of the space geodetic techniques, including DORIS. The DORIS system became operational 30 years ago in February 1990, with its inauguration on the SPOT-2 satellite. Presently six satellites on-orbit carry a DORIS DGXX receiver (Cryosat-2, HY-2A, Jason-3, Saral, and Sentinel-3A and Sentinel-3B). A DGXX receiver can track up to seven ground beacons when they are in view of the orbiting satellite. This capability greatly increases the amount of data available for orbit determination and strengthens the DORIS contribution to the ITRF.
In this paper we provide a summary of the current status of the DORIS system, its science contributions, and its contributions to GGOS. We describe the evolution of the DORIS system including the improvements in the ground network, and summarize the products that are made possible by DORIS, including its contributions to the ITRF, and to the measurement of the change in Global Mean Sea Level.
In addition, we highlight the performance of select stations, such as the DORIS station in Syowa, Antarctica, including its contributions to science missions, and comparisons with other geophysical measurements.