Milestones

 

After more than two decades of fully operational functioning, the DORIS space geodesy system has demonstrated its capabilities for orbitography and navigation of the satellites and also ground location. It plays a key role in the altimetric mission for oceanography providing in association with the Laser technique a 2 cm accuracy in the radial component of the orbit. DORIS and Laser are renewed as the nominal orbitographic system for the Jason mission (end of 2000).

DORIS also provides with Diode navigator on Spot 4 (1993), an orbit in real time within a few meters. It's a world first at this level of precision. Since the SPOT4 pilot experiment, other Diode Navigators have been flown on-board Envisat, Jason-2, Cryosat-2, Saral, Sentinel-3 … nearly every satellite carrying a DORIS receiver. Their accuracy was improved down to currently 2-3 centimeters RMS on Jason-2. This Real-Time orbit is inserted in the telemetry and in the OGDR products to allow Near Real-Time applications. 

Since 1994 and thanks to its more than fifty permanent beacon network, DORIS contributes to the IERS activities for the realization and maintenance of the ITRS (International Terrestrial Reference System). 3D positions and velocities of the reference sites at a cm and mm/yr accuracy lead to scientific studies (investigations) in the fields of global and regional tectonics. Two recent DORIS results appear very encouraging for the future. One concerns a seasonal effect of earth surface fluid mass redistribution (oceanic water, atmospheric masses, snow, ...) on the relative positions of the earth mass and earth figure centers. Another concerns vertical displacement of the crust monitored near tides-gages. This information is of major interest for the topic of sea level variations and correlation to the Global Change.

Such as the other space geodesy techniques GPS, VLBI, SLR, there is a strong demand among the scientific community to create an International DORIS Service, so called IDS. The CSTG, commission for international co-ordination of space techniques for geodesy of the International Association Geodesy (IAG) and the IERS directing board decided in July 1999 to initiate a DORIS Pilot Experiment. Its objective was to assess the need and feasibility of an International DORIS Service.
Since July,1 2003, the International DORIS Service has been officially started as an IAG Service after the decision of the IAG Executive Committtee at the IUGG General Assembly in Sapporo. New terms of reference were released. They describe the goals and organization of the IDS.

 

Milestones

 

dateevent
early 1980s Decision of the realisation of the DORIS system, jointly by the French space agency (Centre National d'Etude Spatial (CNES)), the French national mapping agency (Institut Géographique National (IGN)), and the French research group in the field of space geodesy (Groupe de Recherche de Géodésie Spatiale (IGN)).
1986 Start of the deployment of the DORIS ground network. 32 stations with ALCATEL antenna (type "A") installed before Spot-2 
1990 Spot-2 (Cnes) embarkes the first DORIS instrument, 1st generation with 1-channel receiver (6–month trial experiment, in use for more than 19 years). Goal of the mission: Earth observation. Objective for DORIS: decimeter level orbit accuracy.
1990 DORIS Day meeting (December 1990, Paris)
1992-1999 Densification of the network, expanded to 54 stations. Massive Alcatel antennas are progressively replaced the light and narrow Starec model (type "B").
1992 Topex/Poseidon (Nasa/Cnes) Goal: measure sea surface height. Objective reached by DORIS: 5-cm orbits quality in the radial component
1993 Spot-3 (Cnes) Goal: Earth observation
1994 First contribution  to ITRF (2 groups: IGN and LEGOS/GRGS)
1995 2nd generation of ground beacon
1998 Spot-4 (Cnes) with the first version of Diode software for real-time on-board orbit determination. Goal: Earth observation
1999 DORIS Pilot Experiment to assess the need and feasibility of an International DORIS Service. Setting up: Steering Committee, Data Centers, Analysis Centers, Central Bureau, website, mailing lists
2000-2009 Major renovation effort of the network. Objective: 1 cm over 10 years in terms of stability of the DORIS antenna reference point. 
2001 Jason-1 (Cnes/Nasa) with the first DORIS receiver of the 2nd generation with 2 channels. Goal: measure sea surface height
2002 Envisat (Esa). Goal: observe Earth's atmosphere and surface
2002 Spot-5 (Cnes). Goal: Earth observation
2003 Official start of IDS as an IAG Service, on July 1st (IGS: 1994; ILRS: 1998; IVS: 1999)
Objective: to provide a service to support geodetic and geophysical research activities through DORIS data and derived products.
2003 First IDS Governing Board meeting (November 2003, Arles, France)
2003? 3rd generation beacons with the ability to emit on shifted frequency
2004 3rd Master Beacon at Hartebeesthoek (South Africa)
2005 DORIS Integrity Team set up to monitor permanently the DORIS signal transmitted in space, control its characteristics, investigate non nominal situations, take corrective actions if needed.
2005 Contribution to ITRF2005 (4 groups: IGN/JPL, LEGOS/CLS, INASAN, NASA/GSFC
2007? 1st Time beacon driven by a Hmaser installed in Yellowknife
2007 STPSat-1: Citris (Scintillation and Tomography receiver in space) developped by the NRL (Naval Research Laboratory) uses the transmissions of the DORIS beacons.
2008 Jason-2 (Cnes/Nasa/Eumetsat/Noaa) with the first DORIS receiver of the 3rd generation (DGXX) with 7 channels. Goal: measure sea surface height
2008 DORIS/Jason-2 data are provided by CNES in legacy doris format and in RINEX/DORIS (first mission)
2008 First Analysis Working Group meeting
2009 Start of the Combination Centre
2009 Contribution to ITRF2008 (7 groups: IGN/JPL, CNES/CLS, INASAN , NASA/GSFC , ESOC, GOP, Geosciences Australia)
2009 First IDS Activity Report (2006-2008)
2009 4th Master Beacon at Papeete
2010-today Modernization of the network. The DORIS network achieves 90% coverage (for satellites orbiting at 800 km altitude) and provides a reliable service with a network availability maintained over 85% of operating stations since 2012 thanks to the joint effort of CNES, IGN and all agencies hosting the stations.
2010 Cryosat-2 (ESA) Goal: polar observation
2010 Initialization of the routine combination by the Combination Center
2011 HY-2A (China Academy of Space Technology) Goal: observe the ocean dynamics
2013 Saral/Altika (Isro/CNES) Goal: observe the oceans
2014 Deployment of Starec ground antennae with consolidated manufacturing process (type "C")
2014 IDS webservice: dynamic plot tools of time series + network viewer
2014-2015 Contribution to ITRF2014 (6 groups: IGN/JPL, CNES/CLS, INASAN , NASA/GSFC , ESOC, GOP)
2016 Jason-3 (Cnes/Nasa/Eumetsat/Noaa) with the 1st DGXX-S instrument. Goal: measure sea surface height
2016 DORIS/Jason-3 data are provided by CNES in RINEX/DORIS only (first mission)
2016 Sentinel-3A (ESA - Copernicus program) Goal: deliver routine operational services to policy-makers and marine and land service users
2016 First IDS Newsletter
2018 Sentinel-3B (ESA - Copernicus program) Goal: deliver routine operational services to policy-makers and marine and land service users
2018 First IDS retreat. IDS is 15!
2019? Deployement of the 4th generation beacons