****************************************************************************** dorismail 05-Feb-2020 17:13:06 Message No 1217 ****************************************************************************** Author: Ferrage Pascale Subject: DORIS 30th anniversary --_004_25CDFAC1A563514A82FC2E7BD9609F2FB1398B73TWMBXP03cnesnet_ boundary="_000_25CDFAC1A563514A82FC2E7BD9609F2FB1398B73TWMBXP03cnesnet_" --_000_25CDFAC1A563514A82FC2E7BD9609F2FB1398B73TWMBXP03cnesnet_ DORIS 30th Anniversary The DORIS system is 30 years old in February 2020, 30 years of continuous o= perations at the heart of the of altimetry mission performance for oceanogr= aphy and geodetic applications. The DORIS system (Doppler Orbitography and Radio positioning Integrated by = Satellite) was designed and developed in the early 1980s by CNES, IGN and G= RGS to determine satellite positions with high accuracy to support altimetr= y missions dedicated to ocean monitoring. DORIS was first embarked on the SPOT-2 satellite, which recorded the first = DORIS measurement on 3 February 1990. Since then, the system has operated c= ontinuously on 18 satellites, including the space imaging satellites SPOT2-= 3-4-5, Ple= iades1A-1B, altimetry missions for ocean observations such as Topex-Poseido= n= , Envisat, Jason-1/2/3, Hy-2A, Saral/AltiKa, Sentinel3-A/B, and also for hydrological m= onitoring and ice measurements with Envisat, Cryosat-2; Saral/AltiKa and Sentinel3= -A/B. This system allows the precise orbit determination of satellites embarking = DORIS receivers. It is based on Doppler shift measurements of radio-frequen= cy signals (400MHz & 2GHz) transmitted by a network of ground stations, use= d as reference points on the Earth's surface. About 60 DORIS stations unifo= rmly distributed around the world are hosted by more than 30 international = host agencies. Conversely, the DORIS system is able to locate ground positions with the sa= me accuracy. This duality of DORIS is associated to altimetric oceanography or ice missi= ons, to the study of the Earth's shape and movements, and a large number of= localization services. Thus, for the past 30 years: - DORIS contributes to monitoring changes in mean sea level, both = regionally and globally, using data from the TOPEX/Poseidon and Jason 1, 2,= & 3 missions. - Through the precise orbits provided for the Envisat, CryoSat-2,= Saral/AltiKa and Sentinel3-A/B missions, the DORIS system has participated= in monitoring the change in height of the Antarctic ice sheet over 25 year= s. - It contributes to the definition of the International Terrestria= l Reference Frame (ITRF) adopted in 2015 by the United Nations as a global = geodetic reference frame for sustainable development, the study of deformat= ions and movements of our planet. - It observes and analyses geophysical phenomena such as earthquak= es or periodic inflation and deflation events of volcanoes, tectonic plate = movements, local ground uplift or subsidence, etc. Since the beginning, the DORIS instruments (on board and on the ground), as= well as its monitoring system, have been in constant evolution, the stabil= ity of the system and its performances have not ceased to progress : The DO= RIS network is the most homogeneous, stable and durable geodetic network in= the world; in 30 years, the position in orbit has been reduced from 13 cm = to less than 1 cm; the DORIS-DIODE navigator on board the satellites calcul= ates the satellite's trajectory in real time with a radial accuracy of 2 to= 3 cm; the DORIS contribution to the ITRF has progressed in the same way wi= th new possible applications. Further progress is expected in the next decade with the 4th generation bea= con and the 3rd generation antenna, whose deployments started in 2019. Studies are underway for the development of a future miniaturized on-board = receiver coupling GNSS and DORIS signals. The DORIS system really has a bright future ahead of it and will contribute= to the success of many future missions that will carry it on board, such a= s Jason-CS/Sentinel-6 and HY-2C this year, then the SWOT (oceanography and hydrol= ogy) mission, the future Sentinel3 missions and, hopefully, many others to = come. Happy birthday DORIS and congratulations! More information on the International DORIS Service website and on the AVISO+ website. Please do not reply directly to this message, but send comments and suggestions to IDS.central.bureau@cls.fr --_004_25CDFAC1A563514A82FC2E7BD9609F2FB1398B73TWMBXP03cnesnet_--