DORIS (geodesy)
Encyclopedia
Doppler Orbitography and Radiopositioning Integrated by Satellite (DORIS) is a French
satellite system used for the determination of satellite orbits (e.g. TOPEX/Poseidon
) and for positioning
.
). From this observation satellite orbits, ground positions, as well as other parameters can be derived.
). It is operated from Toulouse
, where a master beacon ensures the communication with the satellites.
base camp.
and Jason
. They are used to observe the ocean surface as well as currents or wave heights. DORIS contributes to their orbit accuracy of about 2 cm.
Other DORIS satellites are the ERS
, Envisat
and SPOT
satellites.
France
The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...
satellite system used for the determination of satellite orbits (e.g. TOPEX/Poseidon
TOPEX/Poseidon
Launched in 1992, TOPEX/Poseidon was a joint satellite mission between NASA, the U.S. space agency, and CNES, the French space agency, to map ocean surface topography. The first major oceanographic research vessel to sail into space, TOPEX/Poseidon helped revolutionize oceanography by proving the...
) and for positioning
Positioning
Positioning may refer to:* Positioning , creating an identity in the minds of a target market* Positioning , reader context* Positioning , a technology to approximate where a mobile phone temporarily resides...
.
Principle
A so called beacon is installed on the ground and emits a radio signal, which is received by the satellite. A frequency shift of the signal occurs that is caused by the movement of the satellite (Doppler effectDoppler effect
The Doppler effect , named after Austrian physicist Christian Doppler who proposed it in 1842 in Prague, is the change in frequency of a wave for an observer moving relative to the source of the wave. It is commonly heard when a vehicle sounding a siren or horn approaches, passes, and recedes from...
). From this observation satellite orbits, ground positions, as well as other parameters can be derived.
Organization
DORIS is a French system which was initiated and is maintained by the French Space Agency (CNESCNES
The is the French government space agency . Established under President Charles de Gaulle in 1961, its headquarters are located in central Paris and it is under the supervision of the French Ministries of Defence and Research...
). It is operated from Toulouse
Toulouse
Toulouse is a city in the Haute-Garonne department in southwestern FranceIt lies on the banks of the River Garonne, 590 km away from Paris and half-way between the Atlantic Ocean and the Mediterranean Sea...
, where a master beacon ensures the communication with the satellites.
Ground network
There are about 50-60 stations equally distributed over the earth and ensure a good coverage for orbit determination. For the installation of a beacon only electricity is required because the station only emits a signal but does not receive any information. Therefore it is possible to install beacons in remote areas such as the Mount EverestMount Everest
Mount Everest is the world's highest mountain, with a peak at above sea level. It is located in the Mahalangur section of the Himalayas. The international boundary runs across the precise summit point...
base camp.
Satellites
The best known satellites equipped with DORIS are the two altimetry satellites TOPEX/PoseidonTOPEX/Poseidon
Launched in 1992, TOPEX/Poseidon was a joint satellite mission between NASA, the U.S. space agency, and CNES, the French space agency, to map ocean surface topography. The first major oceanographic research vessel to sail into space, TOPEX/Poseidon helped revolutionize oceanography by proving the...
and Jason
Jason 1
Jason-1 is a satellite oceanography mission to monitor global ocean circulation, study the ties between the ocean and the atmosphere, improve global climate forecasts and predictions, and monitor events such as El Niño and ocean eddies....
. They are used to observe the ocean surface as well as currents or wave heights. DORIS contributes to their orbit accuracy of about 2 cm.
Other DORIS satellites are the ERS
European Remote-Sensing Satellite
European remote sensing satellite was the European Space Agency's first Earth-observing satellite. It was launched on July 17, 1991 into a Sun-synchronous polar orbit at a height of 782–785 km.-Instruments:...
, Envisat
Envisat
Envisat is an Earth-observing satellite. It was launched on 1 March 2002 aboard an Ariane 5 from the Guyana Space Centre in Kourou, French Guyana into a Sun synchronous polar orbit at an altitude of...
and SPOT
SPOT (satellites)
SPOT is a high-resolution, optical imaging Earth observation satellite system operating from space. It is run by Spot Image based in Toulouse, France...
satellites.