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The space surveyor

In 1666, Jean-Baptiste Colbert, adviser to Louis XIV, ordered the French Royal Science Academy to establish and update geographic maps. Defining a coherent system of measurement therefore became a royal priority, and the metre was designated as a basic unit.

Since then, the need to measure great distances with increasing accuracy has continued to grow. Space technologies now enable us to determine the coordinates of a point on Earth with centimetre accuracy.

The Doris system, designed and developed by CNES in collaboration with GRGS and IGN, has a dual purpose. It is used to determine the orbit of satellites equipped with Doris receivers with centimetre accuracy using a network of ground stations as reference points on Earth. Via this system, it is also now possible to precisely tie points to the International Terrestrial Reference Frame (ITRF).

This dual capability has enabled Doris to be used in numerous applications since 1992. The system is used in ocean or ice fields altimetry missions, studies of the shape and movements of Earth, as well as many location services.

(Doppler Orbitography and Radiopositioning Integrated by Satellite)
Initiators CNES in collaboration with the French survey and mapping agency IGN, and GRGS, the French space geodesy research centre
Origin need to improve the accuracy of orbit determination systems, to ensure the success of altimetry missions such as Topex/Poseidon
Status currently in operation , managed by SALP altimetry and precise positioning department at CNES
Participants CNES with IGN, GRGS, ESA and IDS (International Doris Service)
Objectives accurately measure the orbit of satellites and locate ground stations and provide autonomous onboard timing and navigation

passenger on SPOT 2 launched in 1990 (stopped in 2009)
payload of Topex/Poseidon launched in 1992 (stopped in 12006)
passenger on SPOT 3 launched in 1993 (stopped in 1996)
passenger on SPOT 4 launched in 1998
payload of Jason-1 launched in 2001
passenger on SPOT 5 launched in 2002
payload of Envisat launched in 2002
payload of Jason-2 launced in June 2008
payload and AOCS of Cryosat-2 planned for 2010
payload of French-Chinese HY2 altimetry mission scheduled in 2010
payload of Altika mission scheduled in 2010 (joint mission with India)
payload and AOCS equipment of the 2 Pleiades spacecrafts planned for 2010 and 2011
payload of Sentinel 3A scheduled in 2013

Last updated: December 2009