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France and Navigation Systems

To date France has not deployed a satellite navigation network, and plans to establish the Locstar system of two geostationary satellites for position-determination services were abandoned in July, 1991, when sufficient funds could not be raised (References 424). The system would have combined navigation aids with a data and message service but would have been limited to a restricted operational region between Europe and North Africa.

France is one of the four founding nations of the COSPAS-SARSAT search and rescue system and operates a LUT (Local User Terminal) at Toulouse. However, no COSPAS-SARSAT transponders are currently carried aboard French spacecraft. Since 1988 the ONES subsidiary CLS (Collecte Localisation Satellites) in conjunction with NASA and NOAA has operated a satellite-based location system under the Argos World Service network. Argos transponders attached to NOAA spacecraft can provide users equipped with a Platform Transmitter Terminal (PTT) position information accurate to about 350 m.

The French Starlette satellite (6 February 1975) was the first of a series of international geodetic satellites based on relatively simple spherical platforms embedded with laser reflectors and was followed by Lageos (US-1976), EGS (Japan-1986), Etalon (USSR-1989), and LAGEOS 2 (Italy-1992). The 47-kg Starlette is 26 cm in diameter, circles the Earth in an orbit of 800 km by 1,100 km at an inclination of 49.8 degrees, and carries 60 laser reflectors evenly distributed about its surface. On 26 September 1993 Starlette was joined by the French Stella satellite ofsimilar design. Stella accompanied the SPOT 3 satellite into a 795 km by 805 km, 98.7 degree-inclination orbit where it will enable geodetic measurements to be expanded into the polar regions. The Stella program is being managed by CNES and ONERA (Office National d'Etudes et de Recherches Aerospatiales).

During 1966-1975 France launched five other satellites with dedicated or auxiliary geodetic missions. Diapason (1966) was an active,19-kg satellite with 149.70 and 399.92 MHz transmitters to permit geodetic measurements based on doppler techniques and is no longer operational. Diademe 1 and Diademe 2 were launched one week apart in February, 1967, into elliptical orbits (currently, 550 km by 1,100 km and 600 km by 1,700 km, respectively) at an inclination of 40 degrees. In addition to dual-frequency transmitters like Diapason, the 22.6 kg Diademe spacecraft were also covered with numerous laser reflectors. Two other spacecraft also carried laser reflectors, Peole (1970) and Castor (1975), but both have since decayed.


424. CNES Annual Report 1990, CNES, 1991, p. 30-31.

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