Magnetospheric research. European Space Agency satellite.

Typical orbit: 19393 x 37225 km, 19.2 deg inclinaton. Mass: 573 kg (1,263 lb).

• 1977 April 20 - ESA-Geos 1 - Launch Site: Cape Canaveral. Launch Complex: LC17B. Launch Vehicle: Delta. Mass: 573 kg (1,263 lb). Perigee: 2,939 km (1,826 mi). Apogee: 38,214 km (23,745 mi). Inclination: 26.60 deg. Period: 734.00 min.
  Spacecraft engaged in research and exploration of the upper atmosphere or outer space (US Cat B).

• 1978 July 14 - ESA-Geos 2 - Launch Site: Cape Canaveral. Launch Complex: LC17A. Launch Vehicle: Delta. Mass: 573 kg (1,263 lb). Perigee: 36,027 km (22,386 mi). Apogee: 36,049 km (22,399 mi). Inclination: 14.60 deg. Period: 1,449.00 min.
  Magnetospheric research. European Space Agency satellite. Launch time 1043 GMT. Reached initial operational position of 6 deg East on 26 Jul 1978. During the two years of its mission, it will be maintained in position between longitude 0 and 35 deg east in geosynchronous orbit. Positioned in geosynchronous orbit over the Atlantic Ocean at 36 deg E in 1978-1979 over the Atlantic Ocean 6-36 deg E in 1979-1981; over the Atlantic Ocean 24 deg E in 1981; over the Atlantic Ocean 33-37 deg E in 1981-1984 As of 3 September 2001 located at 177.77 deg W drifting at 3.212 deg W per day. As of 2007 Mar 9 located at 179.12E drifting at 3.212W degrees per day.