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Equator-S [MPE]

Equator-S is an element of the International Solar-Terrestrial Physics (ISTP) program. Spacecraft design, manufacturing and testing were provided by the Max-Planck-Institut für Extraterrestrische Physik (MPE). The project was financially supported by DARA (Deutsche Agentur fur Raumfahrt Angelegenheiten).

The Equator-S objectives are to provide high-resolution plasma, magnetic, and electric field measurements in several regions not adequately covered by the existing ISTP missions, namely the low-latitude dayside magnetopause and its boundary layer, the equatorial ring current region, and the near-earth equatorial plasma sheet. These regions play key roles for our understanding of the global perspective of solar-terrestrial relations as well as the detailed plasmaphysical processes.

The orbit is near-equatorial, with 500 km perigee altitude and 11 Re geocentric apogee distance. The payload consists of seven scientific instruments provided by international groups to study the solar wind and charged particles trapped in the earth's magnetosphere. For reasons of cost and schedule, these instruments are largely derived from engineering or spare units from other ISTP missions. Innovative sub-systems for solar power and orbit measurement are tested on Equator-S for the benefit of future spacecraft designs. Furthermore, some technological experiments have been added that exploit the hard radiation environment of the Equator-S orbit or make use of its orbital features. The rapid spacecraft spin rate (60 rpm) allows unprecedented high temporal resolution of the measurements.

Nation: Germany
Type / Application: Science, magnetosphere
Operator: DARA
Contractors: Max-Planck-Institut fur Extraterrestrische Physik (MPE)
Configuration: Spin stabilized
Propulsion: Star-13A
Power: Solar cells, batteries
Mass: 250 kg
Orbit: 564 km × 67070 km, 3.75°
Satellite COSPAR Date LS Launch Vehicle Remarks
Equator-S 1997-075B 02.12.1997 Ko ELA-2 Ariane-44P H10-3 with JCSat 5


  • Max-Planck-Institut für extraterrestrische Physik: Equator-S
  • NSSDC Master Catalog: Equator-S
Further ISTP missions: