The micro-satellite DEMETER
Résumé
The scientific objectives of DEMETER are related to the investigation of the ionospheric perturbations due to the seismic activity, and to the global study of the Earth electromagnetic environment. The scientific payload is composed of several sensors: three electric and three magnetic sensors (6 components of the EM field to investigate from DC up to 3.5 MHz), a Langmuir probe, an ion spectrometer, and, an energetic particle analyzer. They are associated with two special items: a large onboard memory (8 Gbits) in order to record data all around the Earth, and a high bit rate telemetry in X band (18 Mb/s). There are 2 modes of operation: a survey mode to record low bit rate data and a burst mode to record high bit rate data above seismic regions. In the survey mode the telemetry is of the order of 950 Mb/day, and in burst mode, it is larger than 1 Gb/orbit. The launch by CNES (French National Space Agency) will be at the end of 2003 and the duration of the mission is 2 years. DEMETER is a micro-satellite (110 kg) with a low-altitude (<800 km) and a nearly polar orbit.