DEMETER (Detection of Electro-Magnetic Emissions Transmitted from Earthquake Regions) was a French micro-satellite operated by CNES devoted to the investigation of the ionospheric disturbances due to seismic and volcanic activity.
It was launched on June 29, 2004, on a quasi Sun-synchronouscircular orbit with an inclination of about 98.23° and an altitude of about 710 km. The altitude was changed to about 660 km in December 2005.
Due to the specific orbit, DEMETER was always located either shortly before the local noon (10:30 local time) or local midnight (22:30 local time). The satellite performs 14 orbits per day and measures continuously between -65° and +65° of invariant latitude.[1]
Due to the limited capacity of the telemetry, there were two different modes of operation:
During the "Survey mode", averaged data were collected all around the Earth. The telemetry flow in this mode was reduced by the on-board data processing to 25 kbit/s.
During the "Burst mode", high-precision data were collected above the specific areas of interest, corresponding mostly to the seismic regions. The data bit rate in this mode was 1.7 Mbit/s.
Launches are separated by dots ( • ), payloads by commas ( , ), multiple names for the same satellite by slashes ( / ). Crewed flights are underlined. Launch failures are marked with the † sign. Payloads deployed from other spacecraft are (enclosed in parentheses).
