A Mission for Geomagnetism and GPS Research Satellite specifications: Satellitte total weight: 60.7 kg Satellite body: 72x45x34 cm. Mast: Coilable mast of 3 glassfibre longerons Total mast length: 8 m Sections: 6 m to gondola + 2 m to top Power sources: Solar panels on 5 faces + NiCd battery Average power consumption: 37 watts Instruments: 5 scientific instruments Systems: 13 different electronic systems Computer: Processor: 16 MHz 80C186 RAM memory: 16 Mbytes (holds over 12 hours of observational data) PROM memory: 0.5 Mbytes (re-programmerable by upload of software) ROM memory: holds permanent software for boot Software and operation: Data: Collected from all instruments and stored in RAM memory for download over Denmark Commands: Uploaded from ground station and stored for time-tagged execution Attitude control: Autonomous magneto-torqer attitude regulation Detection of error conditions and transition to ”Power Save” mode: Autonomous Radio communikation: Radio link: S-bånd (2.2 GHz) Transmitter and receiver Data rate for download: 256 kbits/s for transmission to Ground Station Data rate for upload: 4 kbits/s for up-load of commands or software Passes: 5-6 times/day Initial conditions: Launched from: Vandenberg AFB Date and time: 23 Febuary, 1999, at 10:29:55 GMT, 11:29:55 Danish time. Ørsted separation: Lift-off sec. Ascending node: 14:11 LT (drifting towards noon). Argument of perigee: 224 deg. Orbit parameters 23. February 2000 apogee: 865 km perigee: 649 km inclination:96.48 deg drift of orbit plane:0.76 deg/day local time increment:-0.90 min/day asc. node :08:43 LT semi major axis: 7128 km eccentricity: anomalistic period:99.82 min mean motion:14.43 perigee drift/day:-3.15 deg perigee drift/orbit:-0.22 deg nodal period:99.99 min longitude increment: deg/orbit Overhauser Scalar Magnetometer The Overhauser (OVH) scalar magnetometer measures the strength of the geomagnetic field with high precision. The instrument was constructed by Leti, France, and supplied by Centre National d’Etudes Spatiales (CNES). Danish PI for the instrument is Ib Laursen at ØrstedDTU. (Photo: Leti) Star Imager Instrument The Star Imager (SIM) comprises a video-camera, that records a section of the sky delimited by a baffle system. The position and strength of the stars are detected with high precision through sophisticated image processing and then compared to an on-board star catalogue. At match the precise SIM view direction is defined. The SIM instrument is mounted in the gondola on an optical bench shared with the CSC vector magnetometer. The Star Imager instrument was developed and built by the ØrstedDTU section headed by John L. Jørgensen. (Photo: J.L. Jørgensen) Compact Spherical Coil Magnetometer The Compact Spherical Coil (CSC) vector magnetometer measures the strength of the ambient magnetic field in three orthogonal directions. The instrument thus records the strength as well as the direction of the geomagnetic field at the satellite with high precision and great sensitivity. The instrument is boom-mounted to bring it to safe distance from possible disturbances generated in the satellite body. The instrumentet was developed and built at ØrstedDTU. PI for the instrument is Fritz Primdahl DSRI/DTU and Otto V. Nielsen, DTU. (Photo: Fritz Primdahl) High-Energy Charged-Particle Detector The Charged Particle Detector (CPD) instrument was developed and built by Peter Stauning, DMI, and Peter Davidsen, Terma. The instrumentet has 6 solid-state detectors with different depletion depths and shieldings. 4 of these detector units look upward along the mast while 2 detector units look horizontally to the side. The instrument is designed to detect the high-energy (penetrating) radiation in space, among other, composed of energetic electrons and protons. PI for the instrument is Peter Stauning, DMI. (Photo: P. Stauning) TurboRogue GPS Receiver The TurboRogue GPS precision receivers have been supplied by JPL/NASA. The instrument receives and analyses the signals from the available GPS-satellites. From analysis of the signal amplitude and phase during occultation, where the signal path from one of the GPS satellites to Ørsted descends to or rises from the horizon, it is possible to determine the temperature profile of the atmosphere, the content of water vapour in the lower regions and the electron densities in the upper atmospheric or ionospheric regions. Danish PI for the instrument is Per Høeg, DMI. (Photo: JPL/NASA) The Ørsted Satellite SIM sensor unit Peter Stauning. Danish Meteorological Institute. February