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A Mission for Geomagnetism and GPS Research
Satellite specifications:Satellitte total weight: 60.7 kgSatellite body: 72x45x34 cm. Mast: Coilable mast of 3 glassfibre longeronsTotal mast length: 8 mSections: 6 m to gondola + 2 m to topPower sources: Solar panels on 5 faces + NiCd batteryAverage power consumption: 37 wattsInstruments: 5 scientific instrumentsSystems: 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 DenmarkCommands: Uploaded from ground station and stored for time-tagged executionAttitude control: Autonomous magneto-torqer attitude regulationDetection of error conditions and transition to ”Power Save” mode: Autonomous
Radio communikation: Radio link: S-bånd (2.2 GHz) Transmitter and receiverData rate for download: 256 kbits/s for transmission to Ground StationData rate for upload: 4 kbits/s for up-load of commands or softwarePasses: 5-6 times/day
Initial conditions:Launched from: Vandenberg AFBDate and time: 23 Febuary, 1999, at 10:29:55 GMT, 11:29:55 Danish time. Ørsted separation: Lift-off + 6000.000 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: 0.015 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: -24.99 deg/orbit
Overhauser Scalar MagnetometerThe 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 Ørsted•DTU. (Photo: Leti)
Star Imager InstrumentThe 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 Ørsted•DTU section headed by John L. Jørgensen. (Photo: J.L. Jørgensen)
Compact Spherical Coil MagnetometerThe 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 Ørsted•DTU. PI for the instrument is Fritz Primdahl DSRI/DTU and Otto V. Nielsen, DTU. (Photo: Fritz Primdahl)
High-Energy Charged-Particle DetectorThe 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 ReceiverThe 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 2004. [email protected]