Ørsted (satellite)

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Oersted satellite model.jpg
Model of the Ørsted Satellite in the Tycho Brahe Planetarium
Mission typeEarth observation
OperatorDanish Meteorological Institute
COSPAR ID1999-008B
SATCAT no.25635
Mission duration20 years, 8 months and 19 days
Spacecraft properties
ManufacturerComputer Resources International
Launch mass61 kg (134 lb)
Dry mass50 kg (110 lb)
Dimensions34x45x72 cm (and an 8 m boom)
Power54.0 W (nominal)
Start of mission
Launch date23 February 1999, 10:29:55 (1999-02-23UTC10:29:55Z) UTC
RocketDelta II 7920-10 D267
Launch siteVandenberg SLC-2W
Orbital parameters
Reference systemGeocentric
RegimeLow Earth
(near–sun synchronous)
Semi-major axis7,111.179 km (4,418.682 mi)
Perigee altitude632.6 km (393.1 mi)
Apogee altitude833.4 km (517.9 mi)
Inclination96.4421 degrees
Period99.5 minutes
RAAN173.2395 degrees
Argument of perigee10.0389 degrees
Mean anomaly29.8678 degrees
Mean motion14.477406
Epoch14 December 2013, 14:18:37 UTC[1][2]

Ørsted is Denmark's first satellite, named after Hans Christian Ørsted (1777–1851), a Danish physicist and professor at the University of Copenhagen. It is in an almost-sun synchronous low Earth orbit.

After more than twenty years in orbit,[when?] the Ørsted satellite is still operational, and continues to downlink accurate measurements of the Earth's magnetic field. Ørsted was constructed by a team of Danish space companies, of which CRI was prime contractor. CRI was acquired by Terma A/S before Ørsted was launched, and the daily operations are run jointly by Terma A/S and the Danish Meteorological Institute.

In 2010, Ørsted passed within 500 meters of debris from the 2009 satellite collision but suffered no damage.[3]

Ørsted was the first in a planned sequence of microsatellites to be flown under the now discontinued Danish Small Satellite Programme.

Mission objectives[edit]

The main scientific objective of the spacecraft was to map the Earth's magnetic field and collect data to determine changes occurring in it.

Based on data from the Ørsted satellite, researchers from the Danish Space Research Institute concluded that the Earth's magnetic poles are moving, and that the speed with which they are moving has been increasing for the past few years.[when?] This apparent acceleration indicates that the Earth's magnetic field might be in the process of reversing, which could have serious consequences for land-based biological life.

The results have been published in several prominent scientific journals, and printed on the cover pages of Geophysical Research Letters,[4] Nature,[5] and Eos.[6]


The primary scientific instruments on the Ørsted satellite are:

  • An Overhauser magnetometer provides extremely accurate measurements of the strength of the geomagnetic field. The Overhauser magnetometer is situated at the end of an 8 meter long boom, in order to minimize disturbances from the satellite's electrical systems.
  • A CSC fluxgate vector magnetometer, used to measure the strength and direction of the geomagnetic field. The magnetometer is situated somewhat closer to the satellite body in the so-called "gondola", together with
  • A star tracker developed by the Danish Space Research Institute, to determine the orientation of the satellite.[7]

The other three instruments are located in the main body of the satellite:

See also[edit]


  1. ^ "CalSky - Orbit Elements of 99008B".
  2. ^ Peat, Chris (5 December 2013). "Orsted - Orbit". Heavens Above. Retrieved 6 December 2013.
  3. ^ terma.com Archived 2011-07-16 at the Wayback Machine
  4. ^ Purucker, M., Langlais, B., Olsen, N., Hulot, G. & Mandea, M.: The southern edge of cratonic North America: Evidence from new satellite magnetometer observations, Geophys.Res.Lett., 29(15), 8000, doi:10.1029/2001GL013645, 2002 [part of a special issue on results from the Ørsted satellite. Plate 3 from this paper is the cover of a special Ørsted issue on August 1, 2002 (Issue #15).]
  5. ^ Hulot, G., Eymin, C., Langlais, B., Mandea, M. & Olsen, N.: Small-scale structure of the geodynamo inferred from Oersted and Magsat satellite data, Nature, Volume 416, Issue 6881, pp. 620-623 (April 2002)
  6. ^ Neubert, T., Mandea, M., Hulot, G., von Frese, R., Primdahl, F., Jørgensen, J.L., Friis-Christensen, E., Stauning, P., Olsen, N. & Risbo, T.: Ørsted Satellite Captures High-Precision Geomagnetic Field Data, EOS, Vol. 82, No. 7, p. 81, 87, and 88, Feb. 13, 2001
  7. ^ Oxborrow, Carol Anne (13 January 2015). "Stellar navigation - DTU Space". Retrieved 16 July 2017.
  8. ^ Montenbruck, O; Garcia-Fernandez, M; Williams, J (2006). "Performance comparison of semicodeless GPS receivers for LEO satellites". GPS Solutions. 10 (4): 249–261. doi:10.1007/s10291-006-0025-9.