Ørsted (satellite)

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Oersted satellite model.jpg
Model of the Ørsted Satellite in the Tycho Brahe Planetarium
Mission type Earth observation
Operator Danish Meteorological Institute
COSPAR ID 1999-008B
SATCAT no. 25635
Mission duration 18 years, 6 months and 27 days
Spacecraft properties
Manufacturer Computer Resources International
Launch mass 61 kg (134 lb)
Dry mass 50 kg (110 lb)
Dimensions 34x45x72 cm (and an 8 m boom)
Power 54.0 W (nominal)
Start of mission
Launch date 23 February 1999, 10:29:55 (1999-02-23UTC10:29:55Z) UTC
Rocket Delta II 7920-10 D267
Launch site Vandenberg SLC-2W
Contractor Boeing
Orbital parameters
Reference system Geocentric
Regime Low Earth
(near–sun synchronous)
Semi-major axis 7,111.179 km (4,418.682 mi)
Eccentricity 0.0141189
Perigee 632.6 km (393.1 mi)
Apogee 833.4 km (517.9 mi)
Inclination 96.4421 degrees
Period 99.5 minutes
RAAN 173.2395 degrees
Argument of perigee 10.0389 degrees
Mean anomaly 29.8678 degrees
Mean motion 14.477406
Epoch 14 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 seventeen years in orbit, 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 being run as a teamwork between 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 the changes occurring in the field.

Based on data from the Ørsted satellite, researchers from 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. This apparent acceleration indicates, that the poles of the Earth might be in the process of switching around, 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:

  1. Overhauser magnetometer provides extremely accurate measurements of the strength of the magnetic 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.
  2. CSC fluxgate vector magnetometer, used to measure the strength and direction of the magnetic field. The CSC magnetometer is situated somewhat closer to the satellite body in the so-called "gondola", together with the
  3. Star tracker developed by Denmark's national space institute to determine the orientation of the satellite.[7]

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

  1. Charged Particle Detector, used to measure the flux of fast electrons, protons and alpha particles around the satellite.
  2. BlackJack GPS Receiver, developed by the NASA Jet Propulsion Laboratory and used to accurately determine the satellite's position; can also be used to monitor the atmospheric pressure, temperature and humidity profile on the path between Ørsted and GPS satellites through atmospheric occultation.[8]
  3. Trimble TANS GPS Receiver, also used to determine the satellite's position as a backup to the BlackJack.

See also[edit]


  1. ^ http://www.calsky.com/observer/tle.cgi?satid=99008B&tdt=2456641.33063657
  2. ^ Peat, Chris (5 December 2013). "Orsted - Orbit". Heavens Above. Retrieved 6 December 2013. 
  3. ^ terma.com
  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. Springer-Verlag. 10 (4): 249–261. doi:10.1007/s10291-006-0025-9. Retrieved 2014-04-15.