Ørsted (satellite)
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Ørsted is an Earth science satellite launched in 1999 to study the Earth's geomagnetic field. It is Denmark's first
satellite A satellite or an artificial satellite is an object, typically a spacecraft, placed into orbit around a celestial body. They have a variety of uses, including communication relay, weather forecasting, navigation ( GPS), broadcasting, scient ...
, named after
Hans Christian Ørsted Hans Christian Ørsted (; 14 August 1777 – 9 March 1851), sometimes Transliteration, transliterated as Oersted ( ), was a Danish chemist and physicist who discovered that electric currents create magnetic fields. This phenomenon is known as ...
(1777–1851), a Danish physicist and professor at the
University of Copenhagen The University of Copenhagen (, KU) is a public university, public research university in Copenhagen, Copenhagen, Denmark. Founded in 1479, the University of Copenhagen is the second-oldest university in Scandinavia, after Uppsala University. ...
, who discovered
electromagnetism In physics, electromagnetism is an interaction that occurs between particles with electric charge via electromagnetic fields. The electromagnetic force is one of the four fundamental forces of nature. It is the dominant force in the interacti ...
in 1820.


Objectives

The spacecraft's primary science objectives are to perform highly accurate and sensitive measurements of the geomagnetic field and to perform global monitoring of the high energy charged particle environment.


Instruments

The instrumentation consisted of two
magnetometer A magnetometer is a device that measures magnetic field or magnetic dipole moment. Different types of magnetometers measure the direction, strength, or relative change of a magnetic field at a particular location. A compass is one such device, ...
s ( proton precession and fluxgate), a star imager for attitude determination, a solid-state charged particle detector package, and a GPS receiver. The Science Instrument Team is responsible for the design of the instruments, while the Science Team is responsible for the science mission planning and international science participation. The science data obtained during the planned one-year mission will be used to derive an updated model of the geomagnetic field and its secular variation and to study the magnetospheric field-aligned currents and their relationship to ionospheric and solar wind conditions. The principal research topics are in two areas: 1° studies of the generation of the magnetic field in the fluid core and the magnetic and electrical properties of the solid Earth; and 2° studies of Earth's magnetic field as the controlling parameter of the
magnetosphere In astronomy and planetary science, a magnetosphere is a region of space surrounding an astronomical object in which charged particles are affected by that object's magnetic field. It is created by a celestial body with an active interior Dynamo ...
and of all the physical processes that take place in the Earth's plasma environment, including phenomena like
aurora An aurora ( aurorae or auroras), also commonly known as the northern lights (aurora borealis) or southern lights (aurora australis), is a natural light display in Earth's sky, predominantly observed in high-latitude regions (around the Arc ...
and magnetic storms. The primary scientific instruments on the Ørsted satellite are: * An Overhauser Effect Scalar 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 Compact Spherical Coil (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 A star tracker is an optical device that measures the positions of stars using photocells or a camera. As the positions of many stars have been measured by astronomers to a high degree of accuracy, a star tracker on a satellite or spacecraft may ...
developed by the
Danish Space Research Institute Danish Space Research Institute (DSRI) (Danish language, Danish: ''Dansk Rumforskningsinstitut'', short ''DRI'' or ''DRKI'') was the space agency of Denmark from 1966 to 2005. It was a Danish sector research institute formed in 1966 under the Danish ...
, to determine the orientation of the satellite. The other three instruments are located in the main body of the satellite: * The Charged Particle Detector, used to measure the
flux Flux describes any effect that appears to pass or travel (whether it actually moves or not) through a surface or substance. Flux is a concept in applied mathematics and vector calculus which has many applications in physics. For transport phe ...
of fast
electron The electron (, or in nuclear reactions) is a subatomic particle with a negative one elementary charge, elementary electric charge. It is a fundamental particle that comprises the ordinary matter that makes up the universe, along with up qua ...
s,
proton A proton is a stable subatomic particle, symbol , Hydron (chemistry), H+, or 1H+ with a positive electric charge of +1 ''e'' (elementary charge). Its mass is slightly less than the mass of a neutron and approximately times the mass of an e ...
s and
alpha particle Alpha particles, also called alpha rays or alpha radiation, consist of two protons and two neutrons bound together into a particle identical to a helium-4 nucleus. They are generally produced in the process of alpha decay but may also be produce ...
s around the satellite. * A Turbo-Rogue
GPS receiver A satellite navigation (satnav) device or GPS device is a device that uses satellites of the Global Positioning System (GPS) or similar global navigation satellite systems (GNSS). A satnav device can determine the user's geographic coordinat ...
, the main use of the receiver is to accurately determine the position of the satellite. Periodically this instrument may also be used to investigate the
atmospheric pressure Atmospheric pressure, also known as air pressure or barometric pressure (after the barometer), is the pressure within the atmosphere of Earth. The standard atmosphere (symbol: atm) is a unit of pressure defined as , which is equivalent to 1,013. ...
,
temperature Temperature is a physical quantity that quantitatively expresses the attribute of hotness or coldness. Temperature is measurement, measured with a thermometer. It reflects the average kinetic energy of the vibrating and colliding atoms making ...
, and
humidity Humidity is the concentration of water vapor present in the air. Water vapor, the gaseous state of water, is generally invisible to the human eye. Humidity indicates the likelihood for precipitation (meteorology), precipitation, dew, or fog t ...
beneath the satellite. To utilize the Ørsted science data return, the plan is to establish an internationally recognized research environment in the field of solar-terrestrial physics, a Solar-Terrestrial Physics Laboratory, comprising
magnetospheric In astronomy and planetary science, a magnetosphere is a region of space surrounding an astronomical object in which charged particles are affected by that object's magnetic field. It is created by a celestial body with an active interior Dynamo ...
,
ionospheric The ionosphere () is the ionized part of the upper atmosphere of Earth, from about to above sea level, a region that includes the thermosphere and parts of the mesosphere and exosphere. The ionosphere is ionized by solar radiation. It plays ...
, and
atmospheric physics Within the atmospheric sciences, atmospheric physics is the application of physics to the study of the atmosphere. Atmospheric physicists attempt to model Earth's atmosphere and the atmospheres of the other planets using fluid flow equations, rad ...
in combination with research in the magnetic field of the Earth. Correlative studies will be carried out using observations from existing monitoring stations in
Greenland Greenland is an autonomous territory in the Danish Realm, Kingdom of Denmark. It is by far the largest geographically of three constituent parts of the kingdom; the other two are metropolitan Denmark and the Faroe Islands. Citizens of Greenlan ...
and other polar regions.


Mission

The spacecraft was launched, on 23 February 1999 at 10:29:55 UTC, by a Delta II rocket, from the Vandenberg Air Force Base SLC-2W pad, as an auxiliary payload (primary payload was ARGOS and another auxiliary payload was SUNSAT; the auxiliary payload satellites were launched free of charge) into a near- Sun synchronous elliptical polar orbit, it had a
perigee An apsis (; ) is the farthest or nearest point in the orbit of a planetary body about its primary body. The line of apsides (also called apse line, or major axis of the orbit) is the line connecting the two extreme values. Apsides perta ...
of , an
apogee An apsis (; ) is the farthest or nearest point in the orbit of a planetary body about its primary body. The line of apsides (also called apse line, or major axis of the orbit) is the line connecting the two extreme values. Apsides perta ...
of , an
inclination Orbital inclination measures the tilt of an object's orbit around a celestial body. It is expressed as the angle between a reference plane and the orbital plane or axis of direction of the orbiting object. For a satellite orbiting the Eart ...
of 96.1, and an
orbital period The orbital period (also revolution period) is the amount of time a given astronomical object takes to complete one orbit around another object. In astronomy, it usually applies to planets or asteroids orbiting the Sun, moons orbiting planets ...
of 100.0 minutes, and nodal drift rate 0.76°/day. It is gravity-gradient stabilized, with its extendable boom aligned to and pointing away from the center of the Earth. Active attitude control is achieved using three-axis magnetic torquing coils. The data system features onboard monitoring and pre-processing. Data is stored in a 16 Mbyte on-board memory and downlinked in a packetized format when a ground station is in view. In 2010, Ørsted passed within 500 meters of debris from the
2009 satellite collision On February 10, 2009, two communications satellites—the active commercial Iridium 33 and the derelict Russian military Kosmos 2251—accidentally collided at a speed of and an altitude of above the Taymyr Peninsula in Siberia. It was the f ...
but suffered no damage. Based on data from the Ørsted satellite, researchers from the
Danish Space Research Institute Danish Space Research Institute (DSRI) (Danish language, Danish: ''Dansk Rumforskningsinstitut'', short ''DRI'' or ''DRKI'') was the space agency of Denmark from 1966 to 2005. It was a Danish sector research institute formed in 1966 under the Danish ...
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 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 ''Geophysical Research Letters'' is a biweekly peer-reviewed scientific journal of geoscience published by the American Geophysical Union that was established in 1974. The editor-in-chief iKristopher Karnauskas Aims and scope The journal aims for ...
,
Nature Nature is an inherent character or constitution, particularly of the Ecosphere (planetary), ecosphere or the universe as a whole. In this general sense nature refers to the Scientific law, laws, elements and phenomenon, phenomena of the physic ...
, and
Eos In ancient Greek mythology and Ancient Greek religion, religion, Eos (; Ionic Greek, Ionic and Homeric Greek ''Ēṓs'', Attic Greek, Attic ''Héōs'', "dawn", or ; Aeolic Greek, Aeolic ''Aúōs'', Doric Greek, Doric ''Āṓs'') is the go ...
. Ørsted was the first in a planned sequence of
microsatellites A microsatellite is a tract of repetitive DNA in which certain DNA motifs (ranging in length from one to six or more base pairs) are repeated, typically 5–50 times. Microsatellites occur at thousands of locations within an organism's genome. T ...
to be flown under the now discontinued Danish Small Satellite Programme. After more than twenty years in orbit, the Ørsted satellite is still operational (as of 2023), and continues to
downlink In a telecommunications network, a link is a communication channel that connects two or more devices for the purpose of data transmission. The link may be a dedicated physical link or a virtual circuit that uses one or more physical links or shar ...
accurate measurements of the
Earth's magnetic field Earth's magnetic field, also known as the geomagnetic field, is the magnetic field that extends from structure of Earth, Earth's interior out into space, where it interacts with the solar wind, a stream of charged particles emanating from ...
. Ørsted was constructed by a team of Danish space companies, of which CRI was prime contractor. CRI was acquired by
Terma A/S Terma A/S is a Danish defense and aerospace manufacturer for both civilian and military applications, and is owned by the Danish company Thrige Holding A/S. It is Denmark's largest company within the aerospace and the defense industry, employing ...
before Ørsted was launched, and the daily operations are run jointly by Terma A/S and the
Danish Meteorological Institute The Danish Meteorological Institute (DMI; ) is the official Danish meteorological institute, administrated by the Ministry of Climate, Energy and Utilities. It makes weather forecasts and observations for Denmark, Greenland, and the Faroe Is ...
.


See also

* Swarm (ESA mission) * Magsat


References

{{DEFAULTSORT:Orsted Science and technology in Denmark Geomagnetic satellites Spacecraft launched in 1999 Spacecraft launched by Delta II rockets First artificial satellites of a country