Cluster mission
Encyclopedia
Cluster II is a space mission of the European Space Agency
, with NASA
participation, to study the Earth
's magnetosphere
over the course of an entire solar cycle. The mission is composed of four identical spacecraft flying in a tetrahedral
formation. A replacement for the original Cluster spacecraft which were lost in a launch failure in 1996, the four Cluster II spacecraft were successfully launched in pairs in July and August 2000 onboard two Soyuz-Fregat rocket
s from Baikonur
. In February 2011, Cluster II celebrated 10 years of successful scientific operations in space. The mission has been extended until December 2012. China National Space Administration
/ESA Double Star mission
operated alongside Cluster II from 2003 to 2007.
interacts with the magnetosphere
and affects near-Earth space and its atmosphere
, including aurorae
. The satellites are named Rumba, Salsa, Samba and Tango but are more commonly called Cluster 1, Cluster 2, Cluster 3 and Cluster 4 or even C1, C2, C3 and C4.
The spacecraft are cylindrical (290 x 130 cm, see online 3D model) and are spin-stabilized at 15 rotations per minute
. After launch, their solar cell
s provided 224 watt
s power for instruments and communications. The four spacecraft maneuver into various tetrahedral formations to study the magnetospheric structure and boundaries. The inter-spacecraft distances can be varied from around 17 to 10,000 kilometers (km). The propellant
for the maneuvers makes up approximately half of the spacecraft's launch weight.
The highly elliptical
orbit
s of the spacecraft reach a perigee
of around 4 RE (Earth radii, where 1 RE = 6371 km) and an apogee of 19.6 RE. Each orbit takes approximately 57 hour
s to complete. The European Space Operations Centre
(ESOC) acquires telemetry
and distributes to the online data centers the science data from the spacecraft.
(SOHO). Though the original Cluster spacecraft were completed in 1995, the explosion of the Ariane 5
rocket carrying the satellites in 1996 delayed the mission by four years while the instruments were rebuilt.
On July 16, 2000, a Soyuz-Fregat rocket from the Baikonur Cosmodrome
launched two of the replacement Cluster II spacecraft, (Salsa and Samba) into a parking orbit from where they maneuvered under their own power into a 19,000 by 119,000 kilometer orbit
with a period of 57 hours. Three weeks later on August 9, 2000 another Soyuz-Fregat rocket lifted the remaining two spacecraft (Rumba and Tango) into similar orbits. Spacecraft 1, Rumba, is also known as the Phoenix spacecraft, since it is largely built from spare parts left over after the failure of the original mission. After commissioning of the payload, the first scientific measurements were made on February 1, 2001.
The ESA ran a competition to name the satellites, which attracted participants from many countries. Ray Cotton from the United Kingdom won with the names Rumba, Tango, Salsa and Samba. Ray's town of residence, Bristol
, was awarded with scale models of the satellites in recognition of the naming and connection with the satellites.
Originally planned to last until the end of 2003, the mission has been extended several times. The first extension took the mission from 2004 until 2005, and the second from 2005 to June 2009. The mission has now been extended until end 2012.
comprising the magnetosphere cannot presently be accessed using remote sensing techniques, satellites must be used to measure it in-situ. Four spacecraft allow scientists make the 3D, time-resolved measurements needed to create a realistic picture of the complex plasma interactions occurring between regions of the magnetosphere and between the magnetosphere and the solar wind.
Each satellite carries a scientific payload of 11 instruments designed to study the small-scale plasma structures in space and time in the key plasma regions: solar wind, bow shock
, magnetopause
, polar cusps, magnetotail, plasmapause boundary layer and over the polar caps and the auroral zones.
launched the Double Star
satellites, TC-1 and TC-2, that worked together with Cluster to make coordinated measurements mostly within the magnetosphere
. TC-1 stopped operating on 14 October 2007. Here are three scientific highlights where TC-1 played a crucial role
1. Space is Fizzy
Ion density holes were discovered near the Earth's bow shock
that can play a role in bow shock formation. The bow shock is a critical region of space where the constant stream of solar material, the solar wind, is decelerated from supersonic speed to subsonic speed due to the internal magnetic field of the Earth.
Full story: http://sci.esa.int/jump.cfm?oid=39559
Echo of this story on CNN:
http://www.cnn.com/2006/TECH/space/06/20/space.bubbles/index.html
2. Inner magnetosphere and energetic particles
Chorus Emissions Found Further Away From Earth During High Geomagnetic Activity.
Chorus are waves naturally generated in space close to the magnetic equator, within the Earth's magnetic bubble called magnetosphere. These waves play an important role in the creation of relativistic electrons and their precipitation from the Earth's radiation belts. These so called killer electrons can damage solar panels and electronic equipments of satellites and represent a hazard to astronauts. Therefore, information on their location with respect to the geomagnetic activity is of crucial importance to be able to forecast their impact.
Chorus sound file: http://sci.esa.int/science-e/www/object/doc.cfm?fobjectid=38339
3. Magnetotail dynamics
Cluster and Double Star Reveal the Extent of Neutral Sheet Oscillations.
For the first time, neutral sheet oscillations observed simultaneously at a distance of tens of thousands of kilometres are reported, thanks to observations by 5 satellites of the Cluster and the Double Star Program missions. This observational first provides further constraint to model this large-scale phenomenon in the magnetotail.
Full story: http://sci.esa.int/jump.cfm?oid=38999
"The TC-1 satellite has demonstrated the mutual benefit of, and has fostered, scientific cooperation in space research between China and Europe. We expect even more results when the final archive of high resolution data will be made available to the worldwide scientific community", underlines Philippe Escoubet, Double Star and Cluster mission manager of the European Space Agency.
European Space Agency
The European Space Agency , established in 1975, is an intergovernmental organisation dedicated to the exploration of space, currently with 18 member states...
, with NASA
NASA
The National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...
participation, to study the Earth
Earth
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...
's magnetosphere
Magnetosphere
A magnetosphere is formed when a stream of charged particles, such as the solar wind, interacts with and is deflected by the intrinsic magnetic field of a planet or similar body. Earth is surrounded by a magnetosphere, as are the other planets with intrinsic magnetic fields: Mercury, Jupiter,...
over the course of an entire solar cycle. The mission is composed of four identical spacecraft flying in a tetrahedral
Tetrahedron
In geometry, a tetrahedron is a polyhedron composed of four triangular faces, three of which meet at each vertex. A regular tetrahedron is one in which the four triangles are regular, or "equilateral", and is one of the Platonic solids...
formation. A replacement for the original Cluster spacecraft which were lost in a launch failure in 1996, the four Cluster II spacecraft were successfully launched in pairs in July and August 2000 onboard two Soyuz-Fregat rocket
Rocket
A rocket is a missile, spacecraft, aircraft or other vehicle which obtains thrust from a rocket engine. In all rockets, the exhaust is formed entirely from propellants carried within the rocket before use. Rocket engines work by action and reaction...
s from Baikonur
Baikonur
Baikonur , formerly known as Leninsk, is a city in Kyzylorda Province of Kazakhstan, rented and administered by the Russian Federation. It was constructed to service the Baikonur Cosmodrome and was officially renamed Baikonur by Russian president Boris Yeltsin on December 20, 1995.The shape of the...
. In February 2011, Cluster II celebrated 10 years of successful scientific operations in space. The mission has been extended until December 2012. China National Space Administration
China National Space Administration
The China National Space Administration is the national space agency of the People's Republic of China responsible for the national space program. It is responsible for planning and development of space activities...
/ESA Double Star mission
Double Star Mission
Double Star is a joint satellite based space mission by the China National Space Administration and the European Space Agency . It is the first space mission launched by China to investigate Earth's magnetosphere. It consists of two satellites: an Equatorial satellite and Polar satellite...
operated alongside Cluster II from 2003 to 2007.
Mission overview
The four identical Cluster II satellites study the impact of the Sun's activity on the Earth's space environment by flying in formation around Earth. For the first time in space history, this mission is able to collect three-dimensional information on how the solar windSolar wind
The solar wind is a stream of charged particles ejected from the upper atmosphere of the Sun. It mostly consists of electrons and protons with energies usually between 1.5 and 10 keV. The stream of particles varies in temperature and speed over time...
interacts with the magnetosphere
Magnetosphere
A magnetosphere is formed when a stream of charged particles, such as the solar wind, interacts with and is deflected by the intrinsic magnetic field of a planet or similar body. Earth is surrounded by a magnetosphere, as are the other planets with intrinsic magnetic fields: Mercury, Jupiter,...
and affects near-Earth space and its atmosphere
Atmosphere
An atmosphere is a layer of gases that may surround a material body of sufficient mass, and that is held in place by the gravity of the body. An atmosphere may be retained for a longer duration, if the gravity is high and the atmosphere's temperature is low...
, including aurorae
Aurora (astronomy)
An aurora is a natural light display in the sky particularly in the high latitude regions, caused by the collision of energetic charged particles with atoms in the high altitude atmosphere...
. The satellites are named Rumba, Salsa, Samba and Tango but are more commonly called Cluster 1, Cluster 2, Cluster 3 and Cluster 4 or even C1, C2, C3 and C4.
The spacecraft are cylindrical (290 x 130 cm, see online 3D model) and are spin-stabilized at 15 rotations per minute
Minute
A minute is a unit of measurement of time or of angle. The minute is a unit of time equal to 1/60th of an hour or 60 seconds. In the UTC time scale, a minute on rare occasions has 59 or 61 seconds; see leap second. The minute is not an SI unit; however, it is accepted for use with SI units...
. After launch, their solar cell
Solar cell
A solar cell is a solid state electrical device that converts the energy of light directly into electricity by the photovoltaic effect....
s provided 224 watt
Watt
The watt is a derived unit of power in the International System of Units , named after the Scottish engineer James Watt . The unit, defined as one joule per second, measures the rate of energy conversion.-Definition:...
s power for instruments and communications. The four spacecraft maneuver into various tetrahedral formations to study the magnetospheric structure and boundaries. The inter-spacecraft distances can be varied from around 17 to 10,000 kilometers (km). The propellant
Propellant
A propellant is a material that produces pressurized gas that:* can be directed through a nozzle, thereby producing thrust ;...
for the maneuvers makes up approximately half of the spacecraft's launch weight.
The highly elliptical
Ellipse
In geometry, an ellipse is a plane curve that results from the intersection of a cone by a plane in a way that produces a closed curve. Circles are special cases of ellipses, obtained when the cutting plane is orthogonal to the cone's axis...
orbit
Orbit
In physics, an orbit is the gravitationally curved path of an object around a point in space, for example the orbit of a planet around the center of a star system, such as the Solar System...
s of the spacecraft reach a perigee
Perigee
Perigee is the point at which an object makes its closest approach to the Earth.. Often the term is used in a broader sense to define the point in an orbit where the orbiting body is closest to the body it orbits. The opposite is the apogee, the farthest or highest point.The Greek prefix "peri"...
of around 4 RE (Earth radii, where 1 RE = 6371 km) and an apogee of 19.6 RE. Each orbit takes approximately 57 hour
Hour
The hour is a unit of measurement of time. In modern usage, an hour comprises 60 minutes, or 3,600 seconds...
s to complete. The European Space Operations Centre
European Space Operations Centre
The European Space Operations Centre is responsible for controlling ESA satellites and space probes. The centre is located in Darmstadt, Germany. It is Mission Control for most of the space projects of the ESA. Since its creation in 1967, the centre has operated 60 European space missions...
(ESOC) acquires telemetry
Telemetry
Telemetry is a technology that allows measurements to be made at a distance, usually via radio wave transmission and reception of the information. The word is derived from Greek roots: tele = remote, and metron = measure...
and distributes to the online data centers the science data from the spacecraft.
History
The Cluster mission was proposed to ESA in 1982 and approved in 1986, along with the Solar and Heliospheric ObservatorySolar and Heliospheric Observatory
The Solar and Heliospheric Observatory is a spacecraft built by a European industrial consortium led by Matra Marconi Space that was launched on a Lockheed Martin Atlas IIAS launch vehicle on December 2, 1995 to study the Sun, and has discovered over 2100 comets. It began normal operations in May...
(SOHO). Though the original Cluster spacecraft were completed in 1995, the explosion of the Ariane 5
Ariane 5
Ariane 5 is, as a part of Ariane rocket family, an expendable launch system used to deliver payloads into geostationary transfer orbit or low Earth orbit . Ariane 5 rockets are manufactured under the authority of the European Space Agency and the Centre National d'Etudes Spatiales...
rocket carrying the satellites in 1996 delayed the mission by four years while the instruments were rebuilt.
On July 16, 2000, a Soyuz-Fregat rocket from the Baikonur Cosmodrome
Baikonur Cosmodrome
The Baikonur Cosmodrome , also called Tyuratam, is the world's first and largest operational space launch facility. It is located in the desert steppe of Kazakhstan, about east of the Aral Sea, north of the Syr Darya river, near Tyuratam railway station, at 90 meters above sea level...
launched two of the replacement Cluster II spacecraft, (Salsa and Samba) into a parking orbit from where they maneuvered under their own power into a 19,000 by 119,000 kilometer orbit
Orbit
In physics, an orbit is the gravitationally curved path of an object around a point in space, for example the orbit of a planet around the center of a star system, such as the Solar System...
with a period of 57 hours. Three weeks later on August 9, 2000 another Soyuz-Fregat rocket lifted the remaining two spacecraft (Rumba and Tango) into similar orbits. Spacecraft 1, Rumba, is also known as the Phoenix spacecraft, since it is largely built from spare parts left over after the failure of the original mission. After commissioning of the payload, the first scientific measurements were made on February 1, 2001.
The ESA ran a competition to name the satellites, which attracted participants from many countries. Ray Cotton from the United Kingdom won with the names Rumba, Tango, Salsa and Samba. Ray's town of residence, Bristol
Bristol
Bristol is a city, unitary authority area and ceremonial county in South West England, with an estimated population of 433,100 for the unitary authority in 2009, and a surrounding Larger Urban Zone with an estimated 1,070,000 residents in 2007...
, was awarded with scale models of the satellites in recognition of the naming and connection with the satellites.
Originally planned to last until the end of 2003, the mission has been extended several times. The first extension took the mission from 2004 until 2005, and the second from 2005 to June 2009. The mission has now been extended until end 2012.
Scientific objectives
Previous single and two-spacecraft missions were not capable of providing the data required to accurately study the boundaries of the magnetosphere. Because the plasmaPlasma (physics)
In physics and chemistry, plasma is a state of matter similar to gas in which a certain portion of the particles are ionized. Heating a gas may ionize its molecules or atoms , thus turning it into a plasma, which contains charged particles: positive ions and negative electrons or ions...
comprising the magnetosphere cannot presently be accessed using remote sensing techniques, satellites must be used to measure it in-situ. Four spacecraft allow scientists make the 3D, time-resolved measurements needed to create a realistic picture of the complex plasma interactions occurring between regions of the magnetosphere and between the magnetosphere and the solar wind.
Each satellite carries a scientific payload of 11 instruments designed to study the small-scale plasma structures in space and time in the key plasma regions: solar wind, bow shock
Bow shock
A bow shock is the area between a magnetosphere and an ambient medium. For stars, this is typically the boundary between their stellar wind and the interstellar medium....
, magnetopause
Magnetopause
The magnetopause is the abrupt boundary between a magnetosphere and the surrounding plasma. For planetary science, the magnetopause is the boundary between the planet’s magnetic field and the solar wind. The location of the magnetopause is determined by the balance between the pressure of the...
, polar cusps, magnetotail, plasmapause boundary layer and over the polar caps and the auroral zones.
- The bow shockBow shockA bow shock is the area between a magnetosphere and an ambient medium. For stars, this is typically the boundary between their stellar wind and the interstellar medium....
is the region in space between the Earth and the sunSunThe Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields...
where the solar wind decelerates from super- to sub-sonic before being deflected around the Earth. In traversing this region, the spacecraft make measurements which help characterize processes occurring at the bow shock, such as the origin of hot flow anomalies and the transmission of electromagneticElectromagnetic radiationElectromagnetic radiation is a form of energy that exhibits wave-like behavior as it travels through space...
waves through the bow shock and the magnetosheathMagnetosheathThe magnetosheath is the region of space between the magnetopause and the bow shock of a planet's magnetosphere. The regularly organized magnetic field generated by the planet becomes weak and irregular in the magnetosheath due to interaction with the incoming solar wind, and is incapable of fully...
from the solar wind.
- Behind the bow shock is the thin plasma layer separating the Earth and solar wind magnetic fields known as the magnetopauseMagnetopauseThe magnetopause is the abrupt boundary between a magnetosphere and the surrounding plasma. For planetary science, the magnetopause is the boundary between the planet’s magnetic field and the solar wind. The location of the magnetopause is determined by the balance between the pressure of the...
. This boundary moves continuously due to the constant variation in solar wind pressure. Since the plasma and magnetic pressures within the solar wind and the magnetosphere, respectively, should be in equilibrium, the magnetosphere should be an impenetrable boundary. However, plasma has been observed crossing the magnetopause into the magnetosphere from the solar wind. Cluster's four-point measurements make it possible to track the motion of the magnetopause as well as elucidate the mechanism for plasma penetration from the solar wind.
- In two regions, one in the northern hemisphere and the other in the south, the magnetic field of the Earth is perpendicular rather than tangential to the magnetopause. These polar cusps allow solar wind particles, consisting of ions and electrons, to flow into the magnetosphere. Cluster records the particle distributions, which allow the turbulent regions at the exterior cusps to be characterized.
- The regions of the Earth's magnetic field that are stretched by the solar wind away from the sun are known collectively as the magnetotail. Two lobes that reach past the Moon in length form the outer magnetotail while the central plasma sheet forms the inner magnetotail, which is highly active. Cluster monitors particles from the ionosphereIonosphereThe ionosphere is a part of the upper atmosphere, comprising portions of the mesosphere, thermosphere and exosphere, distinguished because it is ionized by solar radiation. It plays an important part in atmospheric electricity and forms the inner edge of the magnetosphere...
and the solar wind as they pass through the magnetotail lobes. In the central plasma sheet, Cluster determines the origins of ion beams and disruptions to the magnetic field-aligned currents caused by substorms.
- The precipitation of charged particles in the atmosphere creates a ring of light emission around the magnetic pole known as the auroral zone. Cluster measures the time variations of transient particle flows in the region.
Double Star mission with China
In 2003 and 2004, the China National Space AdministrationChina National Space Administration
The China National Space Administration is the national space agency of the People's Republic of China responsible for the national space program. It is responsible for planning and development of space activities...
launched the Double Star
Double Star Mission
Double Star is a joint satellite based space mission by the China National Space Administration and the European Space Agency . It is the first space mission launched by China to investigate Earth's magnetosphere. It consists of two satellites: an Equatorial satellite and Polar satellite...
satellites, TC-1 and TC-2, that worked together with Cluster to make coordinated measurements mostly within the magnetosphere
Magnetosphere
A magnetosphere is formed when a stream of charged particles, such as the solar wind, interacts with and is deflected by the intrinsic magnetic field of a planet or similar body. Earth is surrounded by a magnetosphere, as are the other planets with intrinsic magnetic fields: Mercury, Jupiter,...
. TC-1 stopped operating on 14 October 2007. Here are three scientific highlights where TC-1 played a crucial role
1. Space is Fizzy
Ion density holes were discovered near the Earth's bow shock
Bow shock
A bow shock is the area between a magnetosphere and an ambient medium. For stars, this is typically the boundary between their stellar wind and the interstellar medium....
that can play a role in bow shock formation. The bow shock is a critical region of space where the constant stream of solar material, the solar wind, is decelerated from supersonic speed to subsonic speed due to the internal magnetic field of the Earth.
Full story: http://sci.esa.int/jump.cfm?oid=39559
Echo of this story on CNN:
http://www.cnn.com/2006/TECH/space/06/20/space.bubbles/index.html
2. Inner magnetosphere and energetic particles
Chorus Emissions Found Further Away From Earth During High Geomagnetic Activity.
Chorus are waves naturally generated in space close to the magnetic equator, within the Earth's magnetic bubble called magnetosphere. These waves play an important role in the creation of relativistic electrons and their precipitation from the Earth's radiation belts. These so called killer electrons can damage solar panels and electronic equipments of satellites and represent a hazard to astronauts. Therefore, information on their location with respect to the geomagnetic activity is of crucial importance to be able to forecast their impact.
Chorus sound file: http://sci.esa.int/science-e/www/object/doc.cfm?fobjectid=38339
3. Magnetotail dynamics
Cluster and Double Star Reveal the Extent of Neutral Sheet Oscillations.
For the first time, neutral sheet oscillations observed simultaneously at a distance of tens of thousands of kilometres are reported, thanks to observations by 5 satellites of the Cluster and the Double Star Program missions. This observational first provides further constraint to model this large-scale phenomenon in the magnetotail.
Full story: http://sci.esa.int/jump.cfm?oid=38999
"The TC-1 satellite has demonstrated the mutual benefit of, and has fostered, scientific cooperation in space research between China and Europe. We expect even more results when the final archive of high resolution data will be made available to the worldwide scientific community", underlines Philippe Escoubet, Double Star and Cluster mission manager of the European Space Agency.
2011
- September 6 -Ultra fast substorm auroras explained
- August 31 - 40 year old Mariner 5 solar wind problem finds answer
- July 5–10 - Aurora explorer: the Cluster mission exhibit at the Royal Society summer science exhibition 2011
- July 4 - Cluster observes jet braking and plasma heating
- June 30 - 'Dirty hack' restores Cluster mission from near loss
- March 21 - How vital is a planet's magnetic field? New debate rises
- February 5 - Cluster encounters a natural particle accelerator
- January 7 - ESA spacecraft model magnetic boundaries
2010
- November 22 - ESA extends the Cluster mission until December 2014
- October 4 - Cluster helps disentangle turbulence in the solar wind
- September 1 - 10 years of success for Cluster quartet
- July 26 - Cluster makes crucial step in understanding space weather
- July 16 - Cluster's decade of discovery
- July 8 - Announcement of opportunity for Cluster guest investigators
- June 3 - The Cluster archive: more than 1000 users
- April 24 - High-speed plasma jets: origin uncovered
- March 11 - Shocking recipe for 'killer electrons'
- January 20 - Multiple rifts in Earth's magnetic shield
2009
- October 7 - ESA extends the Cluster mission until December 2012
- July 16 - Cluster shows how solar wind is heated at electron scales
- June 18 - Cluster and Double Star: 1000 publications
- April 29 - Monitoring the impact of extreme solar events
- March 25 - Cluster's insight into space turbulence
- February 9 - ESA extends the Cluster mission until the end of 2009
- January 14 - Cluster detects invisible escaping ions
2008
- December 15 - The science of space weather
- December 5 - Looking at Jupiter to understand Earth
- October 17 - Highlights from Cluster-THEMIS workshop
- August 27 - Cluster examines Earth-escaping ions
- August 11 - Electron trapping within reconnection
- June 27 - Beamed radio emission from Earth
- June 9 - Reconnection - Triggered by Whistlers?
- March 7 - Solitons found in the magnetopause
- January 23 - Cluster result impacts future space missions
2007
- December 6 - Cluster explains nightside ion beams
- November 21 - Cluster captures the impact of a Coronal Mass Ejection
- November 9 - Cluster probes generalized Ohm's law in space
- October 22 - Cluster monitors convection cells over the polar caps
- September 11 - Cluster and Double Star pinpoint the source of bright aurorae
- July 26 - Cluster helps reveal how the Sun shakes the Earth's magnetic field
- June 29 - Cluster unveils a new 3D vision of magnetic reconnection
- June 21 - Formation flying at closest-ever separation
- May 11 - Cluster reveals the reformation of the Earth's bow shock
- April 12 - Cluster finds new clues on what triggers space tsunamis
- March 26 - First direct evidence in space of magnetic reconnection in turbulent plasma
- March 12 - A leap forward in probing magnetic reconnection in space
- February 9 - New insights in the auroral electrical circuit revealed by Cluster
2006
- December 29 - 1000th Orbit for the Cluster Mission
- December 6 - Cluster finds magnetic reconnection within giant swirls of plasma
- November 13 - Cluster takes a new look at the plasmasphere
- October 5 - Double Star and Cluster witness pulsated reconnection for several hours
- August 24 - Cluster links magnetic substorms and Earthward directed high-speed flows
- July 18 - Magnetic heart of a 3D reconnection event revealed by Cluster
- June 20 - Space is fizzy
- May 19 - New Microscopic Properties of Magnetic Reconnection Derived by Cluster
- March 30 - Cluster and Double Star reveal the extent of neutral sheet oscillations
- February 24 - Cluster reveals fundamental 3-D properties of magnetic turbulence
- February 1 - The Cluster Active Archive goes live
- January 11 - Cover of Nature Magazine: Feel the Force
2005
- December 22 - Cluster helps to protect astronauts and satellites against killer electrons
- September 21 - Double Star and Cluster observe first evidence of crustal cracking
- August 10 - From ‘macro’ to ‘micro’ – turbulence seen by Cluster
- July 28 - First direct measurements of the ring current
- July 14 - Five years of formation flying with Cluster
- April 28 - Calming effect of a solar storm
- February 18 - Cluster will become the first multi-scale mission
- February 4 - Direct observation of 3D magnetic reconnection
2004
- December 12 - Cluster determines the spatial scale of high speed flows in the magnetotail
- November 24 Four-point observations of solar wind discontinuities
- September 17 - Cluster locates the source of non-thermal terrestrial continuum radiation by triangulation
- August 12 - Cluster finds giant gas vortices at the edge of Earth's magnetic bubble
- June 23 - Cluster discovers internal origin of the plasma sheet oscillations
- May 13 - Cluster captures a triple cusp
- April 5 - First attempt to estimate Earth's bow shock thickness
2003-2001
- 2003.12.03 - Cracks in Earth's magnetic shield (NASA website)
- 2003.06.29 - Multi-point observations of magnetic reconnection
- 2003.05.20 - ESA's Cluster solves auroral puzzle
- 2003.01.29 - Bifurcation of the tail current
- 2003.01.28 - Electric current measured in space for the first time
- 2002.12.29 - Thickness of the tail current sheet estimated in space for the first time
- 2002.10.01 - Telescopic/Microscopic view of a substorm
- 2001.12.11 - Cluster quartet probes the secrets of the black aurora
- 2001.10.31 - First measurements of density gradients in space
- 2001.10.09 - Double cusp observed by Cluster
- 2001.02.01 - Official start of scientific operations
Selected publications
All 1926 publications related to the Cluster and the Double Star missions (count as of 31 October 2011) can be found on the publication section of the ESA Cluster mission websiteInstrumentation on each Cluster satellite
| Number | Acronym | Instrument | Measurement | Purpose |
|---|---|---|---|---|
| 1 | ASPOC | Active Spacecraft Potential Control experiment | Regulation of spacecraft's electrostatic potential | Enables the measure by PEACE of cold electrons (a few eV temperature), otherwise hidden by spacecraft photoelectrons |
| 2 | CIS | Cluster Ion Spectroscopy experiment | Ion times-of-flight (TOFs) and energies from 0 to 40 keV | Composition and 3D distribution of ions in plasma |
| 3 | DWP | Digital Wave Processing instrument | Coordinates the operations of the EFW, STAFF, WBD and WHISPER instruments. | At the lowest level, DWP provides electrical signals to synchronise instrument sampling. At the highest level, DWP enables more complex operational modes by means of macros. |
| 4 | EDI | Electron Drift Instrument | Electric field E magnitude and direction | E vector, gradients in local magnetic field B |
| 5 | EFW | Electric Field and Wave experiment | Electric field E magnitude and direction | E vector, spacecraft potential, electron density and temperature |
| 6 | FGM | Fluxgate Magnetometer | Magnetic field B magnitude and direction | B vector and event trigger to all instruments except ASPOC |
| 7 | PEACE | Plasma Electron and Current Experiment | Electron energies from 0.0007 to 30 keV | 3D distribution of electrons in plasma |
| 8 | RAPID | Research with Adaptive Particle Imaging Detectors | Electron energies from 30 to 1500 keV, ion energies from 20 to 450 keV | 3D distributions of high-energy electrons and ions in plasma |
| 9 | STAFF | Spatio-Temporal Analysis of Field Fluctuation experiment | Magnetic field B magnitude and direction of EM fluctuations, cross-correlation of E and B | Properties of small-scale current structures, source of plasma waves and turbulence |
| 10 | WBD | Wide Band Data receiver | Electric field E waveforms and spectrograms of terrestrial plasma waves and radio emissions | Motion of terrestrial fluctuations, e.g. auroral kilometric radiation Auroral kilometric radiation Auroral kilometric radiation is the intense radio radiation emitted in the acceleration zone of the polar lights. The radiation mainly comes from cyclotron radiation from electrons orbiting around the magnetic field lines of the Earth... |
| 11 | WHISPER | Waves of High Frequency and Sounder for Probing of Density by Relaxation | Electric field E spectrograms of terrestrial plasma waves and radio emissions in the 2–80 kHz range; triggering of plasma resonances by an active sounder. | Source location of waves by triangulation; electron density within the range 0.2–80 cm−3 |