Cluster II was a space mission of the

European Space Agency The European Space Agency (ESA) is a 23-member International organization, international organization devoted to space exploration. With its headquarters in Paris and a staff of around 2,547 people globally as of 2023, ESA was founded in 1975 ...

, with

NASA The National Aeronautics and Space Administration (NASA ) is an independent agencies of the United States government, independent agency of the federal government of the United States, US federal government responsible for the United States ...

participation, to study the

Earth Earth is the third planet from the Sun and the only astronomical object known to Planetary habitability, harbor life. This is enabled by Earth being an ocean world, the only one in the Solar System sustaining liquid surface water. Almost all ...

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 ...

over the course of nearly two

solar cycle The Solar cycle, also known as the solar magnetic activity cycle, sunspot cycle, or Schwabe cycle, is a periodic 11-year change in the Sun's activity measured in terms of Modern Maximum, variations in the number of observed sunspots on the Sun ...

s. The mission was composed of four identical spacecraft flying in a

tetrahedral In geometry, a tetrahedron (: tetrahedra or tetrahedrons), also known as a triangular pyramid, is a polyhedron composed of four triangular Face (geometry), faces, six straight Edge (geometry), edges, and four vertex (geometry), vertices. The tet ...

formation. As a replacement for the original

Cluster may refer to: Science and technology Astronomy * Cluster (spacecraft), constellation of four European Space Agency spacecraft * Cluster II (spacecraft), a European Space Agency mission to study the magnetosphere * Asteroid cluster, a small ...

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 Soyuz (, GRAU index: 11A511) is a family of Soviet and later Russian expendable medium-lift launch vehicles initially developed by the OKB-1 design bureau and manufactured by the Progress Rocket Space Centre factory in Samara, Russia. It hold ...

rocket A rocket (from , and so named for its shape) is a vehicle that uses jet propulsion to accelerate without using any surrounding air. A rocket engine produces thrust by reaction to exhaust expelled at high speed. Rocket engines work entirely ...

s from

Baikonur Baikonur ( ; ) is a city in Kazakhstan on the northern bank of the Syr Darya river. It is currently leased and administered by the Russian Federation as an enclave until 2050. It was constructed to serve the Baikonur Cosmodrome with adminis ...

Kazakhstan Kazakhstan, officially the Republic of Kazakhstan, is a landlocked country primarily in Central Asia, with a European Kazakhstan, small portion in Eastern Europe. It borders Russia to the Kazakhstan–Russia border, north and west, China to th ...

. In February 2011, Cluster II celebrated 10 years of successful scientific operations in space. In February 2021, Cluster II celebrated 20 years of successful scientific operations in space. , its mission was extended until September 2024. The

China National Space Administration The China National Space Administration (CNSA) is a government agency of the People's Republic of China headquartered in Haidian District, Haidian, Beijing, responsible for civil space administration and international space cooperation. These ...

/ESA

Double Star mission Double Star was a joint satellite based space mission by the China National Space Administration (CNSA) and the European Space Agency (ESA). It was the first space mission launched by China to investigate Earth's magnetosphere. It consisted of ...

operated alongside Cluster II from 2004 to 2007. The first of the satellites of Cluster II to re-enter the atmosphere did so on 8 September 2024. The remaining three are expected to follow in 2025 and 2026. The scientific payload operations of all satellites ended as the first satellite re-entered the atmosphere (other flight operations are still being performed with the remaining flying satellites until the satellites have all re-entered).

Mission overview

The four identical Cluster II satellites studied 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 was able to collect three-dimensional information on how the

solar wind The solar wind is a stream of charged particles released from the Sun's outermost atmospheric layer, the Stellar corona, corona. This Plasma (physics), plasma mostly consists of electrons, protons and alpha particles with kinetic energy betwee ...

interacts with the

and affects near-Earth space and its

atmosphere An atmosphere () is a layer of gases that envelop an astronomical object, held in place by the gravity of the object. A planet retains an atmosphere when the gravity is great and the temperature of the atmosphere is low. A stellar atmosph ...

, including aurorae. The spacecraft were cylindrical (2.9 x 1.3 m, se
online 3D model
and were spinning at 15 rotations per

minute A minute is a unit of time defined as equal to 60 seconds. It is not a unit in the International System of Units (SI), but is accepted for use with SI. The SI symbol for minutes is min (without a dot). The prime symbol is also sometimes used i ...

. After launch, their

solar cell A solar cell, also known as a photovoltaic cell (PV cell), is an electronic device that converts the energy of light directly into electricity by means of the photovoltaic effect.

s provided 224

watt The watt (symbol: W) is the unit of Power (physics), power or radiant flux in the International System of Units (SI), equal to 1 joule per second or 1 kg⋅m2⋅s−3. It is used to quantification (science), quantify the rate of Work ...

s power for instruments and communications. Solar array power gradually declined as the mission progressed, due to damage by energetic charged particles, but this was planned for and the power level remains sufficient for science operations. The four spacecraft maneuvered into various tetrahedral formations to study the magnetospheric structure and boundaries. The inter-spacecraft distances could be altered and varied from around 4 to 10,000 km. The

propellant A propellant (or propellent) is a mass that is expelled or expanded in such a way as to create a thrust or another motive force in accordance with Newton's third law of motion, and "propel" a vehicle, projectile, or fluid payload. In vehicle ...

for the transfer to the operational orbit, and the maneuvers to vary inter-spacecraft separation distances made up approximately half of the spacecraft's launch weight. The highly elliptical

orbit In celestial mechanics, an orbit (also known as orbital revolution) is the curved trajectory of an object such as the trajectory of a planet around a star, or of a natural satellite around a planet, or of an artificial satellite around an ...

s of the spacecraft initially reached 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 around 4 R_E (Earth radii, where 1 R_E = 6371 km) and 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 19.6 R_E. Each orbit took approximately 57

hour An hour (symbol: h; also abbreviated hr) is a unit of time historically reckoned as of a day and defined contemporarily as exactly 3,600 seconds ( SI). There are 60 minutes in an hour, and 24 hours in a day. The hour was initially establis ...

s to complete. The orbit evolved over time; the line of apsides rotated southwards so that the distance at which the orbit crossed the magnetotail current sheet progressively reduced, and a wide range of dayside magnetopause crossing latitudes were sampled. Gravitational effects imposed a long term cycle of change in the perigee (and apogee) distance, which saw the perigees reduce to a few 100 km in 2011 before beginning to rise again. The orbit plane rotated away from 90 degrees inclination. Orbit modifications by ESOC altered the orbital period to 54 hours. All these changes allowed Cluster to visit a much wider set of important magnetospheric regions than was possible for the initial 2-year mission, improving the scientific breadth of the mission. The

European Space Operations Centre The European Space Operations Centre (ESOC) serves as the main mission control centre for the European Space Agency (ESA) and is located in Darmstadt, Germany. ESOC's primary function is the operation of uncrewed spacecraft on behalf of ESA and ...

(ESOC) acquired

telemetry Telemetry is the in situ collection of measurements or other data at remote points and their automatic transmission to receiving equipment (telecommunication) for monitoring. The word is derived from the Greek roots ''tele'', 'far off', an ...

and distributed to the online data centers the science data from the spacecraft. The Joint Science Operations Centre (JSOC) at Rutherford Appleton Laboratory in the UK coordinated scientific planning and in collaboration with the instrument teams provided merged instrument commanding requests to ESOC. Th
Cluster Science Archive
is the ESA long term archive of the Cluster and Double Star science missions. Since 1 November 2014, it is the sole public access point to the Cluster mission scientific data and supporting datasets. The Double Star data are publicly available via this archive. The Cluster Science Archive is located alongside all the other ESA science archives at the European Space Astronomy Center, located near Madrid, Spain. From February 2006 to October 2014, the Cluster data could be accessed via th
Cluster Active Archive

History

The

mission was proposed to ESA in 1982 and approved in 1986, along with the

Solar and Heliospheric Observatory The Solar and Heliospheric Observatory (SOHO) is a European Space Agency (ESA) spacecraft built by a European industrial consortium led by Matra Marconi Space (now Airbus Defence and Space) that was launched on a Lockheed Martin Atlas IIAS la ...

(SOHO), and together these two missions constituted the Solar Terrestrial Physics "cornerstone" of ESA's Horizon 2000 missions programme. Though the original Cluster spacecraft were completed in 1995, the explosion of the

Ariane 5 Ariane 5 is a retired European heavy-lift space launch vehicle operated by Arianespace for the European Space Agency (ESA). It was launched from the Guiana Space Centre (CSG) in French Guiana. It was used to deliver payloads into geostationar ...

rocket carrying the satellites in 1996 delayed the mission by four years while new instruments and spacecraft were built. On July 16, 2000, a Soyuz-Fregat rocket from the

Baikonur Cosmodrome The Baikonur Cosmodrome is a spaceport operated by Russia within Kazakhstan. Located in the Kazakh city of Baikonur, it is the largest operational space launch facility in terms of area. All Russian Human spaceflight, crewed spaceflights are l ...

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 kilometre

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, was 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

ran a competition to name the satellites across all of the ESA member states. Ray Cotton, from the

United Kingdom The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Northwestern Europe, off the coast of European mainland, the continental mainland. It comprises England, Scotlan ...

, won the competition with the names Rumba,

Tango Tango is a partner dance and social dance that originated in the 1880s along the Río de la Plata, the natural border between Argentina and Uruguay. The tango was born in the impoverished port areas of these countries from a combination of Arge ...

, Salsa and

Samba Samba () is a broad term for many of the rhythms that compose the better known Brazilian music genres that originated in the Afro-Brazilians, Afro Brazilian communities of Bahia in the late 19th century and early 20th century, It is a name or ...

. Ray's town of residence,

Bristol Bristol () is a City status in the United Kingdom, cathedral city, unitary authority area and ceremonial county in South West England, the most populous city in the region. Built around the River Avon, Bristol, River Avon, it is bordered by t ...

, was awarded with scale models of the satellites in recognition of the winning entry, as well as the city's connection with the satellites. However, after many years of being stored away, they were finally given a home at the Rutherford Appleton Laboratory. Originally planned to last until the end of 2003, the mission was extended several times. The first extension took the mission from 2004 until 2005, and the second from 2005 to June 2009. The mission was ultimately extended until September 2024, when the scientific payload operations on the satellites ended. The ultimate end of the Cluster project (especially the Cluster II satellites) will happen in 2026 as the last satellite enters the atmosphere and is destroyed.

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 plasma comprising the magnetosphere cannot be viewed using remote sensing techniques, satellites must be used to measure it in-situ. Four spacecraft allowed 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 carried 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 In astrophysics, bow shocks are shock waves in regions where the conditions of density and pressure change dramatically due to blowing stellar wind. Bow shock occurs when the magnetosphere of an astrophysical object interacts with the nearby fl ...

magnetopause The magnetopause is the abrupt boundary between a magnetosphere and the surrounding Plasma (physics), plasma. For planetary science, the magnetopause is the boundary between the planet's magnetic field and the solar wind. The location of the ma ...

, polar cusps,

magnetotail 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. ...

, plasmapause boundary layer and over the polar caps and the auroral zones. * The ''

'' is the region in space between the Earth and the

Sun The Sun is the star at the centre of the Solar System. It is a massive, nearly perfect sphere of hot plasma, heated to incandescence by nuclear fusion reactions in its core, radiating the energy from its surface mainly as visible light a ...

where the solar wind decelerates from super- to sub-sonic before being deflected around the Earth. In traversing this region, the spacecraft made measurements which helped characterize processes occurring at the bow shock, such as the origin of hot flow anomalies and the transmission of

electromagnetic 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 ...

waves through the bow shock and the

magnetosheath The 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 wit ...

from the solar wind. * Behind the bow shock is the thin plasma layer separating the Earth and solar wind magnetic fields known as 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 made 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 southern, 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 recorded the particle distributions, which allowed 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 In the magnetosphere, the plasma sheet is a sheet-like region of denser (0.3-0.5 ions/cm3 versus 0.01-0.02 in the lobes) hot plasma and lower magnetic field A magnetic field (sometimes called B-field) is a physical field that describes the m ...

forms the inner magnetotail, which is highly active. Cluster monitored particles from the

ionosphere 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 the solar wind as they passed through the magnetotail lobes. In the central plasma sheet, Cluster determined 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 measured the time variations of transient particle flows and electric and magnetic fields in the region.

Instrumentation on each Cluster satellite

Double Star mission with China

In 2003 and 2004, the

launched the

Double Star In observational astronomy, a double star or visual double is a pair of stars that appear close to each other as viewed from Earth, especially with the aid of optical telescopes. This occurs because the pair either forms a binary star (i.e. a ...

satellites, TC-1 and TC-2, that worked together with Cluster to make coordinated measurements mostly within the

. TC-1 stopped operating on 14 October 2007. The last data from TC-2 was received in 2008. TC-2 made a contribution to magnetar science as well as to magnetospheric physics. The TC-1 examined density holes near the Earth's

that can play a role in bow shock formation and looked at neutral sheet oscillations.

Awards

Cluster team awards: *2024 British Interplanetary Society Sir Arthur Clarke Award to the UK Cluster Mission Team *2019 Royal Astronomical Society Group Achievement Award *2015 ESA 15th anniversary award *2013 ESA team award *2010 International Academy of Astronautics Laurels for team achievements for Cluster and Double Star teams *2005 ESA Cluster 5th anniversary award *2004 NASA group achievement award *2000 Popular science best of what's new award *2000 ESA Cluster launch award Individual awards: *2023 Hermann Opgenoorth (Univ. of Umea, Sweden), former Cluster Ground Based Working Group lead, was awarded the 2023 EGU Julius Bartels Medal *2020 Daniel Graham (Swedish Institute of Space Physics, Uppsala, Sweden) was awarded the COSPAR Zeldovich medal *2019 Margaret Kivelson (UCLA, USA), Cluster FGM CoI, received RAS gold medal *2018 Hermann Opgenoorth (Univ. of Umea, Sweden), former Cluster Ground Based Working Group lead, was awarded the 2018 Baron Marcel Nicolet Space Weather and Space Climate medal *2016 Stephen Fuselier (SWRI, USA), Cluster CIS CoI, received EGU Hannes Alfvén Meda *2016 Mike Hapgood, Cluster mission scientific operations expert was awarded the Baron Marcel Nicolet Medal for Space Weather and Space Climate *2014 Rumi Nakamura (IWF, Austria), Cluster CIS/EDI/FGM CoI, received EGU Julius Bartels Medal *2013 Mike Hapgood (RAL, UK), Cluster JSOC project scientist received RAS service award *2013 Göran Marklund, EFW Co-I, received the EGU Hannes Alfvén Medal 2013. *2013 Steve Milan, Cluster Ground based representative of the Cluster mission received UK Royal Astronomical Society (RAS) Chapman medal *2012 Andrew Fazakerley, Cluster and Double Star PI (PEACE), received the Royal Astronomical Society Chapman Medal *2012 Zuyin Pu (Pekin U., China), RAPID/CIS/FGM CoI, received AGU International Award *2012 Jolene Pickett (Iowa U., USA), a Cluster WBD PI, received the State of Iowa Board of Regents Staff Excellence *2012 Jonathan Eastwood (Imperial College, UK), FGM Co-I, received COSPAR Yakov B. Zeldovich medal *2008 Andre Balogh (Imperial College, UK), Cluster FGM PI, received RAS Chapman medal *2006 Steve Schwartz (QMW, UK), Cluster UK data system scientist and PEACE co-I, received RAS Chapman medal

Discoveries and mission milestones

2024

* September 8 - Re-entry of ''SALSA'' (Cluster 2) satellite, the first of the Cluster II satellites to re-enter the atmosphere

2023

* April 28 - Magnetic reconnection at high and low latitudes during the passage of an ICME * March 24 - Properties of the Martian Magnetotail compared Cluster data in the Earth magnetotail * March 23 - Scaling laws for the energy transfer in space plasma turbulence * March 01 - Turbulent MHD cascade in the Jovian magnetosheath compared to Cluster measurements * January 26 - Evidence for lunar tide effects in Earth’s plasmasphere * January 20 - Ion Outflow in Middle Altitude LLBL/Cusp from Different Origins

2022

* December 05 - Magnetosphere distortions during the “satellite killer” storm of February 3–4, 2022 * October 14 - New insights on the formation of transpolar auroral arc * September 20 - A highway for atmospheric ion escape from Earth during the impact of an interplanetary coronal mass ejection * August 03 - Joint Cluster/ground-based studies in the first 20 years of the Cluster mission * July 18 – In situ observation of a magnetopause indentation that is correspondent to throat aurora and is caused by magnetopause reconnection * June 16 - Kelvin-Helmholtz vortices as an interplay of Magnetosphere-Ionosphere coupling * June 02 - ESA highlight: Magnetic vortices explain mysterious auroral beads * May 16 - The influence of localized dynamics on dusk-dawn convection in the Earth’s magnetotail * April 1 - Dawn-dusk ion flow asymmetry in the plasma sheet * February 1 - South Pole Station ground-based and Cluster satellite measurements of leaked and escaping Auroral Kilometric Radiation * January 1 - Massive multi-mission statistical study and analytical modeling of the Earth's magnetopause

2021

* December 15 - ESA highlight: Swarm and Cluster get to the bottom of geomagnetic storms * November 7 - Unique MMS and Cluster observations about magnetic reconnection extent at the magnetopause * November 2 - Spatial distribution of energetic protons in the magnetosphere based on 17 years of data * October 11 - Unique MMS and Cluster observation of disturbances in the near-Earth magnetotail before a magnetic substorm * September 7 - AGU EOS spotlight: Understanding Aurora Formation with ESA’s Cluster Mission * May 2 - Cluster and MMS uncover anisotropic spatial correlation functions at kinetic range in the magnetosheath turbulence * April 9 - The Solar-cycle Variations of the Anisotropy of Taylor Scale and Correlation Scale in the Solar Wind Turbulence * February 18 - Heavy Metal and Rock in Space: Cluster RAPID Observations of Fe and Si

2020

* December 1 - Cluster, Helios and Ulysses reveal characteristics of solar wind supra thermal halo electrons * November 1 - Cluster, Swam and CHAMP join forces to explain hemispheric asymmetries in the Earth magnetotail * October 21 - Space plasma regimes classified with Cluster data * October 1 - Effects of Solar Activity on Taylor Scale and Correlation Scale in Solar Wind Magnetic Fluctuations * September 1 - Van Allen Probes and Cluster join forces to study Outer Radiation Belt Electrons * August 9 - Cluster’s 20 years of studying Earth’s magnetosphere], celebrating 20 years after the launch of the second pair of Cluster spacecraft * July 31 - ESA science highlight: Auroral substorms triggered by short circuiting of plasma flows * July 16 - BBC skyatnight podcast with Dr. Mike Hapgood on 20 years of ESA’s Cluster mission, celebrating 20 years after the launch of the first pair of Cluster satellites * April 20 - What drives some of the largest and most dynamic auroral forms? * March 19 - ESA science highlight: Iron is everywhere in Earth's vicinity, suggest two decades of Cluster data * February 27 - What makes Kelvin Helmholtz vortices grow at the Earth's magnetopause?

2019

* December 23 - Magnetized dust clouds penetrate the terrestrial bow shock * November 18 - Earth’s magnetic song recorded for the first time during a solar storm *October 10 - What is the source of the energetic oxygen ions found in the high-altitude cusp region? *August 27 - Cluster and XMM pave the way for SMILE *August 20 - Asymmetric transport of the Earth's polar outflows by the interplanetary magnetic field *August 5 - Energetic electron acceleration found by Cluster in unconfined reconnection jets for the first time *May 1 - Kelvin‐Helmholtz waves magnetic curvature and vorticity: Four‐spacecraft Cluster observations *March 4
ESA science highlight: Cluster helps solve mysteries of geomagnetic storms
*February 27
ESA science highlight: Cluster reveals inner workings of Earth's cosmic particle accelerator
*February 13
Statistical survey of the terrestrial bow shock observed by the Cluster spacecraft
*January 14
Super-efficient electron acceleration by an isolated magnetic reconnection

2018

*November 28 �
Complete picture of the O+ circulation (and escape) in the outer magnetosphere and its dependence on geomagnetic activity
*November 8
ESA science highlight: Windy with a chance of magnetic storms – space weather science with Cluster
*September 30
O+ escape during the extreme space weather event of 4–10 September 2017
*August 8
Statistical survey of day-side magnetospheric current flow using Cluster observations: bow shock
*June 20 �
Detection of magnetic nulls around reconnection fronts (open access)
*May 21 �
Tailward propagation of magnetic energy density variations with respect to substorm onset times (open access)
*April 24 �
Kelvin–Helmholtz Instability: lessons learned and ways forward
*March 29 �
Three-dimensional density and compressible magnetic structure in solar wind turbulence
*February 8 �
ESA spotlight on... Understanding Earth: what the Cluster mission has taught us so far
*January 29 �
ESA research highlight: Cluster measures turbulence in Earth's magnetic environment
*January 22 �
Science nugget of the 2013-2014 Cluster Inner Magnetosphere campaign

2017

*December 11, 2017 �
Empirical modeling of the quiet and storm time geosynchronous magnetic field
ref name="Andreeva V.A. and Tsyganenko N.A., 2017"> *December 6, 2017 �
Direct measurement of anisotropic and asymmetric wave vector spectrum in ion-scale solar wind turbulence
ref name="Roberts et al., 2017"> *October 30, 2017 �
Coherent structures at ion scales in the fast solar wind: Cluster observations
*September 18, 2017 �
An intense magnetic substorm scrutinized by a fleet of satellites including Cluster and MMS (open access)
*August 28, 2017 �
Relationship between electron field‐aligned anisotropy and dawn‐dusk magnetic field: nine years of Cluster observations in the Earth magnetotail
*August 1, 2017 �
Collisionless shock velocity estimation at Venus and Earth (open access)
*June 16, 2017 �
Cover of GRL: Global ULF waves generated by a hot flow anomaly
*April 10, 2017
ESA research highlight: O marks the spot for magnetic reconnection
*April 7, 2017 �
EOS research spotlight: Explaining unexpected twists in the Sun's Magnetic Field
ref name="Turc et al., 2017"> *March 23, 2017 �
Occurrence frequency and location of magnetic islands at the dayside magnetopause
*February 18, 2017 �
Magnetic reconnection and their associated auroral enhancements (open access)

2016

*October 3, 2016 �
What happens to the Earth's magnetosphere when its bow shock disappears?
ref name="Lugaz et al., 2016"> *September 6, 2016 �
Embry-Riddle University (FL, USA) science highlight: Space plasma hurricanes could lead to new sources of energy
ref name="Moore et al., 2016"> *July 20, 2016 �
Cluster and MMS join forces to understand the origin of northern lights
ref name="Schmid et al., 2016"> *July 8 �
Transport of solar wind H+ and He++ ions across Earth's bow shock
*July 7 �
ESA science highlight: the curious case of Earth's leaking atmosphere
ref name="Lee et al., 2016"> *June 11 �
Substructures within a dipolarization front revealed by high-temporal resolution Cluster observations
*May 11 �
Cone angle control of the interaction of magnetic clouds with the Earth's bow shock
*March 21 �
The particle carriers of field‐aligned currents in the Earth's magnetotail during a substorm
*February 29 �
The role of ionospheric O+ outflow in the generation of earthward propagating plasmoids
ref name="Zhang et al., 2016"/> *January 11 �
A statistical study of plasmaspheric plumes and ionospheric outflows observed at the dayside magnetopause
ref name="Lee et al., 2016"/>

2015

*December 7

*October 22 - ttps://www.ann-geophys.net/33/1285/2015/angeo-33-1285-2015.pdf# Wide-banded Non-Thermal Continuum (NTC) radiation: local to remote observations by the four Cluster satellites *September 3
Statistics and accuracy of magnetic null identification in multispacecraft data (open access)
*August 22
Cusp dynamics under northward IMF using three‐dimensional global particle‐in‐cell simulations (open access)
*July 14
Cluster solves the mystery of equatorial noise
*July 1
Seven ESA satellites team up to explore the Earth's magnetic field
*April 9
Heart of the black auroras revealed by Cluster
*March 25
Cluster satellite catches up
*February 19
Magnetospheric signatures of ionospheric density cavities observed by Cluster (open access)
*February 16
Solar illumination control of ionospheric outflow above polar cap arcs (open access)
*January 16 �
Rejigging the Cluster quartet at the bow shock and in the solar wind

2014

*December 18 �
Origin of high-latitude auroras revealed
*November 20
The Cluster mission is extended by ESA up to 2018
*September 4
Full particle electromagnetic simulations of entropy generation across a collisionless shock
*August 28 �
A mixed-up magnetic storm
*July 1
Dawn–dusk asymmetries in the coupled solar wind–magnetosphere–ionosphere system: a review
*June 15
Solar wind breaks through the Earth's magnetic field
*May 28
Evidence of strong energetic ion acceleration in the near‐Earth magnetotail (free access)
*May 7
Cluster helps to model Earth's mysterious magnetosphere
*March 15
Direct calculation of the ring current distribution and magnetic structure seen by Cluster during geomagnetic storms (open access)
*January 13
Low-altitude electron acceleration due to multiple flow bursts in the magnetotail (open access)

2013

*November 26
Cluster takes a tilt at radio wave sources
*November 15 �
On the relation between asymmetries in the ring current and magnetopause current (free access)
*September 20
ESA's Cluster satellites in closest-ever 'dance in space'
*September 10 �
Cluster shows plasmasphere interacting with Van Allen belts
*July 18
Wobbly magnetic reconnection speeds up electrons
*July 2
Cluster discovers steady leak in the Earth's plasmasphere
*May 2
Cluster hears the heartbeat of magnetic reconnection
*April 15
From solar activity to stunning aurora (ESA Space Science's image of the week)
*April 10 �
Cluster finds source of aurora energy boost

2012

*December 18 �
The solar wind is swirly
*October 24
Cluster observes a 'porous' magnetopause
*August 1 �
Cluster looks into waves in the magnetosphere's thin boundaries
*July 2

*June 6 �
Origin of particle acceleration in cusps of Earth's magnetosphere uncovered
*March 7

*February 27

*February 23
Surprise Ions (Science News for kids)
*January 26
Giant veil of cold plasma discovered high above Earth (National Geographic)
*January 24 �
Elusive matter found to be abundant far above Earth (AGU press release)

2011

*November 16 �
Cluster reveals Earth's bow shock is remarkably thin
*September 6 �
Ultra fast substorm auroras explained
*August 31

*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

*March 21

*February 5 �

*January 7
ESA spacecraft model magnetic boundaries

2010

*November 22
ESA extends the Cluster mission until December 2014
*October 4 �

*September 1
10 years of success for Cluster quartet
* July 26
Cluster makes crucial step in understanding space weather
* July 16

* 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

*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

*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 2
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
ref name="Hasegawa et al., 2004"> *June 23
Cluster discovers internal origin of the plasma sheet oscillations
*May 13
Cluster captures a triple cusp
*May 11
Cluster observes finite amplitude Alfvén waves and small-scale magnetic filaments downstream of a quasi-perpendicular shock
*April 5
First attempt to estimate Earth's bow shock thickness

2001–2003

*3 December 2003
Cracks in Earth's magnetic shield (NASA website)
*29 June 2003
Multi-point observations of magnetic reconnection
*20 May 2003
ESA's Cluster solves auroral puzzle
*29 January 2003
Bifurcation of the tail current
*28 January 2003
Electric current measured in space for the first time
*29 December 2002
Thickness of the tail current sheet estimated in space for the first time
*1 October 2002
Telescopic/Microscopic view of a substorm
*11 December 2001
Cluster quartet probes the secrets of the black aurora
*31 October 2001
First measurements of density gradients in space
*9 October 2001
Double cusp observed by Cluster
ref> *1 February 2001 �
Official start of scientific operations

References

* * * * * *

Selected publications

All 3793 publications related to the Cluster and the Double Star missions (count as of 31 March 2025) can be found on th
publication section of the ESA Cluster mission website
Among these publications, 3297 are refereed publications, 342 proceedings, 124 PhDs and 31 other types of theses.

External links

ESA Cluster mission websiteThe Cluster Science Archive
the public data archive of the Cluster and the Double Star missions
ESA Cluster mission Twitter accountImperial College London role in the Cluster missionUniversity College London's Mullard Space Science Laboratory's role in the Cluster mission

Cluster: aurora explorer, an exhibit at the Royal Society Summer Exhibition 2011The Cluster Active Archive
(former public data archive, up to 2014)
Cluster mission article on eoPortal by ESA
{{DEFAULTSORT:Cluster (Spacecraft) European Space Agency space probes 2000 in spaceflight Geospace monitoring satellites Geomagnetic satellites