- Cluster (spacecraft)
Cluster Operator European Space Agency in international collaboration with NASA Major contractors Dornier GmbH (now part of EADS) Mission type Orbiter Satellite of Earth Launch date 16-Jul-2000 12:39 UT and 09-Aug-2000 11:13 UT Launch vehicle Soyuz-FG/Fregat Mission duration 11 years, 2 months and 10 days COSPAR ID 2000-041A Homepage http://sci.esa.int/cluster Mass 1200 kg per satellite Orbital elements Inclination 90 deg (nominal) Orbital period 57 h
Cluster 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. The four Cluster spacecraft were successfully launched by pair in July and August 2000 onboard two Soyuz-Fregat rockets from Baikonur. In February 2011, Cluster 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 from 2003 to 2007.
- 1 Cluster mission overview
- 2 History
- 3 Scientific objectives
- 4 Double Star mission with China
- 5 Discoveries and mission milestones
- 6 References
- 7 Selected publications
- 8 Instrumentation on each Cluster satellite
- 9 External links
Cluster mission overview
The four identical Cluster 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 wind 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 cells provided 224 watts 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 orbits 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 hours to complete. The European Space Operations Centre (ESOC) acquires telemetry and distributes to the online data centers the science data from the spacecraft.
The Cluster mission was proposed to ESA in 1982 and approved in 1986, along with the Solar and Heliospheric Observatory (SOHO). Though the original Cluster spacecraft were completed in 1995, the explosion of the Ariane 5 rocket carrying the satellites in 1996 (during Ariane 5 Flight 501) 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 Clusters (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 Cluster 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 Cluster 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.
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 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.
- The bow shock is the region in space between the Earth and the sun where the solar wind decelerates from super- to sub-sonic before being deflected around the Earth. In traversing this region, Cluster makes measurements which help characterize processes occurring at the bow shock, such as the origin of hot flow anomalies and the transmission of electromagnetic waves through the bow shock and the magnetosheath from the solar wind.
- Behind the bow shock is the thin plasma layer separating the Earth and solar wind magnetic fields known as the magnetopause. 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 ionosphere 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 Administration 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.
Discoveries and mission milestones
- 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
- 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
- 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
- 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
- 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
- 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
- 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
- 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
- 2003.12.03 - 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
- Escoubet, C.P., R. Schmidt and M.L. Goldstein (1997). "Cluster - Science and Mission Overview". Space Sci. Rev. 79: 11–32. Bibcode 1997SSRv...79...11E. doi:10.1023/A:1004923124586. http://www.springerlink.com/content/j2t18q41376h3508/.
- Escoubet, C.P., M. Fehringer and M. Goldstein (2001). "The Cluster mission". Ann. Geophys. 19 (10/12): 1197–1200. Bibcode 2001AnGeo..19.1197E. doi:10.5194/angeo-19-1197-2001. http://www.ann-geophys.net/19/1197/2001/angeo-19-1197-2001.pdf.
- Paschmann, G., S.J. Schwartz, C.P. Escoubet, S. Haaland, ed (2005). Outer Magnetospheric Boundaries: Cluster Results. reprinted from Space Sci. Rev., 118, 1-4, Springer, Berlin. pp. 1–434. http://adsabs.harvard.edu/abs/2005ombc.book.....P.
- Taylor, M., C.P. Escoubet, H. Laakso, A. Masson, M. Goldstein (2010). H. Laakso et al. (eds.). ed. The Cluster Mission: Space Plasma in Three Dimensions. Astrophys. & Space Sci. Proc., Springer. pp. 309–330. http://www.springerlink.com/content/q723348t461612h3/.
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 website
- ^ Shay, M.A., et al. (2011). "Super-Alfvénic Propagation of Substorm Reconnection Signature and Poynting Flux". Physical Review Letters 107 (6): 065001. Bibcode 2011PhRvL.107f5001S. doi:10.1103/PhysRevLett.107.065001.
- ^ Turner, A.J. et al. (2011). "Nonaxisymmetric Anisotropy of Solar Wind Turbulence". Physical Review Letters 107 (9): 095002. Bibcode 2011PhRvL.107i5002T. doi:10.1103/PhysRevLett.107.095002.
- ^ Khotyaintsev, Y. et al. (2-11). "Plasma Jet Braking: Energy Dissipation and Nonadiabatic Electrons". Physical Review Letters 106 (16): 165001. Bibcode 2011PhRvL.106p5001K. doi:10.1103/PhysRevLett.106.165001.
- ^ Marklund, G.T. et al. (2011). "Altitude distribution of the auroral acceleration potential determined from Cluster satellite data at different heights". Physical Review Letters 106 (5): 055002. Bibcode 2011PhRvL.106e5002M. doi:10.1103/PhysRevLett.106.055002.
- ^ Echim, M. et al. (2011). "Comparative investigation of the terrestrial and Venusian magnetopause: Kinetic modeling and experimental observations by Cluster and Venus Express". Planet. Space Sci., in press. Bibcode 2011P&SS...59.1028E. doi:10.1016/j.pss.2010.04.019. http://www.sciencedirect.com/science/article/B6V6T-5017HNW-1/2/1c0920afbad19aa087ecd56ecdefb80b.
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Instrumentation 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 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
- ESA Cluster mission website
- More on spacecraft operations
- Imperial College London role in the Cluster mission
- NASA Cluster mission profile
Magnetospherics Submagnetosphere Earth's magnetosphere Solar wind Satellites Research projects Other magnetospheres Related topics European Space Agency
Ariane 5 · Vega (2012)FacilitiesCommunicationsProgrammesPredecessorsRelated
ProjectsScienceSolar PhysicsPlanetary ScienceGiotto (1985-1992) · Huygens (1997-2005) · SMART-1 (2003-2006) · Mars Express (2003-present) · Rosetta (2005-present) · Venus Express (2005-present) · BepiColombo (2014) · ExoMars Trace Gas Orbiter (2016) · ExoMars EDM (2016) · ExoMars Rover (2018) · Mars sample return mission (proposal/2020-2022) · Jupiter Icy Moon Explorer (proposal/2020) · MarcoPolo-R (proposal/2022)Astronomy
and CosmologyCos-B (1975-1982) · IUE (1978-1996) · EXOSAT (1983-1986) · Hipparcos (1989-1993) · Hubble (1990-present) · Eureca (1992-1993) · ISO (1995-1998) · XMM-Newton (1999-present) · INTEGRAL (2002-present) · COROT (2006-present) · Planck (2009-present) · Herschel (2009-present) · Gaia (2013) · JWST (2018) · Euclid (2019) · IXO (proposal/2020) · LISA (proposal/2020) · EChO (proposal/2022) · LOFT (proposal/2022) · Plato (proposal/2022) · STE-QUEST (proposal/2022)Earth ObservationMeteosat First Generation (1977-1997) · ERS-1 (1991-2000) · ERS-2 (1995-2011) · Meteosat Second Generation (2002-present) · Envisat (2002-present) · Double Star (2003-2007) · MetOp-A (2006-present) · GOCE (2009-present) · SMOS (2009-present) · CryoSat-2 (2010-present) · Swarm (2012) · Sentinel 1 (2013) · ADM-Aeolus (2013) · Sentinel 2 (2014) · EarthCARE (2016) · Sentinel 3 (2017) · Meteosat Third Generation (2017)Human
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