Cluster II (spacecraft)

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This article is about the current, replacement Cluster mission. For the original, failed mission, see, see Cluster (spacecraft).
Cluster II
Operator European Space Agency in international collaboration with NASA
Major contractors Dornier GmbH (now part of EADS)
Mission type Orbiter
Launch date 16-Jul-2000 12:39 UT (Salsa and Samba) and 09-Aug-2000 11:13 UT (Rumba and Tango)
Launch vehicle Soyuz-U/Fregat
Mission duration 13 years, 5 months, and 9 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 II[1] 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 rockets from Baikonur, Kazakhstan. In February 2011, Cluster II celebrated 10 years of successful scientific operations in space. The mission has been extended until December 2014. China National Space Administration/ESA Double Star mission operated alongside Cluster II from 2004 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 wind interacts with the magnetosphere and affects near-Earth space and its atmosphere, including aurorae.

The spacecraft are cylindrical (2.9 x 1.3 m, see online 3D model) and are spinning at 15 rotations per minute. After launch, their solar cells provided 224 watts power for instruments and communications. Solar array power has 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 maneuver into various tetrahedral formations to study the magnetospheric structure and boundaries. The inter-spacecraft distances can be altered and has varied from around 4 to 10,000 km. The propellant 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 orbits of the spacecraft initially reached a perigee of around 4 RE (Earth radii, where 1 RE = 6371 km) and an apogee of 19.6 RE. Each orbit took approximately 57 hours to complete. The orbit has evolved over time; the line of apsides has 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 impose 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 has rotated away from 90 degrees inclination. Orbit modifications by ESOC have altered the orbital period to 54 hours. All these changes have 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 (ESOC) acquires telemetry and distributes to the online data centers the science data from the spacecraft. The Joint Science Operations Centre JSOC at Rutherford Appleton Laboratory in the UK coordinates scientific planning and in collaboration with the instrument teams provides merged instrument commanding requests to ESOC.

All scientific data from the mission is being made available via the Cluster Active Archive (shortly to become the Cluster Science Archive)

History

The Cluster mission was proposed to ESA in 1982 and approved in 1986, along with the Solar and Heliospheric Observatory (SOHO), and together these two missions consitituted 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 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 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 European Space Agency ran a competition to name the satellites across all of the ESA member states.[2] Ray Cotton, from the United Kingdom, won the competition with the names Rumba, Tango, Salsa and Samba.[3] Ray's town of residence, Bristol, was awarded with scale models of the satellites in recognition of the winning entry,[4][5] 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 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 the end of 2014.

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 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, 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 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.

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 39 to 406 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

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. The last data from TC-2 was received in 2008. TC-2 made a contribution to magnetar science as well as to magnetospheric physics.

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 equipment 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

2013

2012

2011

2010

2009

2008

2007

2006

2005

2004

2003-2001

References

Selected publications

All 2351 publications related to the Cluster and the Double Star missions (count as of 31 December 2013) can be found on the publication section of the ESA Cluster mission website

  1. ↑ "Cluster II operations". European Space Agency. Retrieved 29 November 2011. 
  2. ↑ "European Space Agency Announces Contest to Name the Cluster Quartet". European Space Agency. 
  3. ↑ "Bristol and Cluster - the link". European Space Agency. Retrieved 2 September 2013. 
  4. ↑ "Cluster II - Scientific Update and Presentation of Model to the City of Bristol". SpaceRef Interactive Inc. 
  5. ↑ "Cluster - Presentation of model to the city of Bristol and science results overview". European Space Agency. 
  6. ↑ Décréau, P.M.E., et al. (2013). "Remote sensing of a NTC radio source from a Cluster tilted spacecraft pair". Ann. Geophys. 31: 2097–2121. doi:10.5194/angeo-31-2097-2013. 
  7. ↑ Darrouzet, F., et al. (2013). "Links between the plasmapause and the radiation belt boundaries as observed by the instruments CIS, RAPID, and WHISPER onboard Cluster". J. Geophys. Res. 118: 4176–4188. Bibcode:2013JGRA..118.4176D. doi:10.1002/jgra.50239. 
  8. ↑ Fu, H.S., et al. (2013). "Energetic electron acceleration by unsteady magnetic reconnection". Nature Physics 9: 426–430. Bibcode:2013NatPh...9..426F. doi:10.1038/nphys2664. 
  9. ↑ Dandouras, I. (2013). "Detection of a plasmaspheric wind in the Earth's magnetosphere by the Cluster spacecraft". Ann. Geophys. 31 (7): 1143–1153. Bibcode:2013AnGeo..31.1143D. doi:10.5194/angeo-31-1143-2013. 
  10. ↑ Viberg, H., et al. (2013). "Mapping High-Frequency Waves in the Reconnection Diffusion Region". Geophys. Res. Lett. 40 (6): 1032–1037. Bibcode:2013GeoRL..40.1032V. doi:10.1002/grl.50227. 
  11. ↑ Cao, J., et al. (2013). "Kinetic analysis of the energy transport of bursty bulk flows in the plasma sheet". J. Geophys. Res. Space Physics 118 (1): 313–320. Bibcode:2013JGRA..118..313C. doi:10.1029/2012JA018351. 
  12. ↑ Perri, S., et al. (2012). "Detection of small scale structures in the dissipation regime of solar wind turbulence". Phys. Rev. Lett. 109 (19). Bibcode:2012PhRvL.109s1101P. doi:10.1103/PhysRevLett.109.191101. 
  13. ↑ Hwang, K.-J. et al. (2012). "The first in situ observation of Kelvin-Helmholtz waves at high-latitude magnetopause during strongly dawnward interplanetary magnetic field conditions". J. Geophys. Res. 117: A08233. Bibcode:2012JGRA..11708233H. doi:10.1029/2011JA017256. 
  14. ↑ Norgren, C. et al. (2012). "Lower hybrid drift waves: space observations". Physical Review Letters 109 (5): 55001. Bibcode:2012PhRvL.109e5001N. doi:10.1103/PhysRevLett.109.055001. 
  15. ↑ Nykyri, K., et al. (2012). "On the origin of high-energy particles in the cusp diamagnetic cavity". Journal of Atmospheric and Solar-Terrestrial Physics (Special Issue on Physical Process in the Cusp: Plasma Transport and Energization). Bibcode:2012JASTP..87...70N. doi:10.1016/j.jastp.2011.08.012. 
  16. ↑ Wei, Y., et al. (2012). "Enhanced atmospheric oxygen outflow on Earth and Mars driven by a corotating interaction region". J. Geophys. Res. 117 (A16): 3208. Bibcode:2012JGRA..11703208W. doi:10.1029/2011JA017340. 
  17. ↑ Egedal, J., et al. (2012). "Large-scale electron acceleration by parallel electric fields during magnetic reconnection". Nature Phys. Bibcode:2012NatPh...8..321E. doi:10.1038/nphys2249. 
  18. ↑ André, M. and C.M. Cully (2 2012). "Low-energy ions: A previously hidden solar system particle population, in press,". Geophys. Res. Lett. 39 (3). Bibcode:2012GeoRL..3903101A. doi:10.1029/2011GL050242. 
  19. ↑ Shay, M.A., et al. (2011). "Super-Alfvénic Propagation of Substorm Reconnection Signature and Poynting Flux". Physical Review Letters 107 (6): 065001. arXiv:1104.0922. Bibcode:2011PhRvL.107f5001S. doi:10.1103/PhysRevLett.107.065001. 
  20. ↑ Turner, A.J. et al. (2011). "Nonaxisymmetric Anisotropy of Solar Wind Turbulence". Physical Review Letters 107 (9): 095002. arXiv:1106.2023. Bibcode:2011PhRvL.107i5002T. doi:10.1103/PhysRevLett.107.095002. 
  21. ↑ 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. 
  22. ↑ 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. 
  23. ↑ 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. 
  24. ↑ Sahraoui, F. et al. (2010). "Three dimensional anisotropic k spectra of turbulence at subproton scales in the solar wind". Physical Review Letters 105 (13): 131101. Bibcode:2010PhRvL.105m1101S. doi:10.1103/PhysRevLett.105.131101. 
  25. ↑ Masson, A., et al. (2011), "A decade revealing the Sun-Earth connection in three dimensions", Eos, Transactions, American Geophysical Union 92 (1): 4, Bibcode:2011EOSTr..92Q...4M, doi:10.1029/2011EO010007 
  26. ↑ Kistler, L.M. et al. (2010). "Cusp as a source for oxygen in the plasma sheet during geomagnetic storms". J. Geophys. Res. 115: A03209. Bibcode:2010JGRA..11503209K. doi:10.1029/2009JA014838. 
  27. ↑ Yuan, Z. et al. (2010). "Link between EMIC waves in a plasmaspheric plume and a detached sub-auroral proton arc with observations of Cluster and IMAGE satellites". Geophys. Res. Lett. 37 (7): L07108. Bibcode:2010GeoRL..3707108Y. doi:10.1029/2010GL042711. 
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  33. ↑ Dandouras, I. et al. (2009). "Magnetosphere response to the 2005 and 2006 extreme solar events as observed by the Cluster and Double Star spacecraft". Adv. Space Res. 43 (23): 618–623. Bibcode:2009AdSpR..43..618D. doi:10.1016/j.asr.2008.10.015. 
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  37. ↑ Kronberg, E. et al. (2008). "Comparison of periodic substorms at Jupiter and Earth". J. Geophys. Res. 113: A04212. Bibcode:2008JGRA..11304212K. doi:10.1029/2007JA012880. 
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  44. ↑ Phan, T. et al. (2007). "Evidence for an Elongated (>60 Ion Skin Depths) Electron Diffusion Region during Fast Magnetic Reconnection". Physical Review Letters 99 (25): 255002. Bibcode:2007PhRvL..99y5002P. doi:10.1103/PhysRevLett.99.255002. 
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  47. ↑ Rosenqvist, L.et al. (2007). "An unusual giant spiral arc in the polar cap region during the northward phase of a Coronal Mass Ejection". Ann. Geophys. 25 (2): 507–517. Bibcode:2007AnGeo..25..507R. doi:10.5194/angeo-25-507-2007. 
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  50. ↑ Förster, M. et al. (2007). "High-latitude plasma convection from Cluster EDI: variances and solar wind correlations". Ann. Geophys. 25 (7): 1691–1707. Bibcode:2007AnGeo..25.1691F. doi:10.5194/angeo-25-1691-2007. 
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  60. ↑ Nykyri,K. et al. (2006). "Cluster observations of reconnection due to the Kelvin-Helmholtz instability at the dawnside magnetospheric flank". Ann. Geophys. 24 (10): 2619–2643. Bibcode:2006AnGeo..24.2619N. doi:10.5194/angeo-24-2619-2006. 
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  62. ↑ Darrouzet, F. et al. (2006). "Analysis of plasmaspheric plumes: CLUSTER and IMAGE observations". Ann. Geophys. 24 (6): 1737–1758. Bibcode:2006AnGeo..24.1737D. doi:10.5194/angeo-24-1737-2006. 
  63. ↑ Marchaudon, A. et al. (2005). "Simultaneous Double Star and Cluster FTEs observations on the dawnside flank of the magnetosphere". Ann. Geophys. 23 (8): 2877–2887. Bibcode:2005AnGeo..23.2877M. doi:10.5194/angeo-23-2877-2005. 
  64. ↑ Cao, J.B. et al. (2006). "Joint observations by Cluster satellites of bursty bulk flows in the magnetotail". J. Geophys. Res. 111: A04206. Bibcode:2006JGRA..11104206C. doi:10.1029/2005JA011322. 
  65. ↑ Xiao, C.J. et al. (2006). "In situ evidence for the structure of the magnetic null in a 3D reconnection event in the Earth's magnetotail". Nature Phys. 2 (7): 478–483. arXiv:physics/0606014. Bibcode:2006NatPh...2..478X. doi:10.1038/nphys342. 
  66. ↑ Parks, G. et al. (2006). "Larmor radius size density holes discovered in the solar wind upstream of Earth's bow shock". Phys. Plasmas 13: 050701. Bibcode:2006PhPl...13e0701P. doi:10.1063/1.2201056. 
  67. ↑ Mozer, F. et al. (2005). "Spatial gradients in the plasmasphere from Cluster". Geophys. Res. Lett. 32 (24): L24102. Bibcode:2005GeoRL..3224102M. doi:10.1029/2005GL024092. 
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