Cluster II (spacecraft)

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Cluster II
The Cluster II constellation.
Artist's impression of the Cluster constellation.
Mission type Magnetospheric research
Operator ESA with NASA collaboration
COSPAR ID FM6 (SALSA): 2000-041A
FM7 (SAMBA): 2000-041B
FM5 (RUMBA): 2000-045A
FM8 (TANGO): 2000-045B
SATCAT no. FM6 (SALSA): 26410
FM7 (SAMBA): 26411
FM5 (RUMBA): 26463
FM8 (TANGO): 26464
Mission duration planned: 5 years
elapsed: 16 years, 6 months and 3 days
Spacecraft properties
Manufacturer Astrium[1]
Launch mass 1,200 kg (2,600 lb)[1]
Dry mass 550 kg (1,210 lb)[1]
Payload mass 71 kg (157 lb)[1]
Dimensions 2.9 m × 1.3 m (9.5 ft × 4.3 ft)[1]
Power 224 watts[1]
Start of mission
Launch date FM6: 16 July 2000, 12:39 UTC (2000-07-16UTC12:39Z)
FM7: 16 July 2000, 12:39 UTC (2000-07-16UTC12:39Z)
FM5: 09 August 2000, 11:13 UTC (2000-08-09UTC11:13Z)
FM8: 09 August 2000, 11:13 UTC (2000-08-09UTC11:13Z)
Rocket Soyuz-U/Fregat
Launch site Baikonur 31/6
Contractor Starsem
Orbital parameters
Reference system Geocentric
Regime Elliptical Orbit
Perigee FM6: 16,118 km (10,015 mi)
FM7: 16,157 km (10,039 mi)
FM5: 16,022 km (9,956 mi)
FM8: 12,902 km (8,017 mi)
Apogee FM6: 116,740 km (72,540 mi)
FM7: 116,654 km (72,485 mi)
FM5: 116,786 km (72,567 mi)
FM8: 119,952 km (74,535 mi)
Inclination FM6: 135 degrees
FM7: 135 degrees
FM5: 138 degrees
FM8: 134 degrees
Period FM6: 3259 minutes
FM7: 3257 minutes
FM5: 3257 minutes
FM8: 3258 minutes
Epoch 13 March 2014, 11:15:07 UTC

Cluster II mission insignia
ESA solar system insignia for the Cluster II mission

Cluster II[2] is a space mission of the European Space Agency, with NASA participation, to study the Earth's magnetosphere over the course of nearly two solar cycles. The mission is composed of four identical spacecraft flying in a tetrahedral formation. As 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 2016. China National Space Administration/ESA Double Star mission operated alongside Cluster II from 2004 to 2007.

Mission overview[edit]

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.

The 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 the Cluster Active Archive.


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 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 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.[3] Ray Cotton, from the United Kingdom, won the competition with the names Rumba, Tango, Salsa and Samba.[4] Ray's town of residence, Bristol, was awarded with scale models of the satellites in recognition of the winning entry,[5][6] 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 2018.[7]

Scientific objectives[edit]

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[edit]

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 High time resolution measurements of both electric and magnetic fields in selected frequency bands from 25 Hz to 577 kHz. It provides a unique new capability to perform Very-long-baseline interferometry (VLBI) measurements. Properties of natural plasma waves (e.g. auroral kilometric radiation) in the Earth magnetosphere and its vicinity including: source location and size and propagation.
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[edit]

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[8] 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: Echo of this story on CNN:

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:

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:

"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[edit]

Latest scientific highlight[edit]

The interaction between Earth’s magnetic field and the solar wind results in the formation of a collisionless bow shock 60,000–100,000 km upstream of our planet, as long as the solar wind fast magnetosonic Mach number exceeds unity. A recent paper published in Nature Communications[9] by Dr. Lugaz and co-authors (University of New Hampshire, USA) presents one of those extremely rare instances, when the solar wind Mach number reached steady values below 1 for several hours on 17 January 2013. Simultaneous measurements by more than ten spacecraft, including Cluster, in the near-Earth environment reveal the evanescence of the bow shock, the sunward motion of the magnetopause and the extremely rapid and intense loss of electrons in the outer radiation belt. This study allows to directly observe the state of the inner magnetosphere, including the radiation belts during a type of solar wind-magnetosphere coupling which is unusual for planets in our solar system but may be common for close-in extrasolar planets.


Full story

The ESA Cluster mission has enabled to find the first direct evidence of cross-scale energy transport between fluid and ion-scale waves, explaining why Earth's magnetic environment is so hot. A Nature Physics paper reveals. The Earth's internal magnetic field creates a giant protective bubble called the magnetosphere, necessary for life to develop. This magnetic bubble helps deflecting more than 99% of the incoming solar wind expelled by the Sun. Due to this interaction, the magnetosphere has a bullet-like shape (see left panel of Figure 1). At its border, the magnetopause, the matter, called plasma, is 50 times hotter inside the Earth's magnetic environment than just outside; a problem that has puzzled scientists since the beginning of the space age. Why is Earth's environment so hot? How plasma gets heated in a medium where no particles collides? One of the few physical processes enabling solar wind plasma to enter the magnetosphere is called the Kelvin-Helmholtz instability. This instability is ubiquitous in space and on Earth. Such K-H waves have been detected in various media including the surface of oceans, in clouds (see bottom right panel of Image 1), in the solar corona (see top right panel) or in the atmosphere of giant planets. Kelvin–Helmholtz (K-H) waves can form at Earth's magnetopause, mainly due to the velocity difference between the plasma flowing outside at higher speed than inside the magnetosphere. Back in 2004, the multi-spacecraft Cluster mission revealed that these waves can roll-up, turning into giant vortices of about 36,000 km size, i.e. about 6 times the Earth's radius (Hasegawa et al., 2004). A new article, published in Nature Physics this month, presents a detailed study of small-scale (ion-scale) wave packets captured by Cluster within such a macroscopic (fluid-scale) Kelvin-Helmholtz vortex. This study reveals for the first time that these wave packets in the eye of the vortex are magnetosonic waves with sufficient energy to account for the observed level of ion heating. In other words, these waves can heat the cooler ions of magnetosheath origin; magnetosheath is the boundary layer located just outside the magnetopause. These observations may be evidence for cross-scale energy transport in space plasmas. It may have universal consequences in understanding the energy transport from fluid to ion scales, and can play a role in a variety of plasma systems with a velocity shear.

Full story

Colorful auroras are due to a phenomenon called magnetic substorms. A substorm is a major reconfiguration of the Earth's magnetic field on the nightside. During substorms, oppositely directed magnetic field lines reconnect in the distant magnetotail. The relaxation of the magnetic tension of the stretched field lines converts the stored magnetic energy into plasma kinetic energy and heat. The plasma is accelerated earthward in short duration bursty bulk flows (BBFs). The BBFs are the most prominent means to carry mass and energy from the tail toward the near-Earth region. BBFs are often accompanied by magnetic field dipolarization, at their front, as detected by the multi-spacecraft Cluster mission [e.g., Nakamura et al., 2002]. Observationally, they are seen by satellites as a sharp increase in the vertical-to-the-current sheet component (Bz), usually preceded by a transient decrease in Bz. These asymmetric bipolar variations in the z component of the magnetic field are referred to as dipolarization fronts (DFs). DFs velocities can be estimated by multi-spacecraft observations. Such velocities have been estimated since 2002 by the first multi-spacecraft magnetospheric mission, the ESA Cluster mission, at around 19 Earth radii or RE (around 115,000 km from Earth), i.e. in the outer magnetotail region. But how these velocities evolve as BBF propagate towards Earth? In a recent study published by Schmid et al. (2016),[11] these multi-spacecraft DFs observations have been compared with other multi-spacecraft DFs observations. These DFs velocities have been estimated in 2015 by the NASA Magnetospheric Multiscale Mission (MMS) mission below 12 RE distance from Earth, i.e. in the inner magnetotail region, and by Cluster at distances around 20 RE measured in 2003. As expected most of the BBFs observed are Earthward propagated, but about 25% of DFs are tailward propagating. Thanks to the DFs measurements at two locations in the tail, Schmid et al. interpret that these tailward propagating events are the result of DFs rebound (bouncing) near Earth where the magnetic field is almost like a dipole. Another interesting feature found is that the larger DF velocities correspond to higher values of Bz directly ahead of the DFs. This behavior is observed by both Cluster and MMS despite their very different locations. Schmid et al. (2016) interpret the higher Bz to a local snow plow like phenomenon resulting from a higher DF velocity and thus a higher magnetic flux pileup ahead of the DF. Coordinated BBF measurements by Cluster and MMS, this time simultaneously, are planned in August 2016.

A complementary result on dipolarization front ahead of a BBF was recently published in the literature by Zhonghua Yao (University College London, UK) and co-authors.[12] The DF in front of BBF is thought to carry an intense current, sufficient to modify the large-scale near-Earth magnetotail current system which eventually leads to colourful northern lights. However, the physical mechanism of the current generation associated with DFs is poorly understood due to the lack of measurements. It indeed takes only a few seconds for a DF to travel past a spacecraft. For the first time, a sufficient number of 3D distribution functions on the DF timescale have been captured, thanks to Cluster measurements with a temporal cadence of 0.25s. The observations clearly show details of plasma sub-structure within the DF, including the presence of field-aligned electron beams. These results imply that the nature of the DF current system needs to be revisited by complementary high resolution particle measurements, such as the ones soon expected with MMS.















Selected publications[edit]

All 2937 publications related to the Cluster and the Double Star missions (count as of 31 January 2017) can be found on the publication section of the ESA Cluster mission website. Among these publications, 2465 are refereed publications, 340 proceedings, 107 PhDs and 25 other type of theses.

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  7. ^ "Two-Year extensions confirmed for ESA's science missions."ESA Science and Technology. Retrieved: 22 November 2016.
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  12. ^ Yao, Z., A. N. Fazakerley, A. Varsani, I. J. Rae, C. J. Owen; et al. (2016). "Substructures within a dipolarization front revealed by high-temporal resolution Cluster observations". J. Geophys. Res. Space Phys. 121: 5185–5202. doi:10.1002/2015JA022238. 
  13. ^ Lee, S.H. , H. Zhang, Q.-G. Zong, A. Otto, H. Rème, E. Liebert (2016). "A statistical study of plasmaspheric plumes and ionospheric outflows observed at the dayside magnetopause". J. Geophys. Res. Space Phys. 121: 492–506. doi:10.1002/2015JA021540. 
  14. ^ Zhang, B. , O. J. Brambles, W. Lotko, J.E. Ouellette, J.G. Lyon (2016). "The role of ionospheric O+ outflow in the generation of earthward propagating plasmoids". J. Geophys. Res. Space Phys. 121: 1425–1435. doi:10.1002/2015JA021667. 
  15. ^ Wang, R., Q. Lu, R. Nakamura, C. Huang, A. Du, F. Guo, W. Teh, M. Wu, S. Lu, S. Wang (2015). "Coalescence of magnetic flux ropes in the ion diffusion region of magnetic reconnection". Nat. Phys. 12: 263–267. Bibcode:2016NatPh..12..263W. doi:10.1038/nphys3578. 
  16. ^ Balikhin, M.A., Y.Y. Shprits, S.N. Walker, L. Chen, N. Cornilleau-Wehrlin, I. Dandouras, O. Santolik, C. Carr, K.H. Yearby, B. Weiss (2015). "Observations of Discrete Harmonics Emerging From Equatorial Noise". Nat. Commun. 6: 7703. Bibcode:2015NatCo...6E7703B. doi:10.1038/ncomms8703. 
  17. ^ Dunlop, M.W., J.-Y. Yang, Y.-Y. Yang, C. Xiong, H. Lühr, Y. V. Bogdanova, C. Shen, N. Olsen, Q.-H. Zhang, J.-B. Cao, H.-S. Fu, W.-L. Liu, C. M. Carr, P. Ritter, A. Masson, and R. Haagmans (2015). "Simultaneous field-aligned currents at Swarm and Cluster satellites". Geophys. Res. Lett. 42 (10): 3683–3691. Bibcode:2015GeoRL..42.3683D. doi:10.1002/2015GL063738. 
  18. ^ Russell, A. J. B.; Karlsson, T. & Wright, A. N. (2015). "Magnetospheric signatures of ionospheric density cavities observed by Cluster". J. Geophys. Res. Space Phys. 120: 1876–1887. Bibcode:2015JGRA..120.1876R. doi:10.1002/2014JA020937. 
  19. ^ Fear, R.C., S.E. Milan, R. Maggiolo, A.N. Fazakerley, I. Dandouras, and S.B. Mende (2014). "Direct observation of closed magnetic flux trapped in the high latitude magnetosphere". Science. 346 (6216): 1506–1510. Bibcode:2014Sci...346.1506F. doi:10.1126/science.1257377. 
  20. ^ Kozyra; et al. (2014). "Solar filament impact on 21 January 2005: Geospace consequences". J. Geophys. Res. Space Physics. 119: 2169–9402. Bibcode:2014JGRA..119.5401K. doi:10.1002/2013JA019748. 
  21. ^ Graham, D.B.; Yu. V. Khotyaintsev; A. Vaivads; M. Andre & A. N. Fazakerley (2014). "Electron Dynamics in the Diffusion Region of Asymmetric Magnetic Reconnection". Phys. Rev. Lett. 112: 215004. Bibcode:2014PhRvL.112u5004G. doi:10.1103/PhysRevLett.112.215004. 
  22. ^ Tsyganenko, N. (2014). "Data-based modeling of the geomagnetosphere with an IMF-dependent magnetopause". J. Geophys. Res. Space Phys. 119: 335–354. Bibcode:2014JGRA..119..335T. doi:10.1002/2013JA019346. 
  23. ^ Décréau, P.M.E.; et al. (2013). "Remote sensing of a NTC radio source from a Cluster tilted spacecraft pair" (PDF). Ann. Geophys. 31: 2097–2121. Bibcode:2013AnGeo..31.2097D. doi:10.5194/angeo-31-2097-2013. 
  24. ^ 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. 
  25. ^ 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. 
  26. ^ 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. 
  27. ^ 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. 
  28. ^ 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. 
  29. ^ Perri, S.; et al. (2012). "Detection of small scale structures in the dissipation regime of solar wind turbulence". Phys. Rev. Lett. 109 (19): 191101. Bibcode:2012PhRvL.109s1101P. doi:10.1103/PhysRevLett.109.191101. PMID 23215371. 
  30. ^ 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. 
  31. ^ 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. PMID 23006181. 
  32. ^ Nykyri, K.; et al. (2012). "On the origin of high-energy particles in the cusp diamagnetic cavity". Journal of Atmospheric and Solar-Terrestrial Physics. 87–88 (Special Issue on Physical Process in the Cusp: Plasma Transport and Energization): 70–81. Bibcode:2012JASTP..87...70N. doi:10.1016/j.jastp.2011.08.012. 
  33. ^ 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. 
  34. ^ Egedal, J.; et al. (2012). "Large-scale electron acceleration by parallel electric fields during magnetic reconnection". Nature Phys. 8: 321–324. Bibcode:2012NatPh...8..321E. doi:10.1038/nphys2249. 
  35. ^ André, M.; C.M. Cully (February 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. 
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  37. ^ Turner, A.J.; et al. (2011). "Nonaxisymmetric Anisotropy of Solar Wind Turbulence". Physical Review Letters. 107 (9): 095002. arXiv:1106.2023Freely accessible. Bibcode:2011PhRvL.107i5002T. doi:10.1103/PhysRevLett.107.095002. 
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