Cluster II (spacecraft)
Cluster II 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. its mission has been extended until the end of 2020 with a likely extension lasting until 2022. 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 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 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 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 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 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 .
History
The Cluster mission was proposed to ESA in 1982 and approved in 1986, along with the Solar and Heliospheric Observatory, 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, 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 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. Ray Cotton, from the United Kingdom, won the competition 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 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 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 2020.
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 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 and electric and magnetic fields in the region.
Instrumentation on each Cluster satellite
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 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/jump.cfm?oid=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.
Awards
Cluster team awards- 2019
- 2015 ESA 15th anniversary award
- 2013 ESA team award
- 2010
- 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
- 2020 Daniel Graham was awarded the
- 2019 Margaret Kivelson, Cluster FGM CoI,
- 2018 Hermann Opgenoorth, former Cluster Ground Based Working Group lead, was awarded the
- 2016 Stephen Fuselier, Cluster CIS CoI,
- 2016 Mike Hapgood, Cluster mission scientific operations expert was
- 2014 Rumi Nakamura, Cluster CIS/EDI/FGM CoI,
- 2013 Mike Hapgood, Cluster JSOC project scientist
- 2013 Steve Milan, Cluster Ground based representative of the Cluster mission
- 2012 Andrew Fazakerley, Cluster and Double Star PI,
- 2012 Zuyin Pu, RAPID/CIS/FGM CoI,
- 2012 Jolene Pickett, a Cluster WBD PI,
- 2012 Jonathan Eastwood, FGM Co-I,
- 2008 Andre Balogh, Cluster FGM PI,
- 2006 Steve Schwartz, Cluster UK data system scientist and PEACE co-I,
Discoveries and mission milestones
2020
- April 20 -
- April 16 -
- March 19 -
- February 27 -
2019
- December 23 -
- November 18 -
- October 10 -
- August 27 -
- August 20 -
- August 5 -
- May 1 -
- March 4 -
- February 27 -
- February 13 -
- January 14 -
2018
- November 28 –
- November 8 -
- September 30 -
- August 8 -
- June 20 –
- May 21 –
- April 24 –
- March 29 –
- February 8 –
- January 29 –
- January 22 –
2017
- December 11, 2017 –
- December 6, 2017 –
- October 30, 2017 –
- September 18, 2017 –
- August 28, 2017 –
- August 1, 2017 –
- June 16, 2017 –
- April 10, 2017 -
- April 7, 2017 –
- March 23, 2017 –
- February 18, 2017 –
2016
- October 3, 2016 –
- September 6, 2016 –
- July 20, 2016 –
- July 8 –
- July 7 –
- June 11 –
- May 11 –
- March 21 –
- February 29 –
- January 11 –
2015
- December 7 -
- October 22 -
- September 3 -
- August 22 -
- July 14 -
- July 1 -
- April 9 -
- March 25 -
- February 19 -
- February 16 -
- January 16 –
2014
- December 18 –
- November 20 -
- September 4 -
- August 28 –
- July 1 -
- June 15 -
- May 28 -
- May 7 -
- March 15 -
- January 13 -
2013
- November 26 -
- November 15 –
- September 20 -
- September 10 –
- July 18 -
- July 2 -
- May 2 -
- April 15 -
- April 10 –
2012
- December 18 –
- October 24 -
- August 1 –
- July 2 -
- June 6 –
- March 7 -
- February 27 -
- February 23 -
- January 26 -
- January 24 –
2011
- November 16 –
- September 6 –
- August 31 -
- July 5–10 -
- July 4 –
- June 30 -
- March 21 -
- February 5 –
- January 7 -
2010
- November 22 -
- October 4 –
- September 1 -
- July 26 -
- July 16 -
- July 8 -
- June 3 –
- April 24 -
- March 11 -
- January 20 -
2009
- October 7 -
- July 16 –
- June 18 -
- April 29 -
- March 25 -
- February 9 -
- January 14 –
2008
- December 15 -
- December 5 -
- October 17 -
- August 27 -
- August 11 -
- June 27 -
- June 9 -
- March 7 -
- January 23 -
2007
- December 6 -
- November 21 -
- November 9 -
- October 22 -
- September 11 -
- July 26 -
- June 29 -
- June 21 -
- May 11 -
- April 12 -
- March 26 -
- March 12 -
- February 9 -
2006
- December 29 -
- December 6 -
- November 13 -
- October 5 -
- August 24 -
- July 18 -
- June 20 -
- May 19 -
- March 30 -
- February 24 -
- February 1 -
- January 11 -
2005
- December 22 -
- September 21 -
- August 10 -
- July 28 -
- July 14 -
- April 28 -
- February 18 -
- February 4 -
2004
- December 12 -
- November 24
- September 17 -
- August 12 -
- June 23 -
- May 13 -
- April 5 -
2003-2001
- 2003.12.03 -
- 2003.06.29 -
- 2003.05.20 -
- 2003.01.29 -
- 2003.01.28 -
- 2002.12.29 -
- 2002.10.01 -
- 2001.12.11 -
- 2001.10.31 -
- 2001.10.09 -
- 2001.02.01 –
Selected publications