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Fact Sheet


 Fast Facts


Launch date: 16-Jul-2000 12:39 UT and 09-Aug-2000 11:13 UT
Mission end: 31 December 2022
Launch vehicle: 2 Russian Soyuz launchers, each with a Fregat upper stage
Launch mass: 4800 kg
Mission phase: Operational
Orbit: Elliptical polar orbit, period: 57 hours
Perigee: 19 000 km, apogee: 119 000 km
Achievements: The four Cluster spacecraft are providing a detailed three-dimensional map of the magnetosphere, with surprising results.

Cluster is currently investigating the Earth's magnetic environment and its interaction with the solar wind in three dimensions. Science output from Cluster greatly advances our knowledge of space plasma physics, space weather and the Sun-Earth connection and has been key in improving the modeling of the magnetosphere and understanding its various physical processes.

Mission Objectives

Cluster II is part of an international collaboration to investigate the physical connection between the Sun and Earth. Flying in a tetrahedral (triangular pyramid) formation, the four spacecraft collect the most detailed data yet on small-scale changes in near-Earth space and the interaction between the charged particles of the solar wind and Earth's atmosphere. This enables scientists to build a three-dimensional model of the magnetosphere and to better understand the processes taking place inside it.

Mission Name

The name Cluster was chosen because of the way the four spacecraft will fly in a group around the Earth. When studies demonstrated that it would be possible to reuse some parts and to fly four spacecraft which were almost identical to those which were lost, the replacement mission was named Cluster II.


Diameter: 2.9 m
Height: 1.3 m
Mass: 1200 kg
(of which) Propellant:

650 kg

(of which) Scientific payload: 71 kg
Solar array power: 224 W
Spin rate: 15 rpm
Operational lifetime: 5 years (nominal)



Each of the four spacecraft carries an identical set of 11 instruments to investigate charged particles, electrical and magnetic fields. These were built by European and American instrument teams led by Principal Investigators.

FGM Fluxgate Magnetometer
EDI Electron Drift Instrument
ASPOC Active Spacecraft Potential Control experiment
STAFF Spatio-Temporal Analysis of Field Fluctuation experiment
EFW Electric Field and Wave experiment
DWP Digital Wave Processing experiment
WHISPER Waves of High frequency and Sounder for Probing of Electron density by Relaxation experiment
WBD Wide Band Data instrument
PEACE Plasma Electron And Current Experiment
CIS Cluster Ion Spectrometry experiment>
RAPID Research with Adaptive Particle Imaging Detectors
WEC Wave Experiment Consortium (DWP, EFW, STAFF, WBD, and WHISPER)



Elliptical polar orbit, 19 000 to 119 000 km, 57 hour period.

Operations Centre

  • Spacecraft operations centre: European Space Operations Centre (ESOC), Germany.
  • Ground station: Villafranca and Maspalomas, Spain.
  • Science operations centre: Joint Science Operations Centre at Rutherford Appleton Laboratory, Didcot, UK.
Last Update: 3 November 2020
18-Jul-2024 10:23 UT

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