Cluster

The mission

Cluster, a four spacecraft flotilla of magnetospheric research spacecaft, and the solar observatory SOHO, are the spacecraft of the first European Space Agency 'Cornerstone' mission. The original four Cluster spacecraft were destroyed in a launch accident in 1996. A new set of four spacecraft (Cluster II) was launched on 16 July 2000 and 09 August 2000 by Soyuz-Fregat rockets (the first ESA spacecraft to be launched by Russian rockets). After successful completion of its first two years of operation, the mission has been extended to December 2005, allowing a larger range of spatial scales to be explored. (see below)

Science objectives

artists impression of cluster in orbit                                                                          The Cluster mission uses four spacecraft flying in a group to explore the Earth's magnetosphere. The magnetosphere is a huge region of space surrounding the Earth where the Earth's magnetic field can be detected. Outside the magnetosphere is a fast flowing plasma from the Sun, the solar wind. Inside the magnetosphere we find plasma from the solar wind as well as the Earth's ionosphere. Furthemore, we know that large amounts of energy are transferred from the solar wind to the magnetosphere. The energy is frequently released in dramatic processes, such as substorms, that generate energetic radiation belt particles, disturb the Earths' magnetic field at the surface and power the Northern Lights.

Earlier spacecraft missions have shown us that these large scale effects are due to processes that occur on much smaller scales (10's to 1000's of km). In order to test competing theories, it is necessary to make measurements at several points simultaneously. This should be done at several different spatial separations. Therefore Cluster has four spacecraft, which can change their distances from one another. Also the Cluster orbit is designed to visit regions in the magnetosphere where solar wind plasma may enter and where clues to the energy release processes are most likely to be found.

MSSL are Principal Investigator institution for the PEACE electron spectrometer team, leading a team of scientific collaborators. MSSL, together with RAL and NDRE  built ten PEACE Instruments for flight, four Flight Instruments and a Flight Spare for each of Cluster and Cluster II (and engineering test models). MSSL fully calibrated all these ten instruments. A PEACE Operations Team at MSSL currently controls the instruments, processes their data and carries out in-flight calibration work.

Further Information

The Cluster homepage at ESA

The Cluster PEACE homepage at MSSL

17 September 2003
Andrew Fazakerley
anf@mssl.ucl.ac.uk