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
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
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