Space Plasma Physics

Since their dual launches in July and August 2000, ESA's four Cluster spacecraft have been flying in formation around the Earth, sending back the first detailed, three-dimensional information about the magnetosphere and its interaction with the solar wind.

This unique examination of the magnetic bubble that surrounds our planet is about to be enhanced still further as the result of Double Star, a groundbreaking collaboration involving ESA and the Chinese National Space Administration (CNSA).

The Double Star programme involves the launches of two satellites. The first was placed in an equatorial orbit (570 x 78970 km) on 29 December 2003 and the second was placed into a polar orbit (690 x 38230 km) on 25 July 2004 - each carrying experiments provided by European and Chinese institutes. This will enable scientists to analyze data sent back simultaneously from no fewer than six spacecraft, each located in a different region of near-Earth space. The simultaneous, six-point study should provide new insights into the mysterious mechanisms that trigger magnetic storms and brilliant auroral displays in polar skies.

ESA pages of Cluster
ESA pages of Double Star

Double Star and Cluster orbits in August 2004
(copyright: ESA)

One hundred and thirty space scientists from around the globe gathered to discuss the most recent scientific achievements, the goals of the Cluster mission, and chart out the next phase of the mission.
Cluster is a four spacecraft mission, carrying 11 identical instruments on each spacecraft, designed to study the Earth's magnetic field or "magnetosphere" and the plasma environment in the near Earth region. This mission, in orbit since the summer of 2000, allows, for the first time, three-dimensional measurements of key regions of space surrounding the Earth. Because of the great success of the mission, an extension to at least 2007 is being discussed.

ESA Report

ESA's four Cluster spacecraft have made a remarkable set of observations that has led to a breakthrough in understanding the origin of a peculiar and puzzling type of aurora.

( ESA press release 31/2003)

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Our climate has shown considerable natural variability over the course of centuries and millennia. Between the 9th and 14th century, our planet experienced the Mediaeval Warm Period. During this time, the global temperature average was higher than at present by about 1°C. Tree-ring data show that this was not a result of a natural rise in carbon dioxide, so the Sun's variability is the main suspect.

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Magnetic Reconnection is a process that converts magnetic energy into kinetic energy of plasma jets. It also provides access of one cosmic plasma to another one, e. g. at the interface of a stellar wind or accretion disk with the magnetic field of a neighbouring star. Such a situation exists between the solar wind and the Earth's magnetosphere. Reconnection of the respective magnetic fields does not only allow entry of solar wind plasma into the Earth's field, but by stretching it into the long magnetic tail it pumps energy into the Earth's system and is so responsible for magnetic storms, aurora, radiation belts and their variations, in short, for the space weather.

( press release)

T.D. Phan et al, Nature 404, 848-850 (2000)