SAMPEX / HILT
STEREO / PLASTIC
Double Star - East Meets West in Near-Earth Space
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
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
Artist's impression of Double Star
in orbit around the Earth
Double Star and Cluster orbits in August 2004
Highlights from 8th Cluster Workshop
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
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's Cluster solves auroral puzzle
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)
Linking the Earth's climate with the Sun
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.
Equator-S and Geotail find long sought plasma process
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.
T.D. Phan et al,
Nature 404, 848-850 (2000)
Last update: 2010-06-18 by