New launch date set for Chinese/ESA Double Star mission (Forwarded)

ESA News
http://www.esa.int

26 December 2003

New launch date set for Chinese/ESA mission

The Chinese National Space Agency (CNSA) will now launch the first of two
scientific satellites known as Double Star on 29 December at 19:06 CET [1806
UTC] (30 December, 03:06 local time). The mission was due to be launched
tomorrow, 27 December, but a minor fault on the launch vehicle caused this
slight delay. ESA is contributing to this Double Star mission by providing eight
on-board scientific instruments.

Double Star follows the footsteps of ESA's Cluster mission and will study
closely the interaction between the 'solar wind' and the Earth's magnetic field.
In 1997, the CNSA invited ESA to participate in Double Star, a two-satellite
mission to study the Earth's magnetic field, from a perspective which is
different from that of Cluster but complementary to it.

Cluster and Double Star spacecraft will co-ordinate their investigations and
help us gain a much better understanding of the processes taking place above Earth.

Some of these phenomena are spectacularly beautiful, such as the polar aurorae,
but others, like the magnetic storms, can have serious effects on human
activities -- from power cuts to damaged satellites and communication breakdowns.

The positions and orbits of the two Double Star satellites have been carefully
chosen to allow the study of the magnetosphere on a larger scale than that
possible with Cluster alone.

A typical example of how both missions will co-operate is the study of the
magnetic substorms producing the bright aurorae. Double Star and Cluster
together will address the fundamental question where these substorms start.

The Cluster satellites are in a high orbit, about one third of the distance to
the Moon, where the mechanisms causing these substorms are thought to begin. The
spacecraft are very close to each other, only a few hundred kilometres between
them, allowing us to observe small regions in a great detail.

However, some scientists suggested that these mechanisms might begin closer to
the Earth, so this is why Double Star will be placed in lower orbits.

The four Cluster spacecraft are currently passing in and out of the
magnetosphere, visiting regions where the interaction with the solar wind is
especially important, such as the 'polar cusps' and the 'magnetotail'.

The polar cusps are funnel-like openings in the magnetosphere at the poles, and
are the 'doors' used by electrically charged particles from the solar wind to
descend into Earth's upper atmosphere.

The magnetotail is the part of the magnetosphere pushed in the direction of the
solar wind -- shaped like a giant windsock and stretching at least two million
kilometres into space on the night side of the Earth.

These regions are difficult to explore and many mysteries remain but Double Star
and Cluster will eventually help us to understand more about these phenomena.

More about ...

* Double Star overview
http://www.esa.int/esaSC/120381_index_0_m.html
* Cluster overview
http://www.esa.int/esaSC/120383_index_0_m.html

Related articles

* How the Sun affects us on Earth
http://www.esa.int/esaSC/SEML7BS1VED_foryou_0.html
* Cluster's new view of near-Earth space
http://www.esa.int/esaCP/ESA6VTTM5JC_index_0.html
* Surfing and diving in the Earth's magnetosphere, Cluster celebrates one year
of science excellence in orbit
http://www.esa.int/esaCP/ESAN3D0VMOC_index_0.html
* Cluster quartet take a trip down Earth's tail
http://www.esa.int/esaCP/ESA33G2VMOC_index_0.html
* Solar storm blasts Cluster
http://www.esa.int/esaCP/ESAB7E8VTTC_index_0.html
* ESA's Cluster sees 'squashed' magnetosphere
http://www.esa.int/esaSC/SEMGZ8WLDMD_exploring_0.html

IMAGE CAPTIONS:

[Image 1:
http://www.esa.int/export/esaCP/SEMW..._index_1.html]
Double Star satellite in its launch configuration. Double Star's satellite pair
study space weather around the Earth. One satellite circles the Earth's Equator,
the other flies over the poles.

Credits: Chinese National Space Administration

[Image 2:
http://www.esa.int/export/esaCP/SEMW...html#subhead1]
Double Star Programme (DSP). This mission consists of two satellites, the
equatorial satellite DSP-E, following a 550 x 60 000 kilometre orbit, inclined
at 28.5 degrees to the Equator and the polar satellite DSP-P, following a 350 x
25 000 kilometre orbit inclined at 90 degrees to the Equator.

Credits: Chinese National Space Administration

[Image 3:
http://www.esa.int/export/esaCP/SEMW...html#subhead2]
Artist's impression Cluster II.

[Image 4:
http://www.esa.int/export/esaCP/SEMW...html#subhead4]
Double Star logo.

Credits: ESA