Space scientists around the world are today celebrating the first anniversary of the European Space Agency's revolutionary Cluster mission to explore near-Earth space and study the interaction between the Sun and Earth.
The magnetosphere - a natural protective bubble
Cluster
The fluctuating fortunes of the magnetic field surrounding Earth are monitored by the Cluster flotilla
Cluster has also provided the first confirmation of waves along the magnetopause - the outer limit of Earth's magnetic field. Until now, these plasma waves have only existed in computer simulations, but the Cluster spacecraft have surfed these waves and confirmed their existence. The speed of the waves has been estimated at around 70 km/s - equivalent to travelling from London to Paris in 4.5 seconds. One of the real surprises concerned the polar cusps - 'windows' above the northern and southern polar regions where the particles from the solar wind can penetrate the magnetic shield. These cusps rapidly shift position due to gusts in the solar wind. The Cluster quartet has shown that they pivot through space at between 10 and 30 km/s - the first time this motion has been directly measured by spacecraft.
In June 2001 Cluster began to explore the magnetotail - the region where storms of high energy particles are generated
The best is yet to come...
The latest chapter in Cluster's exciting exploration began in June, when ESA's intrepid flotilla began to explore the elongated magnetotail which stretches far beyond the Moon. During the next few months, Cluster will cast new light on this region where storms of high energy particles are generated. When these particles arrive at the Earth, they can cause intense auroras on the nightside of the Earth. A less attractive consequence is their ability to cause power cuts, damage satellites and disrupt communications.
http://www.esa.int/esaCP/ESAN3D0VMOC_index_0.html