Artist's impression of the four Cluster spacecraft flying through the thin layer of Earth's bow shock.
Image credits: SA/AOES Medialab.
ESA's Cluster satellites have discovered that cosmic particle accelerators are more efficient than previously thought. The discovery has revealed the initial stages of acceleration for the first time, a process that could apply across the Universe.
On 9 January 2005, Cluster's four satellites passed through a magnetic shock high above Earth. The spinning craft were aligned almost perfectly with the magnetic field, allowing them to sample what was happening to electrons on very short timescales of 250 milliseconds or less.
The measurements showed that the electrons rose sharply in temperature, which established conditions favourable to larger scale acceleration. (read more)