Cluster Status Report - November 2005
Operations and Archiving
JSOC and ESOC operations are continuing nominally. Work is progressing for the switch from VILSPA to the Perth ground station starting early 2006. The data return from March 2005 to early September 2005 was above 99.4%.
During the past months the Cluster Active Archive (CAA) team has been working towards the opening of the CAA in autumn 2005. The initial opening for beta testing took place during the Cluster symposium on 23 September 2005 and the official opening will take place on 1 February 2006. The ESTEC team has concentrated on the ingestion software and the user interface and the instrument teams on the delivery of data. More disks were added to the CAA system so that we have currently about 12 Tbytes available space.
Science Highlights
The Cluster-Double Star symposium took place at ESTEC on 19-23 September 2005. This was a special occasion to celebrate the 5th anniversary of Cluster in space and more than 160 scientists from China, Europe, Japan, Russia and Japan participated. Sessions on the latest Cluster and Double Star results and multi-spacecraft analysis tools, as well on future magnetospheric missions in China, Europe, Japan, Russia and USA were organised during the full week symposium. A certificate was distributed to scientists and engineers who had participated in Cluster and special awards were attributed to persons or teams who have made an outstanding contribution to the mission.
The first direct measurement of electric current in the "ring current" has been published in Annales Geophysicae. The ring current is part of the radiation belts that increases dramatically during geomagnetic storms. The curlometer method (measurement of the magnetic field at the four spacecraft and computation of current) was not expected to give good results in the ring current because the spacecraft tetrahedron is greatly deformed. However having the four Cluster satellites at small distances (below 200 km) showed that the current could still be estimated with accuracy.
Two papers were published in Nature in August and September 2005 based on Cluster data. The first one presented the first observations of short-scales-Alfven vortices in the polar cusp. These are produced in turbulent plasma and, although theory predicted their occurrence, they had never been observed in space. The second one presented the changes of the radiation belts during the Oct-Nov 2003 storms. The radiation belts disappeared from their usual location and then reformed much closer to the Earth in a region were high energy particles are usually not found. Combining Cluster and Antarctica data, it was found that an electromagnetic emission called "chorus" was responsible for the acceleration of electrons. Radiation belts can be a hazard to satellites and humans in space and such studies are crucial to understand their formation.