Cluster Status Report - October 2003
Long eclipses (more than 2 hours) were passed successfully in September. ESOC flight dynamics have found that a proper orientation of the tetrahedron and a decrease of the argument of perigee would keep the spacecraft in orbit at least up to the end of 2007.
Science highlights
- The centre of the magnetotail is the place where magnetic reconnection is taking place, producing a highly curved magnetic field. For the first time with Cluster the radius of curvature can be obtained. Using the four spacecraft the gradient of the magnetic field can be measured and then the radius of curvature computed. A paper published in Journal of Geophysical Research by Chinese colleagues has shown that the radius of curvature is changing with the phase of the geomagnetic substorm.
- During a crossing of the magnetopause, the boundary between the solar wind and the Earth magnetosphere, the local shape and magnetic configuration could be reconstituted with the four spacecraft. Spacecraft 3 observed an impermeable magnetopause while spacecraft 1, about 20s later, observed that the reconnection process had opened the magnetopause.
- Chorus is an electromagnetic emission in the acoustic frequency range created by high-energy particles circulating in the radiation belts. The source of chorus is believed to originate in the equatorial plane. Using the four spacecraft, the motion of the chorus source could be followed for the first time during about 20 min. It was shown that the position of the chorus emission oscillates around the equatorial plane with an amplitude of about +/- 2000 km.
The 6th Cluster workshop (3rd of 2003) was organized during the first week of October. The workshop was run with 3 parallel sessions where results from the previous years were presented and new events from this year were discussed. Scientists from the community and RSSD organized and chaired the sessions. For this workshop, 7 sessions where organized that covered the effect of solar activity on the magnetosphere, the bow shock, the magnetopause, the polar cusp, the inner magnetosphere, the plasma wave modes identification and the spatio-temporal fluctuations. Among the new results, the highlights were the first measurement of electric current at the bow shock and the first full view of the elbow of a flux transfer event at the magnetopause.
Operations and Archiving
User access to the nationally funded Cluster Science Data System (CSDS) is now more or less stabilised. The average download by individual users over the last three months was 5 Gbytes/month .
The Cluster Active archive user requirements document has been discussed with the PIs. An archive plan document is in preparation by each PI team and a draft statement of work as been issued. These documents as well as the system architecture will be reviewed during the system design review on 18-19 November 2003.