Double Star Status Report - November 2005
The perigee of TC-2 has been decreasing due to the Sun-Earth perturbations (height is now around 250 km) and atmospheric drag is slightly changing the orbit. The planning has been affected since orbit predictions four weeks in advance can have a shift of up to one hour. This affects the PEACE commanding that has to be switched-off in radiation belts. A temporary work around solution is being put in place. The minimum in perigee altitude was reached in September and the perigee will rise again in the next few months.
Operations and Archiving
The European Payload Operation System (EPOS) co-ordinates the operations for the seven European instruments on TC-1 and TC-2 and is running smoothly. The new contract for the extension of EPOS is in preparation. It will combine Cluster, Double Star and Mars Express Science operations. ESOC acquired on average about 3 hours of data per day using the VILSPA 2 antenna with an availability rate of 99.94% between April 2005 and July 2005.
Science Highlights
A total of 24 papers have been accepted for the special Annales Geophysicae issue on first results from Double Star. They are now in print. A special session on results from Double Star and Cluster will take place at the AGU in San Francisco. Early 2005, the Double Star and Cluster spacecraft observed a flux transfer event (FTE) that is a freshly reconnected magnetic flux tube with one side in the solar wind and one side in the magnetosphere. The FTE could be observed at small scale with the Cluster spacecraft (200 km) and at large scale with Double Star (18 000 km away from Cluster). Particles and fields observations suggest that the five spacecraft observed the same FTE. The FTE was elongated along the vertical z axis and a preliminary estimate of its motion is consistent with the reconnection model.