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Double Star Status Report - April 2005

Double Star Status Report - April 2005

Mission StatusThe two spacecraft and the instruments are operating nominally. The magnetometer data are used to derive the attitude of the spacecraft. The satellite manufacturer, CAST, has made a model of the evolution of the attitude of the two spacecraft. The spin axis of TC-1, the equatorial spacecraft, will have drifted by about 9° at the end of 2006. On the other hand TC-2 spin axis is drifting faster and will reach 30° by July 2006. There will therefore be enough power up to the end of mission (end of July 2005) and an extension up to end 2006 will be proposed.

The European instruments are operating nominally. Resets on PEACE (electron sensor) are still occurring. The instrument is now switched on and off five times along the orbit to be able to recover from eventual resets.

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. ESOC acquires data on average about 3.3 hours per day with the VILSPA 2 antenna. The availability of the antenna was above 99% between December 2004 and February 2005.

Science Highlights

Previous Cluster observations have shown that the flapping motions of the Earth's magnetotail are of internal origin and that waves are emitted from the central part of the tail and propagate toward the tail flanks. Using conjunctions between Double Star and Cluster, simultaneous observations were made both at 10-13 and 16-19 RE. Neutral sheet oscillations were observed by the Cluster and Double Star satellites on 5 August 2004. The study showed that such waves can be observed as close to the Earth as 11 RE, in the neighbourhood of the magnetotail hinge point.

Very intense, solar activity occurred between 3 and 13 November 2004, stimulating one of the most intense episodes of geomagnetic storms. The Dst Index recorded at Kyoto University over the period concerned reached a maximum value of –383 nT. The NUADU instrument on Double Star TC-2 observed from over the North Pole Energetic Neutral Atoms (ENAs) produced in association with the great enhancement of the ring current produced during the storm. The emissions wrapped around the Earth from midnight to dusk. The ENA intensity was strong at midnight because of the high flux of parent ions. An ENA image was recorded simultaneously by the HENA experiment on the IMAGE spacecraft which was at that time located in the Southern hemisphere, and thus viewed the ring current from the South. The general morphology displayed in the two images is consistent. These are the first comparisons made between dedicated ENA images of the ring current taken simultaneously from two separated points in space.

A total of 27 Papers have been submitted for the special Annales Geophysicae issue on first results from Double Star. They are now in the review cycle. A special session on results from Double Star and Cluster will take place at the EGU in Vienna. This will be the first time that Double Star results are shown in an international conference.

Last Update: 1 September 2019
28-May-2024 11:29 UT

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