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Ulysses Status Report - November 2005

Ulysses Status Report - November 2005

Mission StatusA major milestone for Ulysses was reached on 6 October, namely the 15th anniversary of the launch from Cape Canaveral on board the space shuttle Discovery. After 15 years of operations, and a journey of 7 billion kilometres, the spacecraft and its scientific payload remain in good health, and no anomalies have occurred during the reporting period.

The situation concerning the budget for NASA's contribution to the mission, noted as a concern in the previous report, has shown significant improvement. The budget for mission operations and data analysis for Sun-Solar System Connections missions currently in their extended operational phase has largely been restored. Nevertheless, the outcome of the next Senior Review, to be held on 14-15 November, will still be important in determining the level of support available for Ulysses investigators funded by NASA.

On 1 November 2005, Ulysses will be at a radial distance of 4.7 AU from the Sun, and heliographic latitude 33° south of the solar equator.

Operations and Archive

All science operations during the reporting period have been nominal. Payload operations are being conducted according to the pre-determined power-sharing plan. The current payload configuration will be maintained until Spring 2007, when the spacecraft is close enough to the Sun to allow the Cold Case Heater (needed to keep critical parts of the spacecraft platform at a safe temperature) to be switched off. The ESA Ulysses archive is accessible via the World Wide Web at URL: http://helio.esa.int/ulysses.

Science Highlight

In early September the Sun, although far into the declining phase of the current sunspot cycle, produced a display of major activity. This included one of the largest solar flares of cycle 23, an X17+ on 7 September, that occurred as the active region responsible rotated into view of the Earth on the Sun's east limb. A very large and very fast coronal mass ejection (CME) was also associated with this flare. At the time, Ulysses was positioned almost directly behind the Sun as seen from Earth, at 30 degrees south latitude and 4.8 AU from the Sun. This geometry provided Ulysses with a unique view of the source of the activity for several days prior to its appearance on the visible (from Earth) solar disk. Based on observations from the Ulysses radio experiment, it is likely that region 10808 produced at least 4 intense flares while on the far side as viewed from Earth. The X17+ flare produced an unusually intense radio burst observed by Ulysses, and the shock driven by the CME was observed in situ at Ulysses on 14 September, implying a transit velocity of ~ 1210 km s-1 over a distance of almost 5 AU! The radio bursts associated with some of the X-class flares occurring after the X17+ flare had surprisingly low intensities. This is consistent with what was seen for the 2003 "Halloween" events. A possible explanation is that the entire inner heliosphere was filled with energetic electrons to a flux level sufficient to block the plasma instability that would otherwise initiate the radio emission process.

 

Last Update: 1 September 2019
6-May-2021 01:11 UT

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