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Ulysses Status Report - February 2003

Ulysses Status Report - February 2003

The mission, now in its 13 th year of science operations, is progressing nominally, withspacecraft and all scientific instruments in good health. One Anomaly Report (ULY055"Early termination of open-loop slew") was issued during the reporting period. Themanoeuvre in question was the last in a series of four to calibrate the Upper Axial 1 (UA1)thruster. The early termination was traced to an error in a command file that had been editedby hand. Corrective action has been taken to ensure that in future, the Flight DynamicsCommand Analyser software processes all command files that have been manually edited.The first three UA1 calibration manoeuvres were successfully executed, making itunnecessary to repeat the failed manoeuvre. As noted in the last report, preparations for thenext NASA Sun-Earth Connections (SEC) Senior Review (to be held 10-13 June) areunderway. The 2003 Review will address funding priorities within NASA for FY 2004-2005,and issue guidelines for FY 2006-2007. On 25 February, Ulysses will be at a radial distanceof 4.65 AU from the Sun, and heliographic latitude 20: north of the solar equator, on its wayto aphelion.

Operations and Archive

All science operations during the reporting period have been nominal. At its meeting in October, 2002, the Ulysses Science Working Team agreed unanimously to do away with the formal 1-year proprietary period for Ulysses data. Data is now placed in public archive immediately following verification by the PI teams. The ESA Ulysses archive is accessible via the World Wide Web at URL: http://helio.estec.esa.nl/ulysses/archive/. Information regarding the data archive may be obtained from the Ulysses Data System Coordinator, Dr. C. Tranquille (Cecil.Tranquilleesa.int).

Science Highlights

Ulysses continues to observe the transition from a transient-dominated to a quasi-stable heliosphere from its unique out-of-ecliptic vantage-point. As the level of solar activity decreases, the Sun's magnetic dipole has started to dominate the global magnetic field configuration once again. The angle between the dipole and rotational axes, nearly 90° at solar maximum, has also decreased. As a consequence, the heliospheric current sheet that separates inward (negative) magnetic fields from outward (positive) magnetic fields has become less inclined with respect to the solar equator. These large-scale changes have had a significant effect on the particles and fields measured at Ulysses. Since October 2002, there have been no excursions into the high-speed (~750 km/sec) solar wind from the northern polar coronal hole, and Ulysses has spent much of the time in more variable, lower-speed flows. This is also reflected in the energetic particle profiles, which have shown only modest increases, with very few transient-related events. Nevertheless, the Sun is known to produce some of its most powerful eruptions in the declining phase of the solar cycle, so things could change at short notice.

Last Update: 1 September 2019
17-Oct-2021 06:14 UT

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