Ulysses 10th anniversary meeting gets off to maximum start
4 October 2000If the Voyager spacecraft are ever to cross the heliospheres boundary, they will probably do so within the next year or two before the effects of this years solar maximum cause the heliosphere to expand. Ed Stone from the Jet Propulsion Laboratory, California, told an international gathering of solar scientists yesterday afternoon, that the two spacecraft are now probably closer to the boundary, which estimates put at 80-115 Astronomical Units (AU) from the Sun, than the 16 AU distance between them.
Dr Stone was giving an introductory keynote address to the 34 ESLAB symposium on the 3D heliosphere at solar maximum, which began three days of proceedings at ESTEC in the Netherlands. The meeting will be discussing new results from Ulysses and other spacecraft as the Sun reaches solar maximum.
Changes to the structure of the solar corona as the Sun progresses from minimum to maximum activity were vividly illustrated by Mike Andrews from Computational Physics Inc. at the Naval Research Laboratory, Washington DC, who showed a series of images taken by the choronograph on the SOHO spacecraft. At solar minimum, coronal streamers were seen emerging only from around the Suns equator, but in December 1997 a transition took place, marked by the appearance of long-lived streamers emerging from high latitudes. This is illustrated by the two accompaying figures, both taken by SOHO's Large Angle and Spectrometric Coronagraph (LASCO) C2 instrument, the first image was taken around Solar minimum on 13 May 1996, the second on 30 September 2000, near Solar maximum.
This meeting is bringing together friends and colleagues from around the world that have worked together for many, many years, said Peter Wenzel, Head of Solar System Division at ESTEC during the welcome address. As well as now sharing a common interest in the structure and extent of the heliosphere, Ulysess and the Voyager spacecraft also share the distinction of carrying some of the oldest hardware in space. Klaus Fahlenbock from Dornier (now Astrium), the prime contractor, reminded delegates that Ulysses was built 18 years ago, even though the 10th anniversary of its launch is being celebrated this week.