The deep-space probe Ulysses had been on its mission to explore the Sun’s surface and the region close to the Sun, investigating the structure and variations of the heliosphere since 1990. The mission finally ended on 30 June 2009 and holds the record as the longest running European Space Agency operated mission at 18 years and 246 days.
The mission’s objectives were to explore the regions to the south and north of the solar equator which are impossible to view from Earth. Its findings are vital for a better understanding of the Sun’s effects on the solar system. Ulysses provided the first-ever map of the heliosphere from the equator to the poles.
Following its launch on 6 October 1990, the research probe first flew in the direction of Jupiter in order to use the planet’s gravity to swing it into its solar polar orbit. This ‘gravity assist manoeuvre’ took place in February 1992. In 1994, Ulysses became the first probe to cross the southern polar region of the Sun, and in 1995 it crossed the North Pole. In 1998, Ulysses successfully completed the first orbit around the Sun. In 2001, at the critical phase of the Sun’s 11-year ‘sunspot’ activity cycle, Ulysses reached the northern polar region once again. In early 2004, Ulysses had its second encounter with Jupiter, which enabled it to re-enter solar polar orbit. The spacecraft began its third solar pole pass on 17 November 2006 at 80° ecliptic to the South Pole.
Ulysses is a joint ESA–NASA mission. The Ulysses spacecraft was built under the leadership of Airbus Defence and Space for ESA, which managed mission operations with NASA’s Jet Propulsion Laboratory.