Ulysses is an unmanned probe designed to study the Sun at all latitudes. The spacecraft, named for the Latin translation of "Odysseus", was launched in October 1990 from the Space Shuttle Discovery (mission STS-41) as a joint venture of NASA and the European Space Agency. It was originally code-named the International Solar Polar Mission.

On leaving Earth, the spacecraft became the fastest ever artificially-accelerated object. It arrived at Jupiter in February 1992 for a swing-by maneuver which brought it out of the ecliptic plane, in order to investigate the polar regions of the Sun. In 1994-5 and again in 2000-1 it explored both the northern and southern solar polar regions, which gave many unexpected results. In particular the southern magnetic pole was found to be much more dynamic and without any fixed clear location. It is, of course, wrong to say that the Sun has no magnetic south pole. The Sun is not a magnetic monopole, the pole is merely more diffusely located than the north pole.

On May 1, 1996, the spacecraft unexpectedly crossed the ion tail of Comet Hyakutake (C/1996 B2), revealing the tail to be at least 3.8 AU in length.

Ulysses approached aphelion in 2003/2004 and made observations of Jupiter. [1]

Ulysses' mission has been extended until at least March 2008, enabling it to continue operating while flying over the Sun's poles for the third time in 2007 and 2008. [2]

External links

• NASA/JPL Ulysses website
• ESA Ulysses website
• ESA/NASA/JPL: Ulysses subsystems and instrumentation in high detail