Ulysses is a joint ESA/NASA mission studying the interplanetary medium and solar wind in the inner heliosphere, beyond the Sun's equator, for the first time.
The heliosphere is the immense magnetic bubble containing our solar system, solar wind, and the entire solar magnetic field. It extends well beyond the orbit of Pluto. While the density of particles in the heliosphere is very low (it's a much better vacuum than is created in a laboratory), it is full of particles of interest to heliospheric scientists.
The spacecraft's high-inclination orbit around the Sun took it over the solar south pole in 1994 and then the north pole in 1995. Ulysses then made a second southern solar pass above 70 deg latitude during September 2000 to January 2001, and a similar northern pass during September to December 2001. On 17 November 2006, the spacecraft started its third passage over the Sun's south pole.
Ulysses' high-gain antenna points continuously towards Earth, returning data for 8 h every day as it investigates the Sun's domain.