Ulysses spacecraft. Artwork of the spacecraft Ulysses orbiting the Sun. Looping prominences and sunspots (black areas) are seen on the Sun. Ulysses was launched in 1990 to study the Sun and its solar wind outside the ecliptic plane of the planetary orbits. It passed over the Sun's south pole in 1994 and its north pole the following year. These passes were during the minimum period of solar activity, and Ulysses observed a fast and stable polar solar wind. A second set of polar fly-bys in 2000-1 studied the more variable winds of the solar maximum. Ulysses is a joint European Space Agency (ESA) and NASA mission.