Ulysses and Hyakutake. Artwork of the unmanned solar spacecraft Ulysses passing through the tail of Comet Hyakutake in May 1996. In 1990, Ulysses was launched to study the Sun and its solar wind outside the ecliptic plane of the planetary orbits. It attained a polar solar orbit by swinging around Jupiter (1992). It passed over the north and south poles of the Sun (1994-5) at a minimum period of solar activity, observing a fast and stable polar solar wind. A second set of polar fly-bys (2000-1) studied the more variable winds of the solar maximum. Ulysses is a joint ESA and NASA mission.