The Ulysses mission (a joint venture between ESA and NASA) represents the first attempt in the history of mankind and of space research to explore the third dimension of the solar system—underneath and above the ecliptic plane. The European spacecraft was launched on 6 October 1990 by the American shuttle Discovery in the direction of Jupiter, whose gravitational attraction it uses to acquire the proper velocity and to change the plane of its orbit in order to fly above the poles of the Sun in 1994 and 1995. The objectives of the mission are studies of the solar wind, the heliospheric plasma and the solar magnetic field in that region of the Solar System where it extends radially, i.e. above the poles. The mission can fulfil several other objectives in the field of solar physics and other areas such as the propagation of cosmic rays, the penetration of the interstellar gas in the solar system, gamma-ray bursts and gravitational waves. The mission is now fully operating. Preliminary results obtained when the satellite was en route to Jupiter and during the fly-by of Jupiter are presented in the article. Their quality and novelty already indicate that this unique mission will achieve its objectives and be a new success for European space science.