A joint ESA and NASA mission, Ulysses (named after the hero of Greek legend) has charted the reaches of space above and below the poles of the Sun for more than seventeen years. It provided the first-ever map of the heliosphere – the sphere of influence of the Sun – in the four dimensions of space and time.

Exploring our star's environment is vital if scientists are to build a complete picture of the Sun, how it works and its effect on the Solar System. In particular, the satellite studied the solar wind that blows non-stop from the Sun and carves out the heliosphere itself, which extends well beyond the outer limits of the Solar System.

Ulysses was equipped with a comprehensive range of scientific instruments to detect and measure solar wind ions and electrons, magnetic fields, energetic particles, cosmic rays, natural radio and plasma waves, cosmic dust, neutral interstellar gas, solar X-rays and cosmic Gamma Ray Bursts.

Ulysses was launched by Space Shuttle Discovery in October 1990. It headed out to Jupiter, arriving in February 1992 for the gravity-assist manoeuvre that swung the craft into its unique solar orbit. It has orbited the Sun three times and performed six polar passes. The mission concludes on 1 July 2008.