Launched from Earth in October 1990, Ulysses was sent toward Jupiter because no rocket could place a spacecraft directly into a high-inclination solar orbit. After a 16-month coast, a Jupiter gravity assist near day 490 bent the trajectory out of the ecliptic into a bound orbit inclined about 76 degrees, carrying Ulysses over the Sun's poles for the first time. The mission studied the heliosphere's three-dimensional structure, solar wind at high latitudes, and cosmic rays. Jupiter's gravity changed Ulysses's orbital inclination by exploiting the planet's enormous gravitational field as a natural 'crank' — a manoeuvre impossible with chemical propulsion alone.