The purpose of the Giotto mission was to study Comet Halley during its closest passage to the Sun (known as perihelion) in 1986.
No-one expected the spacecraft to survive its battering from comet dust during this encounter. However, although Giotto was damaged during the flyby, most of its instruments remained operational. To the scientists' delight, the mission was extended to allow an unprecedented encounter with a second comet, Grigg-Skjellerup. In 1992, after a long hibernation, Giotto was reawakened for the closest ever cometary flyby.
The major objectives of the original mission were to: