When was the first spacecraft to visit a comet up close?

ESA’s Giotto spacecraft made its historic flyby of Halley’s Comet on 14 March 1986. It became the first spacecraft to observe a comet nucleus at close range and returned the first detailed images of a comet’s dark, irregular core. The mission showed that comet nuclei are solid bodies made of dust and ice rather than diffuse clouds. Giotto’s images and measurements transformed comet science and influenced later missions such as Deep Impact and Rosetta.