Giotto made the first close-up images of a comet nucleus.
The European Space Agency spacecraft flew past Halley’s Comet on 14 March 1986. It approached to roughly 596 kilometres from the nucleus and returned the first images showing a solid, dark central body. The nucleus was later estimated to be about 15 kilometres long and 7 kilometres wide.
Giotto’s encounter occurred during an international campaign that also involved spacecraft from the Soviet Union and Japan. The probe survived a collision with a dust particle that damaged its instruments and temporarily interrupted communications.
Giotto did not orbit Halley’s Comet and did not return samples. Rosetta later became the first spacecraft to orbit a comet and deployed the Philae lander to its surface. Stardust, by contrast, collected cometary particles and returned them to Earth.