Launched on 2 July 1985 by Ariane-1, the Giotto probe passed, on March 13, 1986, 600 km of the nucleus of Halley's comet. The project was a success. It was the first time that such a precise image of a comet nucleus was obtained.
This confirmed that comets were made of a mixture of rocks and ice. This ice sublimates under the effect of the solar radiation and sends dust in space as shown by the image at left. Note that this release of dust severely damaged the probe.