Japan's second deep-space probe. The first was Sukigake, identical except for the scientific instruments on board. Launched in August 1985 to carry out a fly-by of Halley's Comet, Suisei had its closest approach to the comet in March 1986, detecting cometary water, carbon monoxide, and carbon dioxide ions.
The mission was intended to include an encounter with comet Giacobini–Zinner in 1998, but Suisei exhausted its on-board fuel supply in February 1991 and Earth contact with the craft was lost.