A NASA spacecraft that made the first encounter with a comet. ICE made a rendezvous with the comet Giacobini–Zinner in September 1985 and passed through its tail, taking measurements. It later went into the vicinity of Halley's Comet in March 1986, becoming the first spacecraft to directly observe two comets.

ICE was launched in 1978 with the name of International Sun-Earth Explorer 3 (ISEE-3) and, in coordination with ISEE-1 and ISEE-2, was intended to monitor the interaction between the solar wind and the Earth's magnetic field. NASA then decided to change its trajectory to intercept the comet, and renamed the spacecraft accordingly. Its operations were ended in 1997, but its flight continued with status checks in 1999 and 2008. In May 2014 communication was re-established and the thrusters were later fired successfully. But all contact was lost in September 2014.