Based on data retrieved by the largest ultraviolet space telescope of the time, "Astron", during its Halley's Comet observations in December 1985, a group of Soviet scientists developed a model of the comet's coma. The comet also was observed from space by the International Cometary Explorer (ICE). Originally named International Sun-Earth Explorer 3, the probe was renamed and freed from its Lagrangian point location in Earth's orbit in order to intercept comets 21P/Giacobini-Zinner and Halley. ICE made its closest approach to Halley's Comet on 28 March 1986.