IUE, International Ultraviolet Explorer, was a joint venture between ESA, the United States and the United Kingdom. Launched into geosynchronous orbit in 1978, IUE was the longest lived astronomical satellite ever, working for over 18 years instead of the planned seven. IUE studied ultraviolet radiation and was specialized in observing objects with a temperature of 10,000 to 100,000 degrees C. Among IUE's many remarkable discoveries were: the hot cloud surrounding our Milky Way, molecular sulfur emission from the nucleus of a comet, and identification of previously unknown star companions to cool stars.
EURECA, the European Retrievable Carrier, is ESA's heaviest (4,500 kg) research satellite. Eureca stays in space several months at a time, after which it is brought back to Earth for servicing and resupplying for the next mission. Its first mission was in 1992.
