International Ultraviolet Explorer (IUE)

Ultraviolet observations of the Universe

  • Completed
  • Launched 26 January 1978
  • Ended September 1996
The International Ultraviolet Explorer (IUE) has been one of the most productive satellites ever built. IUE provided invaluable information about stars located millions of kilometres away as well as objects much closer to home, such as comets approaching our part of the Solar System.

IUE was originally planned as a three to five year mission to analyse ultraviolet light from the stars. By the time it was eventually shut down, more than 18 years later, it had lasted six times as long as originally planned.

The International Ultraviolet Explorer did not produce images but measured the energies of ultraviolet rays coming from celestial objects, giving insight into the physical conditions in those objects.

IUE's best known observation was of Halley's Comet when it visited Earth in 1986. The satellite was also central to the extensive programme of observations of Jupiter’s atmosphere during the impact of Comet Shoemaker-Levy in 1994.

Although it did not capture the public imagination in the way that Hubble has, IUE remains one of the most successful missions of all time. Scientists still use data gathered by the satellite, more than a decade after the mission ended.

Mission facts

  • IUE was a joint mission between ESA and NASA with UK involvement.

  • For 18 years, the satellite made one hour long observation every 90 minutes, making it one of the most productive missions in the history of space exploration.

  • The mission was the precursor of more recent observatories in space, such as Hubble.

  • Archived data from IUE was the first from any mission to be made available online. This was back in 1985, before the invention of the World Wide Web.


Each of the three partners was responsible for a key part of IUE

NASA provided the spacecraft, two of the instruments and one ground observatory. ESA provided the solar panels and the second observatory. The UK supplied detectors and sensors.

The reliability of IUE's operation throughout its 18 years in space was remarkable. Although the back-up cameras developed a fault, the primary cameras remained fully operational. And despite the failure of four of its six gyroscopes, control of the satellite’s position remained precise to the last.

UK involvement

As one of the three main partners, the UK had strong involvement in the design, instruments and science of the mission.

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