International Ultraviolet Explorer (IUE)

The International Ultraviolet Explorer was a joint project between NASA, ESA, and the United Kingdom’s Science and Engineering Research Council. IUE analyzed ultraviolet light between 115 and 325 nanometers, which is blocked from reaching ground telescopes by the Earth's ozone layer but often carries storm signals of cosmic upheavals. In its lifetime, IUE returned 104,470 ultraviolet spectra of all classes of celestial objects. Launched in 1978, IUE greatly exceeded its goal lifetime of 5 years and operated until 1996, making it the longest-lived and most productive astronomical satellite ever built at the time.

NASA provided the launch, spacecraft engineering support, and software for IUE. ESA provided the solar panels and a satellite command station outside of Madrid, Spain, and the UK provided the Vidicon cameras. Observing time was split between two spacecraft command stations. NASA operated the spacecraft for 16 hours per day from the Goddard Space Flight Center in Greenbelt, Maryland, and the Villafranca Satellite Tracking Station (VILSPA) near Madrid operated it for 8 hours per day.

On average, IUE made one hour-long observations every 90 minutes, around the clock. IUE’s geosynchronous orbit allowed for real-time operation, which made IUE very flexible. Astronomers came to the spacecraft command stations to direct their observations and inspect the data as they were collected, much as they do at ground-based observatories. Objects of study ranged from Halley’s comet and planets in the solar system to hot stars, supernova 1987A, and active galaxies powered by supermassive black holes. Even though its observing method (spectroscopy) was not readily understandable to the general public, the IUE mission is one of the biggest success stories in space science.

Learn more at https://science.nasa.gov/mission/iue/

https://www.esa.int/Science_Exploration/Space_Science/IUE_overview