International Ultraviolet Explorer was the first space observatory primarily designed to take ultraviolet (UV) spectra. The satellite was a collaborative project between NASA, the United Kingdom's Science and Engineering Research Council and the European Space Agency (ESA), formerly European Space Research Organisation (ESRO). The mission was first proposed in early 1964, by a group of scientists in the United Kingdom, and was launched on 26 January 1978, 17:36:00 UTC aboard a NASA Thor-Delta 2914 launch vehicle. The mission lifetime was initially set for 3 years, but in the end, it lasted 18 years, with the satellite being shut down in 1996. The switch-off occurred for financial reasons, while the telescope was still functioning at near original efficiency.