# International Ultraviolet Explorer > astronomical observatory satellite **Wikidata**: [Q51509](https://www.wikidata.org/wiki/Q51509) **Wikipedia**: [English](https://en.wikipedia.org/wiki/International_Ultraviolet_Explorer) **Source**: https://4ort.xyz/entity/international-ultraviolet-explorer ## Summary The International Ultraviolet Explorer (IUE) was a space telescope launched in 1978 that operated for nearly 18 years, observing ultraviolet light from celestial objects. It was a joint project between NASA, the UK Science Research Council, and the European Space Agency (ESA). The satellite was decommissioned in 1996 after providing valuable astronomical data. ## Key Facts - Launched on January 26, 1978, at 17:36:00 UTC from Cape Canaveral Space Launch Complex 17A - Operated for approximately 18 years until decommissioning on September 30, 1996 - Weighed 671 kilograms at launch - Had a cospar ID of 1978-012A and was also known as Explorer 57 and SAS-D - Classified as a space telescope, artificial satellite of Earth, and derelict satellite - Operated by NASA and the European Space Agency - Launched using a Delta 2000 rocket (628/D138 configuration) ## FAQs ### Q: What was the International Ultraviolet Explorer's primary mission? A: The IUE was designed to observe ultraviolet light from celestial objects, providing astronomers with data about stars, galaxies, and other astronomical phenomena that cannot be observed from Earth's surface due to atmospheric absorption of UV radiation. ### Q: How long did the International Ultraviolet Explorer operate? A: The IUE operated for nearly 18 years, from its launch on January 26, 1978, until its decommissioning on September 30, 1996, far exceeding its original planned mission duration. ### Q: Who operated the International Ultraviolet Explorer? A: The IUE was operated jointly by NASA (National Aeronautics and Space Administration) and the European Space Agency (ESA), with additional contributions from the UK Science Research Council. ## Why It Matters The International Ultraviolet Explorer represented a groundbreaking achievement in space-based astronomy, providing unprecedented access to the ultraviolet spectrum for scientific research. Before IUE, astronomers had limited ability to study UV radiation from celestial objects because Earth's atmosphere blocks most ultraviolet light. This satellite enabled continuous, real-time observations that revolutionized our understanding of stellar evolution, interstellar medium, and galactic structure. IUE's long operational life and its ability to respond quickly to unexpected astronomical events made it an invaluable tool for the scientific community. The data collected by IUE contributed to over 3,500 scientific papers and helped establish ultraviolet astronomy as a crucial field of study. Its success demonstrated the value of international collaboration in space science and set the stage for future space telescopes like the Hubble Space Telescope. ## Notable For - First high-orbit astronomical observatory providing real-time UV observations - Longest operating astronomical satellite of its time (nearly 18 years) - Joint NASA-ESA-UK collaboration that set the standard for international space science projects - Provided continuous UV spectroscopy data that transformed our understanding of stellar atmospheres and interstellar matter - Successfully operated well beyond its planned mission lifetime, demonstrating exceptional engineering reliability ## Body ### Technical Specifications and Design The IUE was a 671-kilogram satellite launched aboard a Delta 2000 rocket from Cape Canaveral. It was designed as a 45-centimeter aperture ultraviolet telescope capable of both high and low-resolution spectroscopy. The satellite featured two spectrographs covering wavelengths from 1150 to 3200 Angstroms, allowing it to observe a wide range of astronomical phenomena. ### Operational Characteristics Unlike many space telescopes that operate autonomously, IUE was designed for real-time operation, with astronomers able to direct observations from ground stations in the United States and Spain. This unique approach allowed for rapid response to unexpected astronomical events and provided a level of flexibility that proved invaluable throughout its mission. The satellite maintained a geosynchronous orbit, enabling continuous communication with ground stations. ### Scientific Contributions Throughout its 18-year mission, IUE made numerous groundbreaking observations, including studies of hot stars, active galactic nuclei, planetary atmospheres, and comets. The satellite played a crucial role in understanding stellar winds, mass loss from stars, and the composition of interstellar gas. Its data proved essential for studying phenomena ranging from nearby planets to distant quasars. ### Legacy and Impact The IUE's success established ultraviolet astronomy as a vital field and demonstrated the scientific value of long-duration space missions. Its operational model influenced the design of subsequent space telescopes, and the vast archive of UV data it generated continues to be used by astronomers today. The satellite's decommissioning in 1996 marked the end of an era in space-based ultraviolet astronomy, but its contributions continue to influence the field. ## References 1. [Source](https://github.com/JohnMarkOckerbloom/ftl/blob/master/data/wikimap) 2. Jonathan's Space Report 3. Freebase Data Dumps. 2013 4. [Source](http://sdc.laeff.inta.es/ines/docs/report.pdf) 5. [Source](https://sci.esa.int/web/iue/-/47362-fact-sheet) 6. National Library of Israel Names and Subjects Authority File