A prolific astronomical satellite, which was launched on a three-year mission in 1978 but is still active, is to be shut down in six weeks' time because of funding problems.
The International Ultraviolet Explorer pours out data which is used by astronomers worldwide. It has enabled the only weighing of a super-massive black hole; the tracking of the comet Hyatukake; and the recent proposition that certain stars have magnetic fields.
Funding of the satellite was, until last year, shared between United States space agency Nasa and the European Space Agency, ESA. Nasa stopped its share of the science operations and since then ESA has spent Pounds 5 million. But ESA's recent 3 per cent budget cut means it too is pulling the plug.
Astronomers said this week that the loss of IUE would be sorely felt. Sir Robert Wilson, emeritus professor in the department of physics and astronomy at University College London, who dreamed up the concept of IUE in the 1960s, said: "In the end it was an administrative decision to end it. It was the easiest area for them to save a little money. And it was ailing a bit."
Professor Wilson persuaded Nasa to build it after it was rejected by the ESA. Various lucky breaks gave it an excess of fuel which could last another 17 years.
IUE had two big advantages. Its orbit follows the Earth's rotation and is very high, varying between 30 and 70 thousand kilometres. It therefore has a view of the sky that is not obscured by Earth and can sit and watch a single event, such as Supernova 1987a, which went off in the Large Magellanic Cloud, rather than whizzing past it within 90 minutes.
IUE also observes in the ultra-violet, where many important events can be detected.
David Stickland, the United Kingdom's IUE project manager, said: "It has contributed to every branch of astronomy." Up to 500 doctoral theses and 3,500 refereed papers have derived from IUE data.
Ian Howarth, reader in astronomy at University College London, said: "IUE is still making fabulous discoveries."
Professor Wilson said: "With the passage of time the space agencies are not really interested in the space science." Instead, he said, they want to "build rockets and hit the headlines".