World astronomers are becoming very concerned about their ability to carry out observations in ultraviolet light following recent announcements about the future of the Hubble Space Telescope. Hubble is most famous for the clear images it gives of distant objects from its vantage point above the Earth's atmosphere. It is less well known that its instruments are also sensitive to radiation outside the visible range that never penetrates to the Earth's surface. Observations of these wavelengths, including the ultraviolet, can only be carried out from space.

While a successor for the visible and infrared capability of Hubble is already being designed - the James Webb Space Telescope, planned for launch in 2011 - no similar replacement is on the drawing board to replace Hubble's ultraviolet capability. At present, approximately one third of the time allocated on the Hubble Space Telescope is devoted to ultraviolet observations.

Significant discoveries made in the past with ultraviolet observations include hidden white dwarf stars orbiting normal stars and revelations about their composition, halos of hot gas surrounding the Milky Way and other galaxies, and the realization that most stars are enveloped with hot gas, like the Sun's corona.

Professor Martin Barstow of the University of Leicester says, "When Hubble finally fails, access to one of the most important parts of the spectrum will end for the foreseeable future." And he will voice his concerns in a talk at the RAS National Astronomy Meeting at the Open University on Tuesday 30 March.

But Professor Barstow will go on to tell the meeting how a group of astronomers are hoping to fill the gap with an innovative mission called the World Space Observatory. While being significantly more sensitive than Hubble, it could be built and launched within 5 years. With participation from more than 20 different countries the World Space Observatory will be the first truly global space mission and will have contributions from developing nations taking their first steps in space research. However, political and financial support is needed from the various governmental space agencies to make the project a reality.

Prof Barstow said: "The World Space Observatory is a completely new approach to carrying out space science, spreading the overall costs across a much larger number of countries than in the past. At the moment, it is the only potential replacement for Hubble in the ultraviolet and it is essential that the world-wide community supports the project."