Astronomers want bigger telescopes

Big science: The Terrestrial Planet Finder

By BBC News Online science editor Dr David Whitehouse

If you are an American astronomer then the next decade may offer unprecedented opportunities to study the Universe.

If you are an American taxpayer then you may wonder why hundreds of millions of dollars are being spent on several large telescopes doing essentially the same thing.

According to a new report by the National Science Foundation (Nsf) looking at what astronomers require in the next decade or so, the highest priority is a so-called Next Generation Space Telescope (NGST).

This would be far more advanced than the Hubble telescope currently in orbit. The report says it should "dramatically increase our understanding of how the first stars and galaxies formed billions of years ago and how stars and planets form today.

Professor Joseph H. Taylor of Princeton University, one of the report's authors said: "New discoveries have the potential to shed light on many key challenges in astronomy, including identifying the total amount of matter in the universe as well as its age, evolution, and ability to support life.

Bigger, better, more expensive.

Christopher F. McKee of the University of California added: "We also may soon understand how black holes are formed and how the astronomical environment affects Earth."

It is hoped that the Next Generation Space Telescope will have 100 times the sensitivity of Hubble and will provide images 10 times as sharp. Inevitably, technology this good will cost over a billion dollars.

The Next Generation Space Telescope: 100 times the sensitivity of Hubble

In addition, the Nsf envisages a large telescope on the ground as well. The Giant Segmented Mirror Telescope is a high priority says the report. It could provide the means to trace the evolution of galaxies and study the matter between them, in much the same way as the NGST is planned to do.

There is also the Constellation-X Observatory that the report says will be the premier instrument for studying the formation of black holes.

According to the study the Very Large Array radio telescope in New Mexico, now 20 years old, needs to be expanded to enable it to study distant galaxies and the disk-shaped regions around stars where planets form.

Planet search

Another large ground-based survey telescope may be required to catalogue 90% of the near-Earth objects (NEOs) larger than 300 meters (984 ft) in diameter that may threaten our planet.

Also high on the astronomers' wish-list is the Terrestrial Planet Finder, which in terms of its goal and complexity is considered by some to be the most ambitious science mission ever attempted by Nasa.

It would detect and study planets around nearby stars and search for evidence of life.

Other highly rated programmes that should be pursued include a large telescope to study gamma rays from space, an instrument to measure the gravitational waves predicted by Einstein's relativistic theory of gravity, and a powerful telescope to study the Sun.

Also essential according to the panel members is a "virtual observatory" that would make large sets of astronomical data available to scientists and the public on the internet.

The report also recommends increased investment in astronomy theory, saying that it is theorists who provide the ideas that guide the choice of instruments and the interpretation of what is seen.