More stars in our eyes

August 11, 2000

A Pounds 2m makeover will vastly expand the Lovell Telescope's potential. Steve Farrar reports.

The dusty veil that shrouded the nearby starburst galaxy M82 was lifted late last year. The British-led team of radio astronomers responsible revealed a scene of unparalleled stellar carnage, a galaxy peppered with the brilliant remnants of dozens of supernovae.

These powerful explosions have been repeatedly ripping through the galaxy, making M82 surely the worst neighbourhood in the universe for real estate.

The startling image was produced from data gathered by radio telescopes across the world and at the heart was one of the icons of British science - the unmistakable Lovell Telescope at Jodrell Bank in Cheshire.

This giant ear to the heavens has epitomised technological innovation for decades and remains a place of cutting-edge research. But now Manchester University's famous radio observatory is preparing for a rebirth and looking forward to an even more glorious future.

It is 50 years since the first sketches of a steerable, giant radio telescope were laid in front of Sir Bernard Lovell, the pioneering astronomer who later gave his name to the 76m dish. In its 43 years of operation, it has notched up many scientific milestones, from probing the nature of pulsars to discovering light-bending gravitational lenses. It is currently searching for rapidly rotating millisecond pulsars that might prove more accurate time keepers than the best atomic clocks.

But modern astronomy demands radio telescopes that work at far shorter wavelengths, so Jodrell's giant dish is to receive a Pounds 2 million make-over, courtesy of the government's Joint Infrastructure Fund.

Observatory director Andrew Lyne says: "It will completely revolutionise the telescope's sensitivity and the sort of objects we'll be able to search for."

The dish is to be resurfaced with galvanised steel panels, accurate to within 2mm. Holographic profiling techniques will be used to set each panel individually and a new control system installed to enhance the precision with which it can be pointed at distant objects.

The improvements to the Lovell Telescope are significant in their own right, but there is a more ambitious project that would really set the jewel within a more appropriate crown.

Jodrell Bank's telescopes are part of a nationwide network known as Merlin (multi-element radio-linked interferometer network) that consists of seven linked telescopes that stretch from the Welsh borders to Cambridge - a virtual radio dish some 217km across. It is a powerful tool that has helped British astronomers study supernovae, star formation, the structure of galaxies and the fundamental physics of creation. It also shares the same resolution as the Hubble Space Telescope, allowing images to be easily compared.

However, it too is on the brink of a new age. Network director Phil Diamond says that e-Merlin, as its future incarnation will be known, should be 30 times more sensitive.

This leap forward would be produced by linking the constituent telescopes with broadband fibreoptic cables laid beneath the road surface. At present, Merlin's microwave links cannot carry all the data its telescopes gather. "It means we're throwing away an enormous amount of data," Diamond says.

Technical proposals are being drawn up that could cost up to Pounds 6 million.

Much rests on the outcome of an international review of Merlin due in September - the astronomers hope the case for the upgrade will prove overwhelming.

If given the go ahead, e-Merlin would help scientists carry out a cosmic census of stellar population growth by identifying telltale signs of star formation.

The analysis of distant gravitational lenses will reveal new perspectives on dark matter as well as the basic constants of cosmology.

And it would find not dozens but hundreds of supernovae in M82, as well as the frenetic starbirth that has made the galaxy so turbulent in the first place.

WHEN BIGGER IS BETTER

Astronomers are planning three complementary giant telescopes to explore the heavens in unprecedented detail and at previously unattainable distances.

The first will be the Atacama Large Millimetre Array, which will detect millimetre-wavelength signals from a site in Chile.

There are also proposals for an Extremely Large Telescope, which would collect light with a 100m mirror, and radio astronomers are working on their own instrument, dubbed the Square Kilometre Array.

One of the largest scientific instruments ever built, SKA will be made up of a host of radio telescopes with a total collecting area of a square kilometre - 220 times the size of the Lovell Telescope.

This is the minimum needed to pick up the weak signals produced by distant concentrations of the universe's most abundant substance - atomic hydrogen.

Peter Wilkinson, professor of radio astronomy at Jodrell Bank and a member of the project's international steering committee, says: "We do not know what the universe will look like at that level of sensitivity, but when you crank up the sensitivity by an order of magnitude you will always find new things."

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