If you dish upon a star

Brian Johnston listens to the mysterious sounds of distant galaxies within the 'giant ear' of the Parkes radio telescope.

I'm driving north along the Newell Highway out of Parkes through an undulating landscape of wheat fields and bored-looking sheep. Gum trees and sagging barbed-wire fences decorate the roadside and, in the field beyond, a farmer is rolling up rounds of hay.

Quintessential rural Australia drifts by until suddenly - almost shockingly - a bold metal structure looms out of the landscape: the CSIRO Parkes Radio Telescope, a vast white ear straining skywards to listen to the reaches of the universe.

"What's it doing in the middle of a sheep paddock?" the Prime Minister memorably asks about the telescope in The Dish, the feel-good Aussie movie of 2000 that has drawn visitors to Parkes ever since. The answer is the region has low winds and relative isolation from radio interference, at least most of the time. Mobile phones are the biggest annoyance for astronomers but even a farmer using his microwave causes disruption.

"Please turn off all mobile phones, video cameras, electronic and electrical equipment," says a sign in the car park as I pull up among the gargantuan motorhomes of grey nomads. I hurry past and through the visitors' centre to goggle at the dish, as improbable as an alien landing in this rural setting. Its 64-metre diameter makes it one of the world's largest radio telescopes, balanced precariously - yet rather elegantly - on a little round tower that could easily be a Dutch windmill.

Standing 100 metres or so from the radio telescope is as close as visitors usually get. This year, however, for the telescope's 50th anniversary CSIRO is holding two rare open days that will get visitors right inside the facility on a 40-minute tour - up the tower to just below the surface of the dish. Astronomers and technicians will act as guides and explain how the telescope is operated.

I'm lucky to take an early tour in the company of the head of astrophysics for CSIRO, Dr Simon Johnston. As we enter the control room directly under the telescope, he remarks that the dish and its counterweight above us weigh 2000 tonnes. "There aren't many radio telescopes in the world where the control room is actually under the dish. That means we can hear the telescope moving as it tracks the sky," he says gleefully, as if relishing the idea that tonnes of machinery are grinding above our heads.

The control room seems surprisingly devoid of computers. There are no more than half a dozen screens, showing where the telescope is pointing, what's happening in its focus cabin and wind speed and direction. More prominent are racks of music CDs, revealing eclectic if slightly old-fashioned tastes among astronomers: Brahms, the Blues Brothers, the Rolling Stones.

We climb the stairs, passing a newspaper quote from December 2000 pinned to the wall: "The Australian Telescope and its astronomers are among the country's overlooked treasures." Certainly overlooked by renovation rescuers, as the worn red carpet and laminate walls look as if they haven't been changed since the telescope was opened in 1961.

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Most people know little about this amazing scientific endeavour beyond its involvement in the 1969 Apollo 11 mission when, as portrayed in The Dish, Parkes relayed pictures of Neil Armstrong's moon walk to the waiting world. However, while Parkes played a crucial role in this and many subsequent NASA missions, these form a minor part of its scientific research.

"What we're really trying to do is capture incredibly weak radio signals from the far universe," Johnston says. "The parabolic dish focuses them onto a receiver, which amplifies them millions of times over, enabling us to detect objects as much as 20,000 million light years away."

He leads me into an upper room that smells of hot machines and is noisy with airconditioning units that cool banks of computers. Willy Wonka wires loop in a multicoloured liquorice tangle and electronic gadgetry blinks and winks. When Johnston pulls up a floor tile, it reveals more cabling and scattered mouse poison. Computer wires have been chewed through during the recent mouse plague and Johnston says they also have occasional problems with bogong moths.

"They fly into the laser beams that lock the telescope in position as it tracks around, causing the telescope to suddenly stop," he chortles, as if amused his 2000-tonne machine could be so puny. Another clamber brings us out to the top of the tower immediately below the dish, where I inspect the elevation gearboxes that move the telescope up and down and the azimuth track that swivels it around so it can follow the movement of the sky relative to Earth.

In the twister room, an elaborate and clever arrangement prevents cables becoming entangled as the telescope rotates. Now right above my head, the dish itself is a monumental spider's web of steel.

This is as far as the public will get during the October open days; there's no walking or playing cricket on the surface of the dish as portrayed in the movie. But back on the ground, visitors will be able to attend Q&A sessions with astronomers and use optical telescopes - even throughout the daytime - to view the sun, Jupiter, Venus and stars such as Alpha Centauri. Staff dressed as astronauts and Einstein will also be on hand to engage the kids.

I take a break at the visitors' centre cafe. The food comes with coy names such as Quasar quiche and Saturn sandwiches, though the waitress doesn't crack a smile when I ask if I can have my Celestial chicken wrap with a sprinkling of stardust. Still, the food is tasty and the light-filled space has splendid views of the telescope.

A last slurp of my Milky Way shake and it's time to explore the small visitors' centre. Because of tight restrictions on radio interference, the centre limits its use of computers and electric motors, making it seem a little old-fashioned. Gravity wells, logic puzzles and scales that show your weight on the moon and Mars provide passing distractions.

Curved mirrors reflect my alternatively elongated and bloated body like a Luna Park amusement, on the rather thin premise that this is how the dish reflects radio waves onto its receivers.

In the theatrette, 3D movies are also skimpy on science but entertain the kids with tourist flights to Mars over landscapes that look like the Bungle Bungles.

The problem with radio telescopes, no doubt, is that they just aren't as sexy as optical telescopes. Some visitors arrive expecting to stargaze on stunningly beautiful nebulae, only to come away disappointed.

Still, I find something baffling and thrilling about radio signals, emitted naturally by everything from pulsars to galaxies and supernovas. They have enabled the Parkes facility to detect the most distant objects in the known universe and help in the current hunt for gravitational waves, a ripple in space time predicted by Einstein.

My favourite display is a model of the telescope that can be moved to point at pulsars hidden in a photographic Milky Way on the wall. First discovered in 1967, pulsars were initially called LGMs (little green men) because the radio signals they emit are so regular it was thought they could only be artificial.

Now, as I jab buttons and the dish swivels, I tune in to the mysteries of the universe. The Crab pulsar sounds like a high-pitched motor boat, the Vela pulsar like tom-tom drums and B1937+21 like a demented mosquito.

Johnston has studied pulsars for 25 years but he, too, remains awestruck by the super-dense remnants of collapsed stars.

"I find it quite mind-boggling that these very small stars, spinning at 600 times a second, should even exist," he says. "And yet here we are, gathering their feeble radio signals after they've travelled 10,000 light years through the galaxy before arriving at Parkes."

As if compelled, we both turn our faces to the sky, from which radio signals are falling down all around us, teasing us with meaning.

This is what is so enthralling about a visit to the dish: a trip to a sheep paddock in rural NSW that brings you to the far reaches of the universe and makes you marvel.

FAST FACTS

Getting there

Parkes is 365 kilometres west of Sydney. Regional Express flies to Parkes from Sydney.

Open days The Visitors Discovery Centre is open daily. Anniversary open days are October 8-9, offering rare guided tours through the telescope. Opera at the Dish is held on October 8; see parkesunderthestars.com.au.

Staying there

The Old Parkes Convent is a beautifully restored mansion, with apartments from $150. Phone 6862 5385; see parkesconvent.com.au.

Kadina Bed & Breakfast has two rooms in a spacious home. Rooms from $105. Phone 6862 3995; see kadinabnb.com.

More information

Visitors Discovery Centre, phone 6861 1777, see csiro.au/parkesdish. Parkes Visitor Information Centre, phone 1800 624 365; see www.parkes.nsw.gov.au.

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