Chilean mountain to lose its top for European Extremely Large Telescope

PUBLISHED : Sunday, 22 June, 2014, 3:19am
UPDATED : Sunday, 22 June, 2014, 3:19am

The top is being lopped off the 3,000-metre Cerro Armazones in Chile to host the world's largest optical and infrared telescope.

Once the dust has settled and the rubble has been cleared, the mountain will be ready for the astronomers.

The European Extremely Large Telescope, or E-ELT, will serve astronomers and cosmologists for generations. About 2,500 tonnes of steel rigging are on order to hold a primary mirror nearly 40 metres wide, large enough to see the faintest light from the earliest stars, and pick up signs of life on planets far beyond our solar system.

"Today we cannot imagine what will be discovered," programme manager Roberto Tamai said. "I feel excited. We are opening a highway for the future knowledge of astronomy."

The telescope is the most ambitious project for the European Southern Observatory (ESO), a multinational organisation.

But first the jagged mountaintop needs to be broken apart and bulldozed to a plateau large and strong enough to hold the enormous observatory. Perched on top of the reshaped mountain, the €1.1 billion (HK$11.6 billion) E-ELT will have near-perfect conditions for scanning the heavens.

Cerro Armazones is not the first mountain to be decapitated in the area. About 20km away is Cerro Paranal. Engineers from the ESO cut that peak down to size some years back to build the Very Large Telescope.

More than half a million tonnes of rock will be removed from Cerro Armazones, leaving it 18 metres shorter.

Work in the desert can be a hard slog. The humidity is down to about 10 per cent, making the air extraordinarily dry.

The low humidity is not the only problem for the 100 or so ESO staff at Paranal. Dust gets everywhere, in your shoes, your glasses, your car. The desert hues, shades of pinky, orangey brown, are monotonous. People come to crave a view of the sea, and the green of plants, entirely absent from the desert.

Then there are those missing loved ones back home. "There's a lot of sacrifice. Your private life goes ga-ga," said Tamai.

The E-ELT will take a decade to build. The telescope's huge mirror is too large to make from one piece of glass, so engineers will combine 798 smaller hexagonal mirrors, each of which can be moved independently.

The E-ELT has a system called adaptive optics, which can shift the mirrors in real time to counteract the blurring effects of the atmosphere. "We need to be able to adjust each one to get the perfect shape for the primary mirror, and that has to happen at all times to get the best possible image quality," Liske said.

When the telescope is operational, around 2024, astronomers will point it at earth-like planets orbiting sun-like stars in faraway solar systems. So far, scientists have made only the most rudimentary measurements of these planets, but E-ELT could change all that.

"We want to study the atmospheres of planets that are just the right distance from their stars that life might form on their surfaces. The goal is to try to say whether life might exist on some of these planets," Liske said.

A planet's atmosphere can hold numerous signs of life. The E-ELT will look for infrared signatures of methane, released by much of life on earth, and other gases such as oxygen and carbon dioxide. The telescope could detect direct signs of life, such as chlorophyll found in vegetation.

The telescope will have many more uses, though many are not yet apparent. In 2011, scientists shared a Nobel prize for work on supernovae, or exploded stars, that revealed how fast the universe is expanding.

Isobel Hook, an astrophysicist at Oxford University who works on the E-ELT, hopes to use the telescope to observe more distant supernovae. "We'll be able to see supernovae much further away, and so map out the expansion of the universe to much earlier times," she said. "The E-ELT is really the next big step for astronomy everywhere."


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