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Astronomers brave Antarctic weather for a clearer view

To be perched under pollution-free, open skies on the Antarctic Plateau 3.2km above sea level is a professional stargazer's dream, even if it is cold enough to freeze the blood.

Armed with a small telescope and a photometer to measure light intensity, Herve Trinquet of the University Astrophysics Laboratory in the southern French city of Nice gazes out on an unblemished celestial vault.

With other colleagues from France and Italy, Trinquet is assessing the optical qualities of the Antarctic sky.

It is part of the groundwork for the AstroConcordia Observatory, the toughest yet possibly the most rewarding place on the planet from which to view the cosmos.

At the Franco-Italian base of Concordia, also called Dome C, atmospheric turbulence that muddies the view from most other spots on the planet is reduced to a minimum.

"It's at a height of about 30m in winter, which is unique in the world," says Trinquet.

What's more, he adds, 90 percent of that turbulence is near ground level, rather than distributed in several different layers ascending toward the heavens.

Besides the purity of the atmosphere, Dome C is also well suited for an infrared telescope, which collects long-wave radiation emitted by faint celestial objects.

Djamel Mekarnia, who works for the French Center for Scientific Research's observatory on the Cote d'Azur is observing a star with a pair of 30cm optical telescopes, one on the ground, the other on a platform 8m high.

As the Antarctic summer subsides, Mekarnia has a telescope trained on the never-setting sun. In the looming winter, when night will descend for three months, he will target the Moon. Next year, he will power up by several magnitudes with a new telescope that he hopes will be able to detect planets outside the solar system.

Nearby, Italian teams are installing six telescopes.

Antarctica's forbiddingly hostile temperatures are both an advantage and an impediment.

Average temperatures ranging from minus 30oC in summer to minus 60oC in winter make for clear viewing due to lowered thermal emissions.

But they can also frost up the mirror in the telescopes and make for arduous working conditions. Contact lenses are banned, and just placing an ungloved hand on metal will cause frostbite.

The big goal is to build something called the Keops Project, a network of 36 telescopes with 1.5m mirrors that will be spaced evenly in a circle 1km across.

It could be in place next year, Trinquet says.
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