Eyes to the skies getting bigger and bigger

Two new technologies enable this extraordinary quest — one reliant on modern lasers and computing power and the other inspired by ancient Greek and Roman tilework.

The first is adaptive optics. It allows telescopes on the ground to get rid of the distortion caused when looking through Earth's thick atmosphere into space.

Adaptive optics relies on a laser to create an artificial star, or a constellation of fake stars, in the sky. Astronomers then examine the fake stars and use computers to calculate how much atmospheric distortion there is at any given time. Then they adjust the mirrors to compensate like a pair of eyeglasses. This adjustment happens automatically hundreds of times per second.

Adaptive optics worked first for smaller telescopes. But getting it to work for big observatories was a problem. The first successful use in large telescopes was in 2003 at the twin-telescope Keck Observatory in Hawaii, an effort that took nine years.

The second breakthrough involves technology that makes bigger mirrors possible. Instead of casting a giant mirror in one piece, which is difficult and limits size, astronomers now make smaller mirror segments and piece them together.

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Keck scientist Jerry Nelson, now working on the Thirty Meter Telescope, pioneered this technique and said he got the idea from looking at how the Greeks and Romans tiled their baths. This technique is going from 36 segments in current telescopes to 492 segments with his new project.

In astronomy, the bigger the mirror, the greater the amount of light that can be grabbed from the universe. For the past decade and a half, the Keck has had the largest Earth-bound telescopes, with mirrors nearly 33 feet in diameter.

However, three giant land observatories, proposed for construction within the decade, are going to dwarf those:

— The Giant Magellan Telescope. A partnership of six U.S. universities, an Australian college, the Smithsonian Astrophysical Observatory and the Carnegie Institution of Washington will place the telescope in Las Campanas, Chile, around 2016. The plan is for an 80-foot mirror. The cost is around $500 million.

— The Thirty Meter Telescope. The California Institute of Technology, the University of California and the Association of Canadian Universities for Research in Astronomy are aiming for a telescope with about a 98-foot mirror by 2018. No site has been chosen. The cost is about $780 million.

— The European Extremely Large Telescope. A partnership of European countries called the European Southern Observatory already has telescopes in Chile and is aiming for a new one with a mirror of 138 feet, scaled back from initial plans of 328 feet. The Europeans are aiming for a 2018 completion, but have not chosen a specific location yet. The cost would be $1.17 billion.

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