But the idea worked: as evidence, Freedman points to the twin Magellan Telescopes, precursors of the GMT equipped with two Angel-baked mirrors cast a decade ago and now operating on an Andean mountaintop in Chile. "These are the best natural imaging telescopes in the world, bar none," she avers. Making such mirrors is sufficiently complicated, however, that the Arizona mirror lab is still the only outfit in the world that does it at large sizes.

Although the GMT has high-profile partners backing it--including the Carnegie Institution, the Harvard-Smithsonian Center for Astrophysics and five major universities--it competes with several other mega-telescopes for funding. Two of the competing proposals would scale up the Keck's segmented mirror design. Caltech and others want to build one 30 meters in diameter. The European Southern Observatory is working out plans for a 1.2-billion-euro, 100-meter observatory that it has dubbed the OWL, for Overwhelmingly Large Telescope.

"It may come to a shootout, with only one getting funded," Angel says. To get a foot in the door, GMT proponents opted to spend nearly all their $20 million start-up money on this first off-axis mirror. "All the other groups who are thinking about building really big telescopes are still writing talking points," he observes. "We're the first to do something about it."

With this hurdle nearly cleared, Angel is already turning his attention elsewhere. "By the time things get into the planning stage, Roger has already moved on to the next exciting thing," Freedman notes. "He's just full of ideas that have revolutionized how telescopes are being built." Those ideas now include designs for large telescopes in deep space and at the poles of Earth and the moon.

In recent papers, Angel has touted a plateau in central Antarctica at an altitude of 3,300 meters, called Dome C, as a near-ideal observing site. "At Dome C, every quality factor important for ground-based astronomy is better by a factor of two or more than at any other spot on the planet," he enthuses. The polar base completed there last year has on average the least wind, the lowest temperatures, and the driest air of any human outpost. Although the National Science Foundation recently rejected a proposal to construct a two-meter telescope in Antarctica, Angel continues to push the idea. "A 100-meter telescope there could rival the best you could do in space," he argues.

Of course, space has its allure as well. Angel has analyzed the advantages of a 20-meter lunar telescope built in a crater near the moon's south pole by using a spinning pool of reflective liquid as a mirror. "The idea of installing something on the moon makes most astronomers nervous, because it means being the tail on a very large dog," he acknowledges. But by staring for long periods at the same patch of sky above it, such a telescope could peer to the very edges of the visible universe.

Even if the Giant Magellan Telescope finds funding, it is unlikely to see its first light before the middle of the next decade. At age 64, Angel has little hope of living to see any of his more ambitious designs completed. But that doesn't bother him. "It's like building cathedrals," he says. "You can't set the criterion of wanting to see it finished in your lifetime."

This article was originally published with the title Breaking the Mold.

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