Beyond Hubble

PHOTO COMPOSITE BY THE GEMINI OBSERVATORY
ALMOST HEAVEN: The dome of Gemini North sits perched under a brilliantly clear sky 14,000 ft. above sea level on Hawaii's Mauna Kea

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Adaptive-optics systems may sound complicated, but they pale beside another technological trick that will ultimately boost telescopes' power even more. Called interferometry, it achieves the precise focus of a truly huge telescope without actually having the thing built. Instead, light is combined from widely separated telescopes--the two Kecks, say, whose observatory building was designed with a basement-level chamber for that purpose, or two or more of the four VLT telescopes in Chile. The system is dauntingly tricky and complex, but its astonishing precision will let astronomers tease out the details of galactic structures and distant solar systems as never before.

Yet even this remarkable technology could become obsolete--along with the giant telescopes on Mauna Kea, Chile and everywhere else--if the grandiose plans of the world's astronomers come to pass over the next couple of decades. Telescope designers are already thinking about the next generation of ground-based supergiant telescopes, devices that will range in size from 30 m (100 ft.) across to a staggering 100 m, or 330 ft.--a telescope mirror wider than the length of a football field. These will probably be scaled-up versions of the Kecks, using hundreds of individual mirrors aligned to make a single giant that could have up to 100 times the Kecks' light-gathering power.

Armed with a new generation of adaptive-optics systems now under development, these futuristic scopes will once again revolutionize astronomy. "When we were planning for the Keck in the early days," recalls Caltech's Djorgovski, "we laid out some of the science we expected to do with it. And we were much too conservative: we missed most of the really important stuff we've actually found. I predict the same thing will happen with these enormous telescopes. We'll almost certainly find things we never could have imagined."