Giant Telescopes of the Future

The astronomical version of Moore's law says that telescopes double in size every few decades. But today's designers think they can build a telescope three, five or even 10 times bigger within a decade

By Roberto Gilmozzi

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Some of my best moments at Paranal Observatory in Chile are at night when, after a day of work, I go up "on deck," as we call the platform that hosts the four eight-meter-wide telescopes of the Very Large Telescope project (VLT). It is magical: the vast expanse of starry sky above, the smooth movements of the domes, the politically incorrect pleasure of smoking a pipe, the dark desert barely visible in its outline against the faintly opalescent horizon. As I stand there admiring the VLT, the most advanced set of telescopes in the world, its four 430-ton machines silently rotating in a complex ballet with the heavens, I reflect on how fortunate I am to be involved in such an awesome project. It is an achievement that all of humanity shares in. Like the other great telescopes of our day, such as the Keck Observatory, Hubble Space Telescope and Very Large Array, the VLT embodies the highest technologies that our civilization has to offer. If you traced the genesis of each part, you would find that, ultimately, it took millions of people to bring it into this world.

But astronomers never rest. The VLT had no sooner been built than many of us began to think about its successors, telescopes whose main mirrors would measure 25, 30 or even 100 meters in diameter. One concept that I have been deeply involved in designing is a behemoth called OWL (for its keen night vision and for being overwhelmingly large) that would almost fill the whole Paranal deck with its 100-meter mirror.

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