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    The Giant Magellan Telescope Will Capture Earth-Sized Planets and the Earliest Stars

    Written by

    Becky Ferreira


    Images: GMTO.org

    It was a busy weekend at the Steward Observatory Mirror Lab. On Saturday, the lab's technicians cast 20 tons of molten glass into an ultra-precise parabolic mirror—the third of seven. By 2020, the mirrors will have been transported to Chile's arid Atacama Desert and assembled into the new kid on the cosmological block: the Giant Magellan Telescope.

    Using adaptive optics, an 80-foot aperture, and a honeycomb structure, the GMT will record deep space images 10 times sharper than the Hubble. It will be the highest resolution telescope ever made, and it won't even have to leave the planet.

    The GMT owes its high precision to its meticulously crafted design. The mirror cast over the weekend will require a full year of polishing until it is within 1/20 the wavelength of light. That's a light tolerance level of one part per billion. To get a sense of the scale, imagine the mirror is the size of the United States. The tallest mountain on the surface would be about an inch high. In short: these mirrors are the smoothest thing to grace the Earth since Robert Downey Jr. 

    The GMT's main innovation, however, is the use of adaptive optics to overcome atmospheric turbulence. The atmosphere significantly distorts light captured by terrestrial telescopes, especially compared with their orbital peers. To solve the problem, the GMT's secondary mirrors will be fitted with actuators programmed to adjust the flexible, shapeshifting mirrors to counteract turbulence.

    This will “transform twinkling stars into clear, steady points of light.” On top of that, the mirrors are cast in a honeycomb mould, dramatically reducing the overall weight of the array. The hollowed-out design is not only a matter of convenience: it also makes the mirrors easier to cool and thus less likely to distort images due to heat.

    The state-of-the-art design will allow scientists to peer back in time to observe the first stars ever forged. The project's director, Patrick McCarthy, said it “will allow us to look at giant black holes almost anywhere in the cosmos.” On smaller scales, the telescope's ability to block solar glare will make it the best bet for studying Earth-sized planets in unprecedented detail. Indeed, the GMT team hopes the telescope will capture signs of life on extrasolar planets. Sure, discovering alien life is the holy grail for every space scientist, but the GMT brings the possibility into sharper focus than ever before.