US astronomers prepare to pour glass for giant telescope mirror

A furnace in Arizona is melting glass to pour a 27-foot mirror for a giant telescope with 10 times the resolution of the Hubble Space Telescope, scientists say. The mirror, destined for the Giant Magellan Telescope to go into operation in Chile's Atacama Desert by 2022, will take a full year to polish to within 1/20 the wavelength of light, a tolerance on the scale of about 1 in 10 billion, they said. "Let's imagine you took this mirror and you enlarged it to the physical size of the United States. The tallest mountain on that surface would be 1 inch tall," Michael Long of GMTO Corp., the non-profit organization based in Pasadena, Calif., that is coordinating the telescope project, told the Los Angeles Times. "So it's incredibly tight tolerances that have to be maintained, even when the mirror is in the telescope itself." The mirror is the third of an eventual seven that will be created at the University of Arizona's Steward Observatory Mirror Laboratory; one is complete and a second is in the polishing process. The seven mirrors will give the telescope an aperture of 80 feet, and the completed telescope will work in concert with existing and planned telescopes to study the universe, Long said. "We expect to be able to make observations and spectrographic studies of the first stars that formed after the Big Bang," he said. "We'll be able to observe the earliest galaxies, as those stars assembled, and answer the question, when did black holes arrive? Did they arrive with the early galaxies or did they arrive later?"