In a facility beneath the stands of Arizona Stadium at the University of Arizona in early March, a massive furnace began spinning to produce a one-of-a-kind mirror for a one-of-a-kind instrument. The Giant Magellan Telescope, currently under construction in Chile's Atacama Desert, is expected to have a resolving power 10 times greater than the Hubble Space Telescope when the GMT is commissioned in 2029. At the heart of the massive telescope is an array of seven individual mirror segments that will collectively form a primary mirror surface 25 meters in diameter. The university team is casting the sixth mirror, a process that involves melting nearly 20 tons of high-purity, low-expansion, borosilicate glass. As the glass melts, the spinning of the furnace forces the molten material up the sides of a mold to form a curved surface.
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