This week, the University of Arizona’s Steward Observatory Mirror Lab begins work on the sixth of the seven main mirror sections for the Giant Magellanic Telescope (GMT) .On March 1, the lab began heating a unique glass furnace at temperature. 1,165 ° C. That was a major achievement in a manufacturing process known as spinning casting. It took about four months to make a mold and another nine hours to cover with almost 90 tons of rare borosilicate glass.
On Friday, the stove started spinning at a speed of about five rpm. The combination of heat and motion forces the glass up the side of the mold as it melts, creating a curved surface. When casting the 8.4-meter glass over the weekend, it goes through a month-long “melting”; process wherein the furnace stops slowly as the glass cools. Finished to allow the glass to cool evenly, making the final product as tough and imperfect as possible. It will take another month and a half for the temperature to cool to room temperature. At that point, a long polishing process can begin.
It will take about four years to produce a single glass piece to complete. In 2019, the university completed the second GMT of the GMT, which is now stored for transport to Chile. Although the project started in 2015, it would not be completed until it was completed a decade later. But when this is done, the GMT can capture images 10 times clearer than those created by the Hubble Space Telescope.