How does glass
chunk become a large telescope?
With the casting of its fifth giant mirror segment, the world’s largest telescope clears a major milestone toward completion.
While its mirror segments are in production (including a spare to be rotated into the mix during maintenance), construction of the facility that will house the telescope is underway at Las Campanas Observatory in the Atacama Desert in northern Chile. The GMT is one of only two projected next-generation instruments commonly referred to as extremely large telescopes that will be able to observe the entire southern skies.
With its unique configuration of seven honeycomb mirror segments, each spanning 27.5 feet, researchers say the GMT’s light-gathering capability will be unprecedented.
When the mirror lab started to produce the telescope’s first mirror, fabricating one with those specifications was widely deemed next to impossible. Led by the lab’s founder and director, professor Roger Angel, technicians and engineers perfected the process of producing the world’s largest, yet lightest, telescope mirrors in a process called spin casting.