As one might expect, mirrors with a surface accuracy of 19 nanometers are a bit expensive, and so far, only one of the GMT’s mirrors has been completed.
Telescope mirror design is a complex business. The unique configuration of the GMT’s lenses takes the complexity up a notch. According to the GMT Organization, “The GMT has a unique design that offers several advantages. It is a segmented mirror telescope that employs seven of today's largest stiff monolith mirrors as segments. Six off-axis 8.4 meter...segments surround a central on-axis segment, forming a single optical surface with a collecting area of 24.5 meters, or 80 feet in diameter.”
In addition to bearing an uncanny resemblance to the Death Star laser dish, this configuration requires extra polishing and testing procedures that were developed specifically for the GMT at the University of Arizona’s Steward Observatory Mirror Lab, who presumably have more than enough free time to spend on this sort of thing.
Over the course of six and a half years, the first mirror was ground and polished to its final state. Today, the GMT’s second mirror has been cast, and its surface is being processed. Casting of the third mirror is planned for August of 2013, with the fourth mirror to follow a year later.
In the end, all of this masterful craftsmanship and design will allow astronomers to see deeper into space than ever before, with a resolution that is 10 times greater than the Hubble Space Telescope.
Watch Animation of the Construction of the GMT:
Image and Video Courtesy of GMTO.org