Casting a $20 Million Mirror for the World’s Largest Telescope

The glass arcs that will let astronomers peer back millions of years is decades in the making

"Building a mirror for any giant telescope is no simple feat. The sheer size of the glass, the nanometer precision of its curves, its carefully calculated optics, and the adaptive software required to run it make this a task of herculean proportions. But the recent castings of the 15-metric ton, off-axis mirrors for the Giant Magellan Telescope (GMT) forced engineers to push the design and manufacturing process beyond all previous limits.

Building the GMT is not a task of years, but of decades. The Giant Magellan Telescope Organization (GMTO) and a team at the University of Arizona's Richard F. Caris Mirror Laboratory cast the first of seven mirrors back in 2005; they expect to complete...

The glass arcs that will let astronomers peer back millions of years is decades in the making

"Building a mirror for any giant telescope is no simple feat. The sheer size of the glass, the nanometer precision of its curves, its carefully calculated optics, and the adaptive software required to run it make this a task of herculean proportions. But the recent castings of the 15-metric ton, off-axis mirrors for the Giant Magellan Telescope (GMT) forced engineers to push the design and manufacturing process beyond all previous limits.

Building the GMT is not a task of years, but of decades. The Giant Magellan Telescope Organization (GMTO) and a team at the University of Arizona's Richard F. Caris Mirror Laboratory cast the first of seven mirrors back in 2005; they expect to complete construction of the telescope in 2025