Mar 5, 2021 - Science

A giant telescope is coming together

Miriam Kramer

A huge plate of dimly lit glass being placed into a furnace by a man in a white clean room suit — Preparing the glass for the mirror. Photo: Giant MagellanTelescope–GMTO Corporation

Scientists started on Friday casting one of the largest telescope mirrors ever made on Earth for the Giant Magellan Telescope being built in Chile.

Why it matters: The huge telescope is designed to one day peer into the atmospheres of potentially habitable planets around far-off stars, learn more about early galaxies and study other objects of interest.

What's happening: The mirror is being crafted in Arizona using the only spinning furnace in the world designed for this kind of casting.

On Saturday, the furnace will hit "high fire," spinning at five revolutions per minute and heating the glass to 2,129 degrees Fahrenheit for about five hours to liquify it.
After that peak in heating, the glass will gradually cool for about a month while the furnace spins more slowly, eventually reaching room temperature about 2.5 months after high fire.
"Once cooled, the mirror will be polished for two years before reaching an optical surface precision of less than one thousandth of the width of a human hair or five times smaller than a single coronavirus particle," the GMT organization wrote in a press release.

What's next: The GMT's first two mirrors are ready and in storage, with three others still in process. The seventh — and last — mirror is scheduled to be cast in 2023.

The team behind the telescope is also planning on crafting an eighth mirror as a spare.
The telescope is expected to see first light in 2029.

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A giant telescope is coming together

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