Nation & World News

Tons Of Molten Glass Go Into Making Mirror For Giant Telescope

By Scott Neuman on August 24th, 2013

Technicians on Saturday are set to cast 20 tons of glass for the third of seven ultra-precise primary mirrors that will make up the 72-foot Giant Magellan Telescope, scheduled for completion in northern Chile’s arid Atacama Desert in 2020.

The parabolic mirror will be cast at the University of Arizona’s Steward Observatory Mirror Lab. The molten borosilicate, made by the Ohara Corporation, will be spun cast at 2140 degrees Fahrenheit.

Describing the production of the first such mirror in 2005, the Lab explained the process:

The glass was “… melted in a rotating furnace until it flowed into a honeycomb mold. Once the glass had cooled and the mold material was removed, scientists at the lab used a series of fine abrasives to polish the mirror, checking its figure regularly using a number of precision optical tests.”

How precise?

Once the mirror cools, and the polishing complete — a process that is expected to take a year — it will be accurate to within 1/20 the wavelength of light, or put another way, “one part in 10 billion in terms of precision manufacturing,” according to Patrick McCarthy, the project’s director.

When finished, the telescope — which includes another seven smaller mirrors to direct the collected light to a focal plane — will employ adaptive optics to compensate for atmospheric disturbances that might otherwise blur the image. The GMT is expected to offer 10 times the resolution as the Hubble Space Telescope.

“We have to make this optic precise enough so that when the light travels five, 10 billion light years and comes and hits our telescope that we don’t scramble and lose that information that’s traveled for so long,” McCarthy says in the video below describing the mirror-making process.

Scientists hope the new telescope will give them a better look at super-massive black holes that are believed to be at the heart of most large galaxies and to detect and characterize new planets outside our solar system.

“Astronomical discovery has always been paced by the power of available telescopes and imaging technology,” said Peter Strittmatter, head of the Steward Observatory’s astronomy department, in a press statement, according to SPACE.com. “The GMT allows another major step forward in both sensitivity and image sharpness.”

Copyright 2013 NPR. To see more, visit http://www.npr.org/.

This entry was posted in News from NPR. Bookmark the permalink.

Comments are closed.

 

More Stories in News from NPR

Pope Francis opens the morning session of a two-week synod on family issues at the Vatican, on Saturday.

Vatican Bishops Scrap Opening To Gays, Divorced Members

Earlier this week an interim summary of the synod on family issues included conciliatory language on gays and on the taking of holy communion for divorced church members.


An artist's rendering of the flyby with Mars orbiters taking cover. Note that the image says "spacecraft not to scale."

Mars Probes Give Scientists Box Seats For Rare Comet Flyby

A “mountain-sized” comet known as Siding Spring will pass very close to the red planet, where orbiters from the U.S., Europe and India, hope to get close – but not too close — to the action.


Pro-democracy protesters set up new barricades after riot police retreated from a main road at Mong Kok shopping district in Hong Kong early Saturday.

Hong Kong Activists Clash With Police, Retake Protest Site

Pro-democracy protesters have replaced barricades in the congested Mong Kong district of the city hours after authorities dismantled the obstacles.


People stand on the island's south shore to feel the winds from approaching Hurricane Gonzalo, in Astwood Park, Bermuda on Friday. The storm has knocked out power to half of the residents of the British island territory.

Hurricane Gonzalo Hits Bermuda; Ana To Skirt Past Hawaii

In the British island territory, Gonzalo has wiped out power to roughly half of the island’s 70,000 inhabitants.


The Supreme Court early Saturday declined to block a Texas Voter ID law for the November election.

Supreme Court Lets Texas Enforce Voter ID Law For Nov. Election

With three justices dissenting, the high court’s ruling effectively blocks a lower federal court decision declaring the law restrictive and unconstitutional.


Thank you for your support

WUFT depends on the support of our community — people like you — to help us continue to provide quality programming to North Central Florida.
Become a Sustainer
I want to support FM 89.1/NPR
I want to support Florida's 5/PBS
Donate a Vehicle
Day Sponsorship Payments
Underwriting Payments