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The Daily Wildcat

The Daily Wildcat


UA staff works on third mirror for Giant Magellan Telescope

Mylo Erickson
Mylo Erickson / Arizona Daily Wildcat The Mirror Lab located below Bear Down Field makes mirrors for large telescopes around the world.

After casting the second of seven mirrors for the Giant Magellan Telescope in January, the UA GMT staff are steadily casting the third and zooming in on a new perspective on the universe.

The Steward Observatory Mirror Lab is home to the construction of the GMT, which “will be one of the next class of super giant earth-based telescopes that promises to revolutionize our view and understanding of the universe,” according to the GMT website. The telescope will have a resolving power 10 times greater than the Hubble Space Telescope.

Although developed in the mirror lab, the assembled telescope, which is expected to be finished in 2018, will be transported to and operated at Las Campanas peak, Chile, due to the area’s altitude and lack of air pollution.

Some scientists said they hope this new technology will help to answer ageless questions about our surrounding universe, as well as to create new ones.

“It’s really an exciting time in astronomy right now,” said Philip Hinz, a member of the GMT scientific advisory committee. “The tools are still advancing fast enough where you know you can make a lot of surprising discoveries ahead of what people might even think was out there.”

The seven 27-foot monolith mirrors composing the telescope are the world’s largest spun-cast mirrors, the first of which was cast, ground, polished and completed in October 2012. Before the accomplishment of this “milestone,” according to Buddy Martin, a polishing scientist at the mirror lab, scientists had to overcome several unforeseen difficulties that caused construction to last longer than expected.

However, the process has since increased in efficiency.

Martin said he believes mirrors will now be cast at around 1-year intervals, with the third segment being cast in August.

“These mirrors are different from anything we’ve made, different from anything anyone’s ever made,” Martin added.

Six of the mirrors composing the telescope are off-axis segments, which border a central on-axis segment. Together, the mirrors resemble a “flower petal” or “Pringles potato chip,” according to staff members. Due to this distinct shape, each mirror must be polished in a unique manner to funnel light from space by striking the mirrors to secondary mirrors, then below to the primary central mirror, where cameras use the light to determine how far away objects are.

“It’s not just seeing a little dot of light, it’s seeing the chemical evidence for life, and we have that possibility with these bigger telescopes,” said Roger Angel, scientific director of the mirror lab.

Martin said the magnification will create new possibilities for the GMT.

“It’ll allow astronomers to study galaxies that are more distant than anything that’s been studied,” Martin said. “When you look at something more distant, you’re looking back in time, because the light takes billions of years to get to us.”

While the legacy of GMT’s current and future discoveries can only be guessed, Dennis Zaritsky, deputy director of the mirror lab, predicts they will have a large impact.

“It really is the new generation,” Zaritsky said. “It’s going to take 10 years to be ready, and then it’ll be the world’s leading telescope for the next couple decades, so it really is a project for the coming generation.”

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