Mirrors For World’s Biggest Space Telescope Being Built In Tucson

By Tony Perkins
Published: Thursday, July 2, 2015 - 8:44am
Updated: Tuesday, December 15, 2015 - 2:06pm
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(Photo by Tony Perkins - KUAZ)
Engineers use machines to move mirror blanks, 40-ton foundations for the seven glass mirrors that will make up the Giant Magellan Telescope, scheduled to begin scanning the skies six years from now.

Exploring the universe from the ground begins with size. If you want to see far into space, you need a large telescope with big moving pieces. Some of the biggest pieces for what will be the largest telescopes on Earth are being built at the University of Arizona’s Mirror Lab.

Engineers use machines to move mirror blanks, 40-ton foundations for the seven glass mirrors that will make up the Giant Magellan Telescope, scheduled to begin scanning the skies six years from now.  

Each mirror, when completed, will measure up to 27 feet in diameter.  They’ll be arranged in a seven-story tall array on top of a mountain in Chile that’s 8,200 feet high.

Why does size matter when it comes to this kind of space exploration?

"Everything is big. The mirrors are big, the telescope is big, the structure it will be built on is big, the mountain it’s going to be placed on top of is big," said Chris Impey, deputy administrator and a researcher with the University of Arizona’s Department of Astronomy.     

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What are we going to learn using all of this big equipment on an Earth-bound telescope?

“Well, astronomers, even with the current generation of telescopes, eight to 10 meters, are still limited by light gathering power," Impey said. "So when we’re trying to look even further into the universe into the dawn of time, or when we’re trying to see planets around nearby stars, the more light-gathering power, the better.”

The bigger the mirrors, the more light-gathering power. Astronomers expect the Giant Magellan Telescope will see 10 times better than the Hubble Space Telescope, which is marking its 25th year in Earth orbit.

“With this new telescope we expect to get to within a few hundred-million years of the Big Bang.  So 95 to 98 percent of the age of the universe, and that’s so far back in time that’s when the first galaxies and stars formed, and we’ve never seen that epoch with any telescope, so that going to be very exciting to see, to see how the first galaxies and stars came into being," said Impey.

UA optical science researchers have helped put telescopes in remote locations around the world. The Giant Magellan Telescope will find its home atop a mountain in Chile’s Atacama Desert, a place best known recently for motorsport’s annual Dakar rally.

Buell Jannuzi heads the UA’s astronomy department, and he said the Giant Magellan is all about resolving some unanswered questions.

“The telescope, combined with state of the art instruments, allows us to make measurements that haven’t been possible before.”

The Giant Magellan Telescope is not the University of Arizona's project alone.  Space scientists in South Korea, Australia and Brazil — along with researchers at a half-dozen other universities — are joining forces to make it happen," Jannuzi said.

“It’s a group of many people coming together, and it’s that collaborative element that is so essential in doing really big, challenging science programs. It’s very hard for any one institution to do it by themselvesm," said Jannuzi.

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When astronomers look through the telescope, they’ll see a chance to prove some specific theories, like dark matter. Scientists think dark matter is a kind of glue that keeps galaxies from spinning apart.  

Dennis Zaritsky, who’s deputy director at the UA’s Steward Observatory, said the unseen force can only be detected by noticing its gravitational effects.

“The faintest, least luminous galaxies seem to have the most dark matter. So those are excellent test beds for dark matter theories, because they have so little normal matter, you know their dynamics are dominated by the dark matter," Zaritsky said. "So if you can measure the dark matter in those, that’s where the cleanest tests are, for different models of dark matter.”

But the astronomers admit that the Giant Magellan Telescope is just as likely to leave them with new questions about the universe.

“Because no matter what we observe or what we learn, it’s just more tempting to go and find out more about the subject, and I think that will be true with the Giant Magellan Telescope as it has been throughout history with all telescopes,” Zaritsky said.

Zaritsky said a popular joke among astronomers is that every successful research paper ends with the words “more data needed.” He thinks the discoveries coming from the Giant Magellan Telescope are likely to inspire those same words.

Science