Wednesday, September 10, 2014

Giant Magellan Telescope: New Mega-Telescope in Chilean Andes

Artist's impression of the Giant Magellan Telescope's mirror system.

Credit: Giant Magellan Telescope /GMTO Corporation

A gigantic telescope designed to help astronomers solve some of the universe's deepest mysteries will soon start taking shape atop an arid mountain in the Chilean Andes.

The Giant Magellan Telescope (GMT) completed several major external reviews earlier this year and is on target to enter the construction phase before the end of 2014, project representatives said.

If all goes according to plan, the megascope should begin observing the heavens early in the next decade.

"The group here on the project is basically anticipating that we will begin construction activities late this year," GMT director Patrick McCarthy, Carnegie Observatories, told reporters.

"We're going ahead full steam, aiming for that 2021 first light when the first few mirrors get up on the mountain, along with all the rest of the hardware."

Scientists will use the enormous telescope to probe the nature of mysterious dark energy and dark matter, find and characterise exoplanets and study how the universe's first stars and galaxies came together, GMT representatives have said.

The Giant Magellan Telescope (GMT) will be built on Chile's Las Campanas Peak, at an altitude of about 8,500 feet (2,550 meters). The site was leveled by an excavation blast in March 2012.

GMT will arrange seven 27.6-foot-wide (8.4 m) primary mirrors, the biggest single-piece astronomical mirrors ever made, into one light-collecting surface 80 feet (24 m) across.

The completed scope will have 10 times the resolving power of NASA's iconic Hubble Space Telescope, project representatives say.

The third primary mirror for the Giant Magellan Telescope (GMT) is cast in a spinning furnace at the University of Arizona's Steward Observatory Mirror Lab on Aug. 23, 2013.

Credit: Mike Wall/

The GMT design also incorporates seven smaller secondary mirrors, which will change shape to counter the blurring effects of Earth's thick atmosphere.

Each of GMT's 20-ton primary mirrors must be shaped and smoothed to near perfection. Their surfaces cannot be off by more than 20 nanometers, about the width of a single glass molecule.

Adding to the difficulty is the fact that six of the mirrors must be steeply curved, since they surround a central (symmetric) mirror.

Manufacturing and polishing the primary mirrors, activities that are done at the University of Arizona's Steward Observatory Mirror Lab, have proved to be enormously challenging, McCarthy said.

But one of the big mirrors is finished, while two others have already been cast. Casting of the fourth one is scheduled for next March.

"So we've dealt with that as our principal technical risk, and we've retired that," McCarthy said.

Fundraising is another challenge. The project's total cost is pegged at $860 million, though perhaps another $100 million will eventually be needed to cover contingencies and the cost of inflation, McCarthy said.

The money will be provided by GMT's many partners, which include educational institutions such as the University of Arizona, Harvard and the University of Chicago, private organizations like the Carnegie Institution for Science and international entities, such as the state of Sao Paulo in Brazil.

Money is now coming in "at a rate that makes us pretty confident that we'll manage to raise enough funds to keep the project on schedule, and that the schedule will be set by the engineering rather than by how fast we can raise money," McCarthy said.

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