John Martin, standing at left, rotates the mirror mold while Randy Lutz, center, and Phil Muir place glass pieces into position at the UA's Steward Observatory Mirror Laboratory. Nearly 26 tons of special borosilicate glass will go into the mold before the casting oven's switch is turned on.

jim davis / arizona daily star

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Every year or two, strange things happen under the east side of Arizona Stadium.

This cavernous building, the University of Arizona Steward Mirror Lab, is where you come if you want a mirror made for one of the world's largest powerful telescopes.

Monday morning the mirror lab crew started making the combined main and tertiary mirrors for the Large Synoptic Survey Telescope.

Dire Straits' "Money for Nothing" blasted on a radio while workers lying prone on a scaffold suspended over the mirror mold carefully set chunks of special Japanese borosilicate glass on the floor of the nearly 28-foot-diameter "cake pan." The 4- to 8-pound chunks of glass shimmered like ice cubes — waiting for a shot of scotch in a magazine ad.

By this afternoon they'll have put nearly 26 tons of the glass in the pan, centered in the 39-foot-diameter casting oven.

Sunday, after the oven's domed lid has been lowered over the pan, someone will throw a switch and the heating elements will slowly raise the temperature of the glass until it melts. It should reach 1,380 degrees Fahrenheit and turn liquid the night of March 28.

Then the entire 39-foot-diameter oven will begin to spin, about seven revolutions per minute, the exact speed needed to cause the melted glass to form the correct concave shape the main mirror will need for its wide-angle view of space.

Two huge Caterpillar diesel generators were hoisted into place outside the lab Monday morning to ensure a constant power supply during the casting.

Once the ideal shape has been obtained, the heat will be cut, and the mirror blank will slowly cool for about 100 days.

The UA lab has made a number of 8.4-meter mirrors, each technically tied for the title of largest in the world. But this one is different because the LSST's tertiary (third) mirror is being cast as part of the primary mirror. The 16-foot center of the mirror will be ground into a much steeper curvature.

The main, or primary, mirror will bounce light from the wide-angle view of space to the secondary mirror, which will send it back to the tertiary mirror in the middle of the primary mirror. The tertiary mirror then bounces that light, this time to a huge — almost 2 feet square — 3.2 billion-pixel digital camera chip in the middle of the secondary mirror.

The single casting is another brainstorm from UA astronomer and inventor Roger Angel, who dreamed up the lab's spinning honeycombed mirror system in the first place. The combined casting is supposed to save money and time, although the grinding and polishing will be complex. Typically, polishing of the mirrors takes well over a year.

The $400 million scope, to be located on a mountaintop in Chile, will scan and photograph the entire available night sky endlessly, moving every 40 seconds and snapping another 15-second exposure photo on the world's largest digital camera chip. It will cover the entire visible night sky every three nights. The short time lapse will allow astronomers to pick out short-term changes in space — something that appears where there was nothing just a few nights earlier.

LSST backers say it will excel at detecting potentially hazardous near-Earth objects, exploding supernovae and distant Kuiper Belt objects.

It also will cause problems, producing massive piles of images that will have to be stored and analyzed. Google signed on as a partner to help manage the anticipated flood of data — terabytes each night — from the LSST.

UA astronomer Phil Pinto, the university's technical liaison on the LSST, is already working on LSST simulations.

"My job is to figure out what would be useful to the largest number of people," Pinto said.

He said the anticipated massive power of the telescope is so far making it easy to please partner scientists.

The UA is one of 23 partners involved in the public-private, non-profit LSST Corp. The telescope, expected to be operative in 2012, is also funded by the National Science Foundation. The Charles Simonyi Fund for the Arts and Sciences and Microsoft founder Bill Gates combined to give $30 million to make the mirrors.

The UA and the University of Washington are LSST founding partners, along with the Tucson-based National Optical Astronomy Observatory and Research Corp. Former UA President John Schaefer has been instrumental, through his involvement with both LSST Corp. and Research Corp.

• Visit the UA's Steward Mirror Lab site: mirrorlab.as.arizona. edu.

• Visit the LSST site: www.lsst.org/ lsst_home.shtml.