Discovery Telescope Making Progress

Aug. 3, 2006 — Managers of a Discovery Channel-backed project to build an innovative and powerful telescope near Flagstaff, Ariz., have selected the University of Arizona's College of Optical Sciences to finish the observatory's 4.2-meter primary mirror.

Once operational in 2009 or 2010, the telescope will be one of the largest in the U.S. and have the unique ability to switch from wide-field imaging and surveying to focusing on more specific regions at greater distances.

The heart of the observatory is its primary mirror. Corning Inc. of Canton, N.Y., cast and fused the glass for the mirror last year. By the end of the month, the 6,700-pound blank will be sent to the University of Arizona for finishing work and polishing.

For the delicate and difficult observations planned for the telescope, the mirror's optical surface must be extremely precise. If the mirror were the size of the U.S., imperfections would have to be less than 1 inch high.

The blank, which is made of ultra-low expansion glass, is just 4 inches thick.

"The thinness of the mirror helps it cool rapidly at night, reducing heat waves that would blur the images," said project manager Byron Smith.

Engineers will take about 18 months to bond 120 structures, called pucks, to the mirror's convex backside. The support structure is needed to make sure the mirror does not flex during grinding and polishing.

Shaping the mirror should take another five months. Finally the team will spend up to 18 months on a final round of polishing to perfect the reflection surface to within a few millionths of an inch.

Discovery Communications is backing the $40 million project in partnership with the privately-owned Lowell Observatory, best known for the discovery of Pluto in 1930. The new telescope will be located 40 miles southeast of Flagstaff within the Mogollon Rim Ranger District of the Coconino National Forest.

The telescope will be used in several cutting-edge research programs, including the search for asteroids that may be on a collision course with Earth and studies of planets beyond our solar system.

Discovery Communications plans to use the observatory for real-time global broadcasting and educational programming about astronomy and science.