By Lori Dugan
THATCHER — Eastern Arizona College’s Discovery Park Campus (EAC DPC) recently received a full-sized “Core Model” display for the “History of Astronomy Gallery” from the University of Arizona (UA).
“The display will be used in conjunction with our video presentation to help visitors better understand the equipment and processes used by the University of Arizona’s Steward Observatory Mirror Lab to fabricate world-leading telescope mirrors,” said EAC Discovery Park Campus Director Paul Anger.
The cores on display are an integral part of the pioneering spin-casting process designed by Dr. Roger P. Angel at the University of Arizona’s Steward Observatory Mirror Lab. The unique, hexagonal-shaped cores channel molten borosilicate glass (glass containing silica and boron trioxide) in a massive spinning oven to create the very ridged, yet lightweight, honey-comb design glass mirror of up to 8.4 meters (27.5 feet) in diameter. After a six-to nine-month process, the mirror blank is completed and tipped on its edge. The soft core material is then disintegrated using a high-pressure sprayer with soapy water, leaving only the hardened glass to begin the polishing process.
Because of the distinctive, hollow, honey-comb design, the mirrors are approximately 70% lighter than solid glass mirrors and are much easier to transport and mount in a telescope. They can also be quickly cooled to the surrounding air temperature to provide unprecedented use and imaging for telescopes. Made from a very lightweight compound called alumina-silica, the core material is soft and can easily be scratched or broken by a fingernail, yet is capable of withstanding temperatures in excess of 1150°C (2,100°F) during the glass melting process.
This unique design was used to create the ground-breaking 1.8 meter (5.9 feet) diameter mirror at the Mt. Graham International Observatory’s Vatican Advanced Technology Telescope (VATT), which offers the most exact mirror surfaces ever made for a ground-based telescope.
Eastern Arizona College’s Discovery Park Campus and the University of Arizona are partners in providing educational outreach visits to the three world-leading telescopes at the MGIO.
There is no charge to see the UA Core Model display in Discovery Park Campus’ History of Astronomy Gallery. Visitors can observe the 20” Tinsley Telescope in the Gov Aker Observatory or enjoy a thrilling “ride through the Solar System” on the Polaris shuttle simulator.
For more information on the educational outreach visits to the telescopes located at the MGIO contact EAC’s Discovery Park Campus at (928) 428-6260 or email discoverypark@eac.edu.
