Rancheros at the U of A Mirror Lab

Rancheros Don and Rebecca Williams overlook one of the glass bases being precision polished for the Giant Magellan Telescope.

Rancheros Don and Rebecca Williams overlook one of the glass bases being precision polished for the Giant Magellan Telescope.

Members of the Rancheros Square Dance Club and SaddleBrooke Square Dance Club took a day to enjoy a unique tour offered at the U of A Mirror Lab. This lab is the only place in the world to produce the giant 28’ diameter glass bases for some of the world’s finest telescopes. Right now, the lab is working on preparing precision glass bases for the Giant Magellan Telescope being assembled in Chili.

Each base is made of absolutely pure glass. The sand for this glass comes from a particular beach area in Florida. It is shipped to Japan where one of the only manufacturers able to produce glass that is absolutely free of any impurities prepares the glass. Impurities can harm the images the telescope is trying to capture. The prepared glass is smashed into five- to ten-pound chunks and delivered to the Mirror Lab where it is laid into the giant disc shaped oven by hand and heated to a very high temperature. The oven rotates at five rpm to maintain a delicate balance of the molten material and then cooled slowly over a three-month period to produce a base free of impurities and stable in structure so that it does not expand or contract with changes in temperature or pressure. The glass is then polished to a tolerance of millionths of an inch.

Transport of the giant discs is equally challenging. They will go overland in special containers to the port in Houston as they are too large to fit into an airplane. They will go by ship to Chili where they will be hauled up the mountain to the location of the Giant Magellan Telescope that is targeted to be open to “first light” in 2023. There will be seven discs, one in the center and six others surrounding it like petals of a flower. The aluminum reflective material is added to the surface only when the stable glass discs are in place. Stability of the underlying material is absolutely critical to assure light captured from distant stars is recorded at exactly the same place consistently and without any variation from expansion or contraction.

The Giant Magellan Telescope will be the largest in the southern hemisphere. Many stars in the southern hemisphere have yet to be mapped and the Milky Way Galaxy is also most visible from the southern hemisphere.

It was a very interesting and fun adventure for all. Tours of the lab are offered daily at 1:00 p.m. and 3:00 p.m. with a reservation. The lab is located under the U of A Football Stadium. It has a specialized suspension structure so it does not experience any vibration from cars, trucks or
football fans!