Elizabeth visits David and Stacy in February 2011

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On our visit to the Steward Observatory Mirror Laboratory at the University of Arizona, we had a terrific guide who explained the spin casting method used to make the Giant Magellan telescope’s 7 paraboloidal mirrors. The telescope, which will be assembled in Chile, is expected to be operational in 2018 at a cost of about US $600 million.

Unusual features of the process include constructing a mold of about 1,700 alumina-silica fiber hexagonal boxes which form the negative of the honeycomb structure. This honeycomb allows a large mirror to be much lighter and more quickly responsive to changes in air temperature, and to be stiff enough not to wobble in the wind. Chunks of Japanese-made borosilicate glass are carefully examined for imperfections, laid onto the mold, and heated using a rotating furnace which is lowered over the mold and glass. For an 8.4 meter mirror, more than 20 tons of glass melt into the mold which, after the glass cools, is flushed out using a high-pressure water spray.

The back surface is ground flat, then the front surface is ground to very specific measures. Finally the mirror is polished then aluminized. The first mirror took 6 years to complete, the second, 3 years. People at the lab are working to get the process down to one year.

The Tucson Gem and Mineral Showcase displays items from dealers, private collections, and museums worldwide. It started as a local exhibit in 1955 and has grown to attract an estimated 55,000 people during the two week show.

Stacy missed an opportunity to whisper “backpack” (indicating anything Elizabeth bought would be traveling home on her back) and Elizabeth bought a lovely chunk of fuchsite. The airport screener asked, “Is this your backpack?” “Yes.” “Do you have a rock in it?” “Yes.” Because of the show, a lot of rocks went through the scanners.

The Tucson Botanical Gardens have 17 specialty gardens within 2.5 acres. The gardens have developed as a horticultural center, sanctuary for birds, and a center for education.

At the captivating butterfly exhibit, Stacy was quite patient while David and Elizabeth took photo after photo after photo. The butterflies are shipped from tropical butterfly farms and shipped to Tucson as pupae. The gardens receive about 350 pupae a week.

The Gardens also feature a Wicked Plants exhibit noting the many plants with protective mechanisms which are hazardous to humans. At the end of our visit, we enjoyed quiet time in the Zen Garden.

When Stacy went to a scientific meeting in CA, David and Elizabeth enjoyed a picnic in the peaceful desert surroundings of the Saguaro National Park where saguaro, unique to the Sonoran Desert, and other plants and animals are protected. Then we walked on one of the many trails examining (and photographing) the desert. The cacti in the Park were not as freeze-damaged as those in Tucson which, out of respect, we avoided photographing.

Next we visited the Colossal Cave where, unfortunately, the bats had migrated south for the season. The dormant cave has an amazingly complex structure resembling (to Elizabeth) cactus bones. It’s an interesting place to explore - with a guide, lights, and CCC constructed pathways. More rigorous routes are available for the adventurous. If we’d only known beforehand.....

Along with more private activities (dining, education, relaxing), these outings provided a terrific weekend for a grateful Elizabeth.