Tucson Adventures

Our last blog post focused primarily on our adventures in the Tucson desert. We've moved on to northern Arizona, but wanted the opportunity to share some of the other things we did during our time in the Tucson area. Some of these were repeats of past experiences. Others were entirely new for us.

Mount Lemmon Skyway

This beautiful road travels 12 miles up from the valley floor to the summit of Mount Lemmon. The road has a number of pulloffs, offering spectacular views of Tucson. You pass through a number of climate zones on your way to the top (it snows up there in the winter, and there's even a ski area).

As you get higher, the vegetation changes from cactus and desert plants to pine forest.

Saguaro National Park

As you know, we love Saguaros! They even have their own emoji:🌵 The national park is in two distinct districts - one east of Tucson and the other west. The eastern district, called the Rincon District after the mountain it sits beneath, is flatter and more open.

A roadsign exhibit explained that, when the area was set aside in the 1930s, it contained the most dense and spectacular saguaro forest anywhere. However, many of the trees died off as time went on. It was only in the 1980s that the Park Service understood that young saguaros often grow under the protection of other trees and, by allowing these trees to grow and by stopping grazing in the area, the saguaros began a comeback that continues today.

A young saguaro growing under the cover of a bush.

The western Tucson Mountain District of the national park (so-called because it was carved out from Tucson Mountain Park in 1964) is hillier and, we think, more dramatic. It is also less visited than the Rincon District.

This view is from right behind the visitor center.

We hiked both the Valley View nature trail (with signs detailing many of the plants) and the Cactus Wren trail during our visits to the Tucson Mountain District.

The Cactus Wren trail (3.6 miles roundtrip) is in a flatter section of the park.

Bisbee

One day we drove about two hours southeast to the mining town of Bisbee. There we visited the Copper Queen mine, now closed except as a tourist attraction. It produced many thousands of tons of copper, silver, turquoise, and other minerals while it was active between 1877 and 1975. We rode a train into the mine for our tour, where we were told about the mine equipment that was used, and how the walls were blasted.

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Most of the minerals were concentrated in nodules, sometimes dozens of feet across. Wooden structures, which could be stacked in the openings, helped hold up the ceiling and allow the miners access for drilling.

On the way out of town, we passed by an enormous open-pit copper mine (now closed).

Madero Canyon

On a drive we took one day to the artist town of Tubac, we took a side trip into Madero Canyon in Coronado National Forest. We did not have time for hiking, but enjoyed the views back down the canyon from the end of the road.

St. Xavier del Bac Mission

Just south of Tucson is the St. Xavier Indian Reservation. We stopped by to see their mission church, which was built with the help of tribal members. Interestingly, there was not a cross on the otherwise ornate alter carvings at the front of the church.

Kitt Peak National Observatory

Kitt Peak is located about 40 miles west of Tucson, and is the only "national observatory" in the country, meaning that any astronomer or university can apply for telescope time. The peak was chosen due to the extremely dry air, desert climate, and proximity to Tucson, and the first telescope - at the time the largest sun-observing telescope in the world - was built in the late 1950s

Now, dozens of telescopes dot the mountaintop.

Each evening, Kitt Peak hosts a star program. We traveled there with friends from Desert Trails RV Park Kersten Goldschmidt and Stefan Eberhard.

We needed to arrive at the mountaintop before sunset. They served boxed sandwiches and gave a talk about the facilities and research going on at Kitt Peak.

After that, we walked around and, led by informative and entertaining astronomer guides, saw some of the telesopes from outside.

We watched the sun set over the distant mountains.

After dark, we divded into three groups and spent 30 minutes each at three different stations: (1) a tour of the constellations using laser pointers; (2) a chance to look at the night sky using binoculars; and (3) viewing Jupiter and its moons as well as a star cluster from the 30-inch telescope that sits above the visitor center. The sky was crystal clear and we had some great viewing.

At the end of the evening, we had to wait for an "all clear" to start our engines, turn on our headlights, and drive back down the mountain in a caravan, so as not to interfere with ongoing astronomy observations.

The Richard F. Caris Mirror Lab

Continuing our astronomy theme, we also took a tour of the Caris Mirror Lab at the University of Arizona. The Lab is the world's sole facility for making giant telescope mirrors, and has been doing this since the 1980s. After an initial presentation by some entertaining and knowledgable astronomy undergrads, we walked over to the casting facility, which sits next to Wildcats stadium. Why there? Because they needed two very substantial concrete walls to support the ceiling cranes that lift and move the mirrors from station to station, and the football stadium provided one ready-made wall.

The facility is in the middle of preparing seven 8.2 meter (27 foot) wide glass mirror blanks for the Giant Magellan Telescope which, when commissioned in Chile's Atacama Desert in the 2030s, will be 200 times more powerful than the largest telescopes operating today.

The small inset of a person on this model gives a feel for the size of the completed telescope.

Each mirror is cast on a giant, rotating plate (which was having some electrical repairs while we visited). A mold is set up on the plate, and many pieces of borosilicate (Pyrex) glass are dumped inside. A giant furnace lid closes over the mold, heating the glass to 2,000 degrees Fahrenheit. By rotating the furnace at around 15 mph, centrifugal force gives the melted glass the concave shape needed for the mirror. It can take up to two weeks for the mirror to cool down and aneal before it's removed from the furnace and moved to its next steps.

The mirror moves on to the polishing phase, which can take months.

This mirror is having its back side polished before it is flipped over to polish the front side. If you look closely, you can see hexagonal holes in the back of the glass, which make the mirror much more lightweight. The sold front surface will be about two inches thick when completed.

During the polishing phase, the mirror is moved back and forth, sometimes dozens of times, between the polishing station and this test tower, where laser beams are used to find imperfections in the surface. The mirror is polished to a tolerance of 25 nanometers.

Why 8.2 meter mirror diameters? Because that's the size that will fit through the underpasses of I-10, used to move mirrors from the lab to their distant telescopes.

The mirrored aluminum surface (about a soda can's worth of aluminum) is not applied until the mirrors are at their final location and ready to be installed. The surface lasts about 4-5 years before oxidation deteriorates the reflection. The old aluminum is removed, and a new surface installed.

Sabino Canyon

Toward the end of our visit, we visited the Sabino Canyon recreation area. Maintained by the U.S. Forest Service, the Canyon is a popular hiking and tourist spot northeast of the city center.

A 3.7-mile-long paved road leads up the canyon, rising about 700 feet over its length. We took an electric tram to the top of the road, and hiked back down to the visitor center. There were not many visitors and we often had the road to ourselves.

The road crosses back and forth over Sabino Creek. The water level was low during our visit. During past visits to Sabino Canyon, we've seen the creek washing over the road.

Despite the low water, bright green leaves were emerging on the trees near the creek. This is called a riparian landscape.

We were also able to see this blooming yucca.

We also caught this well-camouflaged roadrunner traveling next to us. We were not able to catch Wile E. Coyote, though.

Leaving the Tucson area, we traveled first to the Phoenix area and then into northern Arizona. More about those adventures in our next blog post.