Lowell Observatory proposed the idea for a next-generation research telescope in the late 1990s. In October 2003, Lowell announced a partnership with Discovery Communications to build the Discovery Channel Telescope, and in July 2005, Lowell and Discovery held a groundbreaking ceremony southwest of Flagstaff at the telescope site near Happy Jack.

Major progress on components of the telescope has been made ever since, including on the $11 million dome facility to house the telescope. The dome is 73 feet — or seven stories — tall, 66 feet in diameter, weighs 170 tons and encompasses 7,800 square feet.

These excerpts are from a recent conversation about the telescope dome with Heather Marshall, who has served as the mechanical engineer for Lowell Observatory's new world-class research telescope for about four years. The telescope's 13-foot-diameter mirror is due to arrive at Happy Jack early next year.

Q: What attracted you to work on the Discovery Channel Telescope?

Marshall: I thought that the mission of Lowell Observatory was really appealing since it combines scientific as well as educational aspects.

Q: What are some of the highlights for you during construction of the DCT dome?

A: The most exciting thing was being able to see things physically coming together - all the puzzle pieces fitting together. These are things that I'd seen in models and construction documents that took shape before my eyes. For example, the phase I could see the quickest changes in the dome was as the steel crews worked to get the framework all together. The octagonal shape and facets began to appear and you could really start to see what the dome was going to look like."

Q: Did you recently complete an inspection walk through of the DCT dome?

A: Yes, we just had an inspection with the architectural firm - a little "to-do" list - and we only found a few very minor things to repair. So, that means the dome to house the Discovery Channel Telescope is 99 percent done."

Q: What are the main rooms in the DCT dome?

A: There's a control room where astronomers and observers will sit and control the telescope and its instruments. The data collection happens next door to the control room in the computer equipment room. We also have an instrument workshop and an electrical equipment room. There is a bathroom, of course - that's very important when you're 45 minutes from town. There is a mezzanine floor, the level between all the occupied spaces and the observing level. The main function of the mezzanine is to provide a thermal buffer between the working spaces, which will be maintained at appropriate temperatures for people, and the observing area, which will be at ambient (exterior) temperature. There's also a top floor, which is the observing area where the telescope sits, and the receiving bay where a truck can unload an instrument, for example.

Q: What are some design elements of the DCT incorporated to help maximize astronomical seeing?

A: The main requirement for the dome is, of course, to protect the telescope. It needs to be water tight and thermally insulated for daytime or when the weather is bad. To enhance seeing - which is what astronomers call the ability to observe objects clearly - we have an aluminum finish on the outside of the dome. It has really good thermal properties at night. The aluminum finish we selected heats up more than a white-finished dome during the day, but at night it more closely tracks the ambient temperature.

The other thing we have done to improve the seeing is to install vent doors. They are 10-foot by 16-foot ventilating roll-up doors all around the dome. Those are used to flush away any heat the dome has accumulated during the day and also any heat that is generated by electronics inside the dome."

Q: Are these ventilation doors also an energy-efficient solution?

A: Yes. Some other telescope facilities use air conditioning during the day to keep the observing space cool. At Happy Jack, since we have very consistent southwest winds, we can take advantage of that instead of active, energy-intensive cooling.

Q: Why did Lowell Observatory work with local contractors on the DCT dome?

A: We selected Flagstaff-based BEC Southwest to build the dome because they had done a really good job on the earlier concrete and steel facility work that was finished in the fall of 2007. Almost all of our subcontractors were Arizona-based, and for the most part, northern Arizona companies. These include Northland Electric, based in Flagstaff; NAEM for some of the steel work, and they are based in Flagstaff; Laron, Inc., who did a really good job on the dome rollers and drive systems, based in Kingman; and the architect, M3 Engineering, based in Tucson.

In particular, I'd like to compliment the work of Kevin Bond and John James who worked as project managers for BEC Southwest. They have really done great work and a great job as evidenced by the fact we finished the dome ahead of schedule and under budget.

Steele Wotkyns is public relations manager for Lowell Observatory

On the Web

Visit: http://www.lowell.edu/dct/tour.php to see images of the Discovery Channel Telescope.