In a spectacular display of science, technology and imaginative innovation, a balloon will blow up into a three-story tall planetarium at the Evansville Museum.
If all goes according to schedule, the dome for a new immersive planetarium and auditorium will take shape in a matter of hours sometime Tuesday inside the framed-in skeleton for the museum's new entrance addition.
A pair of industrial blowers will inflate a 60-mil, two-ton fabric membrane that will balloon into what looks like the top half of a sunken globe, stretching to about 65 feet wide and about 36 feet tall. It will arise in the western half of the new museum entrance, under construction on the south end of the building.
The membrane, made of a tough, weather-impermeable material, will serve as the airform for the dome, which will be built from the inside by workers entering through an airlock door, explained Tom Dixon, project superintendent for Dome Technology of Idaho Falls, Idaho.
Using the company's patented technology, the team will begin by spraying 1½ inches of polyurethane foam inside the dome balloon. When that hardens, they'll form and fasten a skeleton of ½-inch steel rebar to the dome, then spray 5 inches of concrete slurry, called shotcrete, inside of that.
All of that should take about five weeks, said Dixon. During that time, the museum has invited engineering students from both of Evansville's universities to come see the process, developed by Dome Technology in the 1970s.
Since then the company has used the airform technique to build nearly 600 monolithic concrete structures around the world, said Dixon. At 65 feet in diameter, the immersive planetarium is one of the smallest he's worked on, he said.
The company has used the dome technology to build schools and churches more than 100 feet in diameter, and storage structures up to 256 feet across and 127 feet tall.
Once the museum's dome is finished, fans and other equipment will come out, setting the stage for the completion of the immersive auditorium.
More insulation, ductwork and other equipment will go between the steel-reinforced concrete bubble and the dome-shaped screen that will wrap around the audience in the auditorium, said Jeff Williams, project manager for Danco Construction, general contractor for the project.
Add a layer of terra cotta tile to its exterior, and the distance between the inside screen and the exterior tile surface should measure about 4 feet, said Williams.
Once fully outfitted, the immersive auditorium will reach 40 feet in diameter with seating for 68. Two digital projectors will cover the 360-degree dome with seamless moving images.
The new entrance and immersive planetarium theater are part of the final phase of a $14.1 million expansion begun several years ago.
Plans call for the new entrance hall and the immersive auditorium to open in January 2014, said Mary Bower, the museum's interim director.
For more on the planetarium and the new entrance plans, click on the "Reaching for the stars" link at emuseum.org online.
For more on Dome Technology, visit www.dometech.com.
Need Help? Call us at 1-877-304-7771.
Monday-Friday: 6am-5pm / Saturday: 6am-11am / Sunday: 7am-Noon