Mousellaneous
Spaceship Earth 101: Solving the Triangle Dilemma
By Steve Langlois and Greg Dorf, Epcot Discovery Center
February 15, 1996
Spaceship Earth is more than the visual symbol of Epcot and part of the Walt Disney World Resort skyline. It fulfills a dream set forth by Walt Disney, that American ingenuity and technology can move our society into the future.Yet beyond the dynamic achievements made by designers and Imagineers for this architectural marvel is a question which has occupied the minds of our guests, fellow Cast Members, and people all over the world:
How many triangles (meaning the individual silver facets) are on Spaceship Earth?
The answer is 11,324. Strangely enough, the final number was never tabulated during the construction phase. A variety of guesses and estimates have been suggested, but without real verification.
Spaceship Earth took two years and two months to build (the design process alone took 14 months). First, over one hundred 14-inch diameter concrete-filled steel piles were driven into the ground to depths between 120 and 150 feet. These pilings became the foundation for the three pairs of legs which would support Spaceship Earth.
The geosphere's design required no scaffolding or temporary support during construction. Adjustable support beams, called quadrupods, were attached to the sides of a hexagonal platform resting on the six legs. This platform serves the attraction as a maintenance facility (the entire ride structure is constructed on top of it). Struts were attached to the quadrupods and to each other in circumferential rings.
A pre-constructed 50-foot diameter top was eventually hoisted into position to complete the upper portion of the sphere. Then workers assembled the bottom portion underneath the support legs.
Spaceship Earth is actually two separate spherical structures, one inside the other. The inner sphere was created by the structural steel rings to form the sphere's shape, and then enclosed with 954 fluted closure panels. The panels were rubber-coated to seal and waterproof the structure.
The silver triangle-covered shell on the outside is just a facade for the inner sphere. The facade is held in place two feet away from the inner sphere by 467 four-inch aluminum pipes called stand offs.
Now imagine Spaceship Earth hovering in the air, without the ride tubes or legs to support it. Taking into account that the sphere is based on 12 pentagons, and each pentagon is divided into 80 triangles, it would take 960 triangular structural panels to cover the inner sphere completely. Each panel is hidden by a corresponding facade of four pyramids. Each pyramid consists of 12 individual triangular facets, meaning the entire outer sphere would have 11,520 silver facets (960 x 4 x 3). But because of the ride tubes, six full panels were eliminated.
To find the total number of triangular facets, an Epcot Discovery Center representative took the known geometrical configuration and walked around the sphere to find out how many of the facets were affected by the legs and other structures. Verifying these with blueprints obtained from Walt Disney Imagineering, it was a simple matter of subtraction to find the total number of facets remaining.
Ever since Spaceship Earth opened, guesses and estimates have been traded by friends and families as they walk by the attraction. Now, thanks to a little geometry and sharp eyes, the Spaceship Earth "triangle" dilemma is no more.
