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The service tower will neatly unite with the Shuttle Assembly Building, a structure that will be 250 ft. high and weigh 3,000 tons when it reaches completion in late 1984. Approaching the launch pad from a direction opposite to the service tower, it will neatly "mate," as the engineers like to put it, with the other building to form an enclosed, weather-protected space where the rest of the shuttle vehicle can be assembled. Like the tower, the assembly building will have a crane in its roof. Together the two machines can hoist the empty, 154.4-ft.-long, 69,000-lb. external tank of a future shuttle into place between the stacks of rocket boosters. Clearance on each side: less than ¼ in. The final element in the assembly, the main body of the shuttle, or orbiter, is mounted on the external tank by means of a double crane.
The Shuttle Assembly Building was not part of the original design of the Vandenberg launch pad. Early plans called for vehicle assembly to take place in the semienclosed environment of the service tower, with the tower's crane and a second device, called a strongback, attached to the Launch Mount Tower, to perform all the hoisting. The system called for a tolerance limit of as much as ¼ in. in fitting the orbiter to the tank. NASA said no, setting the maximum permissible degree of variation at a minuscule ³¹/iooo³¹∕¹ººº in. "With the wind and the weather at Slick Six, we knew we could never get it down to that," says Major Ronald L. Peck, Vandenberg's chief of public affairs. "So they went back to the drawing boards and came up with the Shuttle Assembly Building. We call it our $40 million one-sixteenth of an inch."
That expensive steel-and-sheet-metal postscript, the assembly building, shelters the newly assembled spacecraft until it is ready for loading. The job begins in a hulking concrete structure called the Payload Preparation Center, a stationary, 147-ft-high building. There, in a relatively particle-free chamber, the spy satellites and other exotic space gear to be carried aloft will be given final checks in sealed chambers. Explains Engineer O'Gorman: "If we do the job right you should be able to take a transistor radio in there and not pick up a single outside signal." This feature is designed to prevent accidental interference during testing and, obviously, to prevent unauthorized monitoring of electronic transmissions.
Unlike the cargo on current flights, Vandenberg payloads such as meteorological and navigational satellites will not have to be placed in bulky canisters to keep them free of contamination. Instead the devices will be taken into the Payload Changeout Room, Slick Six's third movable building. This 158-ft.-high, 6,000-ton structure moves by rail toward the waiting assembly building, where a mammoth door of six panels, each measuring 30 ft. high and 130 ft. wide, will slowly rise, just like a garage door. Inside the building-within-a-building, the payload will be lifted into the orbiter's cargo bay and secured in niches that are custom designed for each piece of space baggage.