Space


Vehicle Assembly Building / VAB

One of the world's largest buildings by volume, the VAB covers eight acres. It is 525 feet tall, 716 feet long, and 518 feet wide. It is divided by a transfer aisle running north and south that connects and transects four high bays. Facing east toward the launch pads are bays 1 and 3, used for the vertical assembly of Space Shuttle vehicles. On the west side of the VAB are Bays 2 and 4, used for flight hardware and orbiter storage.

From the OPF, the Shuttle Orbiter is rolled over to the Vehicle Assembly Building (VAB). Rollover generally occurs using the 76-wheel Orbiter Transfer System. The Shuttle Orbiter enters the VAB transfer aisle through the large door at the north end of facility. While in the transfer aisle, the orbiter is raised to a vertical position via 250- and 175-ton cranes. It is then lifted several hundred feet above the VAB floor and slowly lowered beside the waiting external tank and twin solid rocket boosters located in bay 1.

The external tank and solid rocket boosters already have been stacked atop the mobile launcher platform (MLP). Now the Shuttle Orbiter is lowered beside the external tank and mated to the stack. Once the Shuttle Orbiter is bolted to the external tank, the erection slings and load beams are removed. Extendable platforms, modified to fit Space Shuttle configuration, move in around Discovery to provide access for integration and final testing. Electrical and mechanical verification of the mated inter-faces is performed; a shuttle interface test verifies Discovery's interfaces and vehicle-to-ground interfaces are working. Umbilical ordnance devices are installed (but not electrically connected until the Shuttle Orbiter is at the pad). After six days, checkout is complete. Service platforms are retracted, and the VAB doors are opened to permit the tracked crawler-transporter vehicle to move under the MLP and the assembled Space Shuttle vehicle. The transporter lifts the MLP off its pedestals and onto the crawler-transporter, and the rollout to the launch pad begins. Two crawler-transporters are available for use at KSC.

The KSC of the 21st century began life in the early 1960s when new facilities were needed to launch the moon-bound Saturn V rockets. Initial plans called for a launch complex comprising a vertical assembly building (VAB), a launcher-transporter, an arming area, and launch pad. The VAB would consist of assembly bay areas for each of the stages, with a high bay unit approximately 110 meters in height for final assembly and checkout of the vehicle. Buildings adjacent to the VAB would house the Apollo spacecraft and the launch control center. Foremost in the construction timeline was the Vertical Assembly Building, as it was originally named. The $23.5 million contract called for more than 45,000 metric tons of structural steel and the erection of the skeleton skeleton framework of the VAB by Dec. 1, 1964. Construction of the massive building on sandy soil was one of the early design problems. The solution was to drive thousands of piles, steel pipes 41 centimeters in diameter, through the subsoil until they rested on bedrock more than 150 feet below the surface. These would not only anchor the building but also prevent the structure from sinking into the ground. That solution, however, created another issue. The building stood only a few feet above sea level and near the ocean. Salt water, saturating the subsoil, reacted with the steel piling to create an electrical current. To prevent this electrolytic process from gradually eating away the steel pipe, the pilings were grounded by weld-ing thick copper wire to each one and connecting the wires to the steel reinforcing bars in the concrete floor slab. Until this was done, the VAB could be said to be the world's largest wet cell battery. The pipe for the piling came in 16.8-meter lengths, and welders had to join three and sometimes four lengths of pipe together to make up a single pile. To speed the work, workmen welded at night, then drove the piles, which required better visibility, during the day. At the peak of activity, 10 pile drivers were in action. Three of them were new, electrically driven, vibratory drivers. When the piles reached the first thin stratum of limestone at about 36 meters, steam- or diesel-driven pile drivers took over and pounded the piles into the bedrock, which ranged from 151 feet to 171 feet (46 to 52 meters) below the sandy surface. Next, the forms were erected and the reinforcing bars for the concrete pile caps placed to bond the piles electrically to the reinforcing bars. From the air, the VAB foundation would resemble an underground honeycomb with the concrete pile caps dividing the site into cells or boxes. As soon as the concrete had set in a series of the pile caps, workmen removed the forms. Then they poured a layer of crushed aggregate into the boxes and poured the asphalt and concrete floor slab on top of the aggregate. Eventually 41,776 cubic yards (38,200 cubic meters) of concrete were poured for pile caps and floor slab before the foundation was completed in May 1964. With steel column sections and other structural steel arriving at the job site, erection of the framework began in January 1964 in the low bay area. By this time the original contract date for completing the structural steel (Dec. 1, 1964) had given way to a completion date of March 7, 1965. The job was a rather straightforward one although, because of the building's unique requirements, it appeared that the structure was being built wrong-side out. Because of the height of the assembly bay door openings - two on each side of the building - the horizontal stiffening structure had to be installed on the interior of the building, parallel to the transfer aisle, rather than along the exterior sides. Another critical part of the construction was the addition of three cranes. A 175-ton crane with a hook height of about 50 meters would run the length of the building and would traverse both the low bay and high bay areas above the transfer aisle. Two other cranes, with a 250-ton capacity and hook height of approximately 140 meters, would be capable of movement from an assembly bay on the opposite side. Although bridge cranes of this capacity are not unusual in heavy industry, there were unique requirements for precision, smoothness and control of their vertical and horizontal movement. The cranes would cost about $2,000,000. With its completion, NASA had a building so huge that "the Rose Bowl or the Yankee Stadium would fit on the roof."




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