The shuttle service and access tower SSAT is assembled at Launch Complex 39A from sections of launch umbilical tower 3.

At the Kennedy Space Center in Florida, the shuttle service and access tower SSAT, left, is assembled at Launch Complex 39A from sections of launch umbilical tower 3. The lower 180 feet of the old ML-3 will be topped by the former uppermost section on which a hammerhead crane will be installed and the next lower section which houses the intact ML-3 elevator room and equipment. The SSAT will anchor and support a hinge column to the Payload Changeout Room PCR which will travel on a rail in a specified area to enclose the space shuttle's cargo bay on the pad for installation or removal of payloads. Mobile Launcher 2, center right, is on the pad to support the PCR during construction. Photo Credit: NASA