An orbiter is towed to the Orbiter Processing Facility within hours of its arrival, either after landing at KSC or returning aboard a ferry flight on the Shuttle Carrier Aircraft. The facility has three almost identical high bays, each of which is 197 feet (60 meters) long, 150 feet (46 meters) wide, 95 feet (29 meters) high, and encompasses a 29,000-square-foot (2,694-meter) area. A low bay connects high bays 1 and 2. It is 233 feet (71 meters) long, 97 feet (30 meters) wide and nearly 25 feet (eight meters) high. High bay 3, built last, also has an adjacent low bay. Annexes and portable buildings provide additional shop and office space.

Each high bay comes equipped with a 30-ton (27-metric-ton) bridge crane with a hook height of approximately 66 feet (20 meters). Platforms, a main access bridge and two rolling bridges with trucks provide access to various parts of the orbiter. The trucks have a telescoping arm with rotatable buckets to hold workers. The high bays have an emergency exhaust system in case of a hypergolic fuel spill. The low bay contains areas for electronic, mechanical and electrical equipment, a communications room, offices and supervisory control rooms. All bays have fire protection systems.

In addition to routine postflight servicing and checkout, many of the vehicle modifications needed for future flight requirements, or to enhance vehicle performance and correct deficiencies, are performed in the Orbiter Processing Facility.

Spacecraft or payloads processed through checkout in a horizontal position, usually the larger ones such as Spacelab, are installed in the orbiter in this facility. Spacecraft handled in a vertical position normally are installed at the launch pad.

After processing, the orbiter is usually towed into the Vehicle Assembly Building transfer aisle.