NASA's John F. Kennedy Space Center.in Florida is responsible for all launch, landing and turnaround operations for STS missions requiring equatorial orbits.
The Lyndon B. Johnson Space Center in Houston, Texas, is responsible for the integration of the complete space shuttle vehicle and is the central control point for space shuttle missions.
NASA's George C. Marshall Space Flight Center in Huntsville, Ala., is responsible for the space shuttle main engines, external tanks and solid rocket boosters.
NASA's National Space Technology Laboratories at Bay St. Louis, Miss., is responsible for testing the space shuttle main engines.
NASA's Goddard Space Flight Center in Greenbelt, Md., operates a worldwide tracking station network.
The United States Air Force operates the space shuttle launch and landing facility at Vandenberg Air Force Base in California for STS missions requiring polar orbit.
JOHN F. Kennedy Space Center.p> The Kennedy Space Center.has primary responsibility for prelaunch checkout, launch, ground turnaround operations and support operations for the space shuttle and its payloads. Space shuttle payloads are processed in a number of facilities at KSC and the nearby Cape Canaveral Air Force Station. Payloads are installed in the space shuttle orbiter horizontally in the Orbiter Processing Facility or vertically at the launch pad. Payloads to be installed horizontally in the orbiter at the Orbiter Processing Facility are verified in the Operations and Checkout Building at KSC. Payloads installed vertically in the orbiter at the launch pad consist primarily of automated spacecraft involving upper stages and their payloads (e.g., satellites).
KSC's responsibility extends to ground operations management systems and plans, processing schedules, facility design and logistics in support of the space shuttle system and payloads.
The center established the requirements for facilities and ground operations support at Vandenberg Air Force Base and designated contingency landing sites. KSC also supports the Department of Defense for ground operations at Vandenberg Air Force Base and maintains NASA facilities and ground support equipment there.
The launch facilities-Launch Complexes 39-A and 39-B-and the technical support base of the center's industrial area were carved out of virgin savanna and marsh in the early 1960s for the Apollo program.
In reshaping KSC for the space shuttle, planners took maximum advantage of existing buildings and structures from the Apollo program that could be modified, scheduling new ones only when a unique requirement existed. New facilities that have been built to support space shuttle operations are the shuttle landing facility (runway); the Orbiter Processing Facility; and recently the Orbiter Modification and Refurbishment Facility, Tile Processing Facility, Solid Rocket Booster Storage and Processing Facility, Shuttle Logistics Building and Solid Rocket Booster Assembly and Refurbishment Facility.
KSC is located at 28.5 degrees north latitude and 80.5 degrees west longitude. It encompasses approximately 140,000 acres of land and water. This area, with the adjoining bodies of water, is sufficient to afford adequate safety to the surrounding communities during space shuttle launch and landing activities.
The shuttle processing contractor performs all launch processing and turnaround activities at the Kennedy Space Center.and Vandenberg Air Force Base. Lockheed Space Operations Company, Titusville, Fla., was awarded the contract in 1983 to perform space shuttle launch processing operations previously carried out by more than a dozen separate contractors, which included the major hardware manufacturers.
The SPC is responsible for processing individual vehicle elements, integrating those elements in preparation for launch, performing cargo integration and validation activities with the orbiter, operating and maintaining assigned facilities and required support equipment and performing those tasks necessary to accomplish launch and postlaunch activities successfully.
The OPF has two identical bays that are each 197 feet long, 150 feet wide and 95 feet high; have an area of 29,000 square feet; and are equipped with two 30-ton bridge cranes with a hook height of approximately 66 feet. A low bay separating the two bays is 233 feet long, 97 feet wide and 24.6 feet high. A 10,000-square- foot annex is located on the north side of the facility. Another new 34,000-square- foot, three-story annex will provide additional office space.
In the high bays, a trench system under the floor contains electrical, electronic, communication, instrumentation and control cabling; hydraulic supply and return plumbing; gaseous nitrogen, oxygen and helium plumbing; and compressed air distribution plumbing. Gaseous nitrogen, helium and compressed air are supplied by the systems in the Vehicle Assembly Building. All of these systems are used to support processing and maintenance of the orbiters during ground turnaround operations.
The two high bays have an emergency exhaust system in case of hypergolic spills. The low bay houses areas for electronic equipment, a launch processing system interface, mechanical and electrical equipment shops and thermal protection system repair. The low bay also includes provisions for a communications room, offices and supervisory control rooms.
Some orbiter processing activities performed in the OPF are hazardous, and personnel who are directly involved are required to wear protective suits, called self-contained atmosphere protective ensembles. The use of SCAPE suits is required during operations involving the reaction control system, orbital maneuvering system, and auxiliary power units and their hypergolic propellants.
Fire protection systems are provided in all three bays.
Two large rolling bridges span the main access bridge to provide complete access to installed payloads, radiators, internal areas of the payload bay and external areas of the payload bay doors. Each of the rolling bridges supports two independently movable trucks with a personnel bucket at the bottom of each vertically telescoping arm. The buckets are manually rotatable around a full circle. The bridges, trucks and telescoping arms are electrically powered and controlled from the buckets or the catwalk.
Flip-up work platforms parallel the payload bay area to provide access to radiators, the inside payload bay doors, payload bay door hinges and trunnion points.
Other platforms provide access to other orbiter elements.
The hinges of the payload bay doors are not designed to support the weight of the doors while they are open horizontally in the Earth's 1-g environment. A counterweight zero-gravity device supports the weight of the doors while they are open for processing in the OPF.
The orbiter processing flow begins when an orbiter lands at the shuttle landing facility after a mission in space or a ferry flight aboard the shuttle carrier aircraft. In either case, the orbiter is towed to the OPF within hours of its arrival.
Processing starts when the orbiter is jacked up off its landing gear and leveled, workstands are moved into position and preparations begin to gain access to various orbiter areas. The orbiter is connected to ground power, facility ground coolant, purge air and the LPS.
Initial safing operations include hooking up purge, vent and drain lines. Any unexpended pyrotechnics (ordnance devices), such as those used for backup landing gear deployment, are disabled and safed. Purging and deservicing of the orbiter's orbital maneuvering system/reaction control system, forward reaction control system and auxiliary power unit hypergolic systems are initiated.
Some of these are hazardous operations, which require that the OPF be cleared of all non-essential personnel. Hypergolic deservicing operations require that personnel wear SCAPE suits.
The hypergolic lines of the OMS/RCS and forward RCS are drained of trapped propellants and their interface connections are purged. Residual hypergolic fuels in onboard tanks are not usually drained.
After the orbiter has been rolled into the OPF, a purge of the space shuttle main engines is initiated to remove moisture produced as a by-product of the combustion of liquid oxygen and liquid hydrogen.
Fuel cell cryogenic tanks are drained of residual reactants and rendered inert using gaseous nitrogen in the oxygen system and gaseous helium in the hydrogen system. High-pressure gases are vented from the environmental control and life support system.
Before postflight deservicing can continue beyond initial safing operations, certain vehicle systems must be mechanically secured and personnel access installed.
Space shuttle main engine gimbal locks and engine covers are installed, and engine heat shields are removed. Aft access doors are removed, and workstands are installed in the orbiter's rear compartment.
Payloads and the associated airborne support equipment from the previous flight are removed from the orbiter payload bay, and the bay is prepared for the installation of new payloads. The remote manipulator system arm is removed or installed, as required for the next mission.
During routine deservicing operations, non-storable consumables are off-loaded from the orbiter and waste products are removed. Potable water, water from the water spray boilers and lube oil from the auxiliary power units are drained, and APU lube oil filters are removed.
After initial safing is completed, postflight troubleshooting of anomalies that occurred during launch, flight or re-entry begins.
Orbiter components are removed and repaired or replaced as required based on anomaly reviews and then retested in parallel with other processing activities.
Visual inspections are made of the orbiter's thermal protection system, selected structural elements, landing gear, tires and other systems to determine if they sustained any damage during flight and landing.
Any damage to the thermal protection system must be repaired before the next mission. TPS operations are conducted in parallel with most of the activities in the Orbiter Processing Facility. There are some 27,446 tiles and thermal blankets on the outside of each orbiter and some 6,000 thermal control blankets on the inside.
TPS maintenance is provided in the new Thermal Protection System Facility across the street from the OPF. The 33,000-square- foot facility was located near the OPF to minimize the time it takes to transport the tiles and thermal control system blankets between the two facilities. Several trips are required before the tiles and some blankets are installed on the orbiter. The closeness of the facilities is also expected to minimize damage to the delicate tiles.
During OPF processing, any vehicle modifications required in addition to routine postflight deservicing/servicing and checkout are performed. Planned modifications are typically put into work as soon as practical after the orbiter returns and are completed in parallel with prelaunch servicing whenever possible.
Modifications may be performed to meet future mission requirements, resolve an identified deficiency or enhance vehicle performance by replacing existing hardware with new, improved designs.
Orbiter modifications, if they are extensive, may be performed with the vehicle powered down. Many modifications, however, can be completed in parallel with routine servicing while the orbiter is powered up.
Where possible, modification work is completed in the OPF and Orbiter Modification and Refurbishment Facility while the orbiter is in a horizontal position. While some modification work can be carried out in the Vehicle Assembly Building or on the pad if necessary, the OPF and OMRF offer the best access and support equipment for conducting such work.
Except during hazardous operations, routine preflight servicing can begin while deservicing activities are still under way or modifications are in work. Routine servicing includes reconfig uring orbiter systems for flight, performing routine maintenance, replacing parts and installing new mission flight kits and payloads. Consumable fluids and gases are loaded aboard, and the APU lube oil system is serviced.
As systems servicing is completed, functional checks are performed to verify flight readiness prior to closeout. Any system that fails the functional check undergoes troubleshooting to identify the problem. If required, subsequent repairs or replacements are performed.
The orbiter's hydraulically activated flight control surfaces are thoroughly checked out.
A new payload may be installed in the OPF before shuttle vehicle integration or at the launch pad after shuttle integration. Depending on the particular mission, new payloads could be installed at both locations. If payloads are installed in the OPF, the orbiter-to-payload interfaces are verified before the orbiter is moved to the VAB.
Following all space shuttle main engine work, the orbiter's main propulsion system, including the three main engines, undergoes a helium signature leak check. Successful completion of this test generally clears the way for the closeout of the aft engine compartment.
Electrically initiated pyrotechnic devices (ordnance) required for orbiter systems are installed and checked out. These include small explosive charges like those used for the backup deployment of the orbiter landing gear or emergency jettison of the remote manipulator system, Ku-band antenna, side hatch jettison and secondary emergency egress jettison.
Upon completion of all payload installation activities or any other work being performed in the payload bay, the clamshell-shaped payload bay doors are closed and latched. If no payloads are to be installed at the pad, this represents final closeout of the orbiter midbody for flight.
The final tasks to be completed in the OPF before the orbiter is moved to the Vehicle Assembly Building are to weigh the orbiter and determine its center of gravity. Vehicle performance is affected by both weight and center of gravity, and flight programming requires an accurate determination of both parameters.
The OMRF high bay is 197 feet long, 150 feet wide and 95 feet high, the same as the two OPF bays. The facility's electrical, mechanical and communications control rooms are located in an adjacent support bay. There is office space for personnel and a conference room with a window that overlooks the processing bay.
Only non-hazardous work will be performed in the OMRF until it is properly outfitted like the OPF to handle hazardous operations. In the meantime, work on the orbiter includes most thermal protection system operations, thermal protection system rewaterproofing, modifications that the facility can support and general maintenance.
Future upgrades to the facility will allow safing and deservicing; limited orbiter power-up using mobile electrical ground power; servicing of the orbiter's power reactant storage and distribution system; dumping of the orbiter's flight recorders, which requires support of the Launch Control Center computers; servicing of the orbiter's Freon coolant loop systems; and other tests requiring support of the Launch Control Center.
One of the largest buildings in the world, the VAB covers 8 acres and has a volume of 129,428,000 cubic feet. It is 525 feet tall, 715 feet long and 518 feet wide. The building is divided into a 525-foot-tall high bay and a 210-foot-tall low bay. A transfer aisle running north and south connects and transects the two bays, permitting easy movement of vehicle elements.
The high bay is divided into four separate bays. The two on the west side of the structure-Bays 2 and 4-are used for storing space shuttle orbiter external tanks. The two bays facing east-Bays 1 and 3-are used for the vertical assembly of space shuttle vehicles on the mobile launcher platform.
Extendable platforms, modified to fit the space shuttle configuration, move in around the vehicle to provide access for integration and final testing. When checkout is complete, the platforms move back, and the VAB doors are opened to permit the crawler-transporter to move the mobile launcher platform and assembled space shuttle vehicle to the launch pad. The high bay door is 456 feet high. It is divided into lower and upper sections. The lower door is 152 feet wide and 114 feet high with four door leaves that move horizontally. The upper door is 342 feet high and 76 feet wide with seven door leaves that move vertically.
The low bay was the initial site for refurbishment and subassembly of solid rocket booster segments. These activities now occur at a new facility north of the VAB.
Existing pneumatic, environmental control, light and water systems have been modified in both bays. The north doors to the VAB transfer aisle have also been widened 40 feet to permit the orbiter to enter when it is towed over from the Orbiter Processing Facility. The doors are slotted at the center to accommodate the orbiter's vertical stabilizer.
The Vehicle Assembly Building has more than 70 lifting devices, including two 250-ton bridge cranes.
The VAB is designed to withstand winds of up to 125 miles per hour. Its foundation rests on more than 4,200 open- end steel pilings 16 inches in diameter driven down 160 feet to bedrock.
The storage cells provide only the minimum access and equipment required to secure the external tank in position. After the tank is transferred to the checkout cell, permanent and mobile platforms are positioned to provide access to inspect the tank for possible damage during transit and to remove hoisting equipment. The liquid oxygen and liquid hydrogen tanks are then sampled and receive a blanket pressure of gaseous nitrogen and gaseous helium, respectively, in preparation for a normal checkout.
The external tank subsystem checkout includes an inspection of the external insulation and connection of ground support equipment (including the launch processing system) to the appropriate interfaces. Electrical, instrumentation and mechanical function checks and tank and line leak checks are performed in parallel.
After satisfactory checkout of the external tank subsystems, ground support equipment and launch processing system equipment are removed and stored, and external tank closeout is initiated. Forward hoisting equipment is attached and work platforms are stored-or opened-in preparation for transferring the tank to the mobile launcher platform.
The external tank is hoisted vertically from the checkout cell by the 250-ton high bay crane and transferred to the mobile launcher platform in High Bay 1 or 3 for mating with the already-assembled solid rocket boosters. After the external tank and solid rocket booster are mated, the integration cell ground support equipment is connected, and intertank work platforms are installed.
A considerable amount of final closeout work is performed on the boosters and the tank after they are mated.
Three engine workstands are available to support major stand-alone engine work, if required. The facility can support main engine disassembly and reassembly, checkout and leak testing.
Engines, mounted on engine handling devices and protected by a cylindrical shipping cover, arrive by truck from NASA's National Space Technology Laboratories and are off-loaded in the VAB transfer aisle next to the engine workshop. The engines are then pulled into the workshop and undergo receiving inspections. Normally, newly delivered engines are transferred to an engine installer and transported to the Orbiter Processing Facility for installation.
Routine postflight deservicing of the engines is performed in the OPF with the engines in place aboard the orbiter. More extensive between-flight servicing can be performed in the main engine workshop. The shop also supports engine removal operations and the preparation of engines for shipment back to NSTL or Rocketdyne in Canoga Park, Calif., the manufacturer of the SSMEs.
When they arrive at KSC, the segments are delivered to the solid rocket motor Rotation, Processing and Surge Facility, a group of steel-framed structures designed to withstand hurricane-force winds.
The RPSF, located north of the Vehicle Assembly Building, comprises a processing facility, a support building and two segment surge (storage) buildings. The facilities isolate hazardous operations associated with solid rocket motor rotation and processing (formerly performed in High Bay 4 of the VAB) and avert impacts to VAB launch-support capabilities.
The rotation building is 98.6 feet high and has an area of 18,800 square feet.
The main facility in the complex is used for solid rocket motor receiving, rotation and inspection and supports aft booster buildup. Rail tracks within the building permit railroad cars containing the segments to be positioned directly under one of the two 200-ton overhead bridge cranes. A tug vehicle capable of pulling and stopping a fully loaded segment car moves and positions railcars in the building.
Recovered booster segments are loaded onto railcars for shipment back to the manufacturer at a site on Contractor Road.
Two surge buildings located nearby contain 6,000 square feet each of floor area for storage of eight segments (one flight set). The buildings are 61 feet in height in the aft segment storage area and 43 feet in the forward and center segment storage area.
Paved roads between the processing facility, the two storage buildings and the VAB permit transporters to transfer the segments and other hardware from one facility to another.
Live solid rocket motor segments arrive at the processing facility and are positioned under one of the cranes. Handling slings are then attached to the railcar cover, and it is removed. The segment is inspected while it remains in the horizontal position.
The two overhead cranes hoist the segment, rotate it to the vertical position and place it on a fixed stand. The aft handling ring is then removed. The segment is hoisted again and lowered onto a transportation and storage pallet, and the forward handling ring is removed to allow inspections. It is then transported to one of the surge buildings and temporarily stored until it is needed for booster stacking in the VAB.
Solid rocket booster operations are performed by both the shuttle processing contractor and the booster assembly contractor, who is responsible for booster disassembly and refurbishment and the assembly and checkout of forward and aft skirt subassemblies in the VAB. Booster retrieval operations, parachute refurbishment and booster stacking activities, in addition to integrated checkout, are performed by the shuttle processing contractor.
Aft skirts, fully configured and checked out in the Solid Rocket Booster Assembly and Refurbishment Facility, are delivered to the RPSF on dollies and hoisted into position on workstands. An inspected aft segment is then hoisted into position for mating with the aft skirt. When the aft segment assembly is completed and transferred to a pallet, it is transported directly to the VAB or to one of the two storage buildings.
Solid rocket booster elements, such as forward skirts, aft skirts, frustums, nose caps, recovery systems, electronics and instrumentation components, and elements of the thrust vector control system are received in this facility.
Assembly and checkout of the forward assembly (nose cap, frustum and forward skirt) and aft skirt assembly are also performed here in addition to refurbishment of recovered booster flight hardware.
An SRB hydraulic power unit ''hot fire'' facility is located in the southeast corner of the 44-acre site. The facility features a test stand that supports the hot-firing of the solid rocket booster's hydrazine-fueled thrust vector control system. Before each flight, the solid rocket booster aft skirt assemblies containing the TVC are transported to the facility and test-fired before the aft booster buildup.
The stacking of the solid rocket booster major assemblies begins after the buildup of aft booster assemblies at the Solid Rocket Motor Processing Facility (north of the VAB) and checkout of the forward nose skirt assemblies in the Solid Rocket Booster Assembly and Refurbishment Facility.
The booster stacking operation is accomplished in the following sequence:
1. The aft booster assemblies are transferred from the buildup area in the Rotation, Processing and Surge Facility to the High Bay 1 or 3 integration cells in the VAB and attached to the mobile launcher platform support posts.
2. Continuing serially, the aft, aft center, forward center and forward rocket motor segments are stacked to form complete solid rocket motor assemblies. As each segment is mated, the joint seal is inspected visually.
3. Segment seal integrity is then demonstrated by a leak check and decay test between the redundant seals. The forward skirt/nose assemblies are transferred from the SRB ARF to the High Bay 1 or 3 integration cell and stacked atop the completed solid rocket motor assemblies to form a complete set of boosters.
An alignment check of the complete flight set of solid rocket booster assemblies is performed after the stacking operations are completed. Integrated and automated systems testing of the assembled solid rocket boosters is accomplished on the mobile launcher platform, using the launch processing system to simulate the external tank and orbiter.
Before the space shuttle vehicle is transferred to the launch pad, solid rocket booster flight batteries are installed. Final connection of the solid rocket booster pyrotechnic systems is performed at the launch pad.
The solid rocket booster's hydraulic power units are serviced with hydrazine during the prelaunch propellant-servicing operations at the launch pad.
Almost complete external access to the shuttle vehicle is provided in the Vehicle Assembly Building. Access to the payload bay is through the crew compartment since the payload bay doors cannot be opened in the Vehicle Assembly Building.
The mobile launcher platform is a two-story steel structure 25 feet high, 160 feet long and 135 feet wide. It is constructed of welded steel up to 6 inches thick. At their park site north of the Vehicle Assembly Building, in the Vehicle Assembly Building high bays and at the launch pad, the mobile launcher platforms rest on six 22-foot- tall pedestals.
Three openings are provided in the mobile launcher platform-two for solid rocket booster exhaust and one for space shuttle main engine exhaust. The solid rocket booster exhaust holes are 42 feet long and 20 feet wide. The space shuttle main engine exhaust opening is 34 feet long and 31 feet wide.
Inside the platform are two levels with rooms and compartments housing launch processing system hardware interface modules, system test sets, propellant-loading equipment and electrical equipment racks.
Unloaded, the mobile launcher platform weighs 8.23 million pounds. The total weight with an unfueled space shuttle aboard is 11 million pounds.
The space shuttle vehicle is supported and restrained on the mobile launcher platform during assembly, transit and pad checkout by the solid rocket booster support/hold-down system. Four conical hollow supports for each booster are located in each solid rocket booster exhaust well. The supports are 5 feet high and have a base diameter of 4 feet.
Posts on the aft skirts of the SRBs rest on spherical bearings atop the mobile launcher platform hold-down posts. A 28-inch-long, 3.5-inch-diameter stud passes vertically through the SRB post, spherical bearing and hold-down post casting to secure the booster to the platform. A frangible, or explosive, nut at the top of the stud and a nut at the bottom are tightened to preload the stud to a tension of up to 850,000 pounds.
When full main engine thrust is developed during the final moments of the launch countdown, ignition signals are sent to the two SRBs. Simultaneously, the explosive nuts at the tops of the studs are triggered. The preloaded studs are expelled downward into deceleration stands (''sandbuckets'') and the fractured halves of the explosive nuts are contained within spherical, 10-inch-diameter debris catchers on top of the solid rocket booster aft skirt posts. This sequence releases the solid rocket boosters and the entire space shuttle vehicle for flight.
Two tail service masts, one located on each side of the space shuttle main engine exhaust hole, support the fluid, gas and electrical requirements of the orbiter's liquid oxygen and liquid hydrogen aft T-0 umbilicals. The TSM assembly also protects the ground half of those umbilicals from the harsh launch environment. At launch, the solid rocket booster ignition command fires an explosive link, allowing a 20,000-pound counterweight to fall, pulling the ground half of the umbilicals away from the space shuttle vehicle and causing the mast to rotate into a blastproof structure. As it rotates backward, the mast triggers a compressed-gas thruster, causing a protective hood to move into place and completely seal the structure from the main engine exhaust.
Each TSM assembly rises 31 feet above the mobile launcher's deck, is 15 feet long with umbilical retracted, and is 9 feet wide. The umbilical carrier plates retracted at launch are 6 feet high, 4 feet wide and 8 inches thick, or about the size of a thick door.
The liquid oxygen umbilical runs through the TSM on the east side of the mobile launcher, and the liquid hydrogen umbilical runs through the TSM on the west.
Gaseous hydrogen, oxygen, helium and nitrogen; ground and flight system coolants; ground electrical power; and ground-to-vehicle data and communications also flow through the TSM umbilical links.
Work platforms used in conjunction with the mobile launcher platform provide access to the space shuttle main engine nozzles and the solid rocket boosters after they are erected in the Vehicle Assembly Building or while the space shuttle is undergoing checkout at the pad.
The main engine service platform is positioned beneath the mobile launcher platform and raised by a winch mechanism through the exhaust hole to a position directly beneath the three engines. An elevator platform with a cutout may then be extended upward around the engine bells. The orbiter engine service platform is 34 feet long and 31 feet wide. Its retracted height is 12 feet, and the extended height is 18 feet. It weighs 60,000 pounds.
Two solid rocket booster service platforms provide access to the nozzles after the vehicle has been erected on the mobile launcher platform. The platforms are raised from storage beneath the mobile launcher into the solid rocket booster exhaust holes and hung from brackets by a turnbuckle arrangement. The solid rocket booster platforms are 4 feet high, 20 feet long and 20 feet wide. Each weighs 10,000 pounds.
The orbiter and solid rocket booster service platforms are moved down the pad ramp to a position outside the exhaust area before launch.
The transporters have a leveling system designed to keep the top of the space shuttle vehicle vertical within plus or minus 10 minutes of arc-about the dimensions of a basketball. This system also provides the leveling operations required to negotiate the 5-percent ramp leading to the launch pads and to keep the load level when it is raised and lowered on pedestals at the pad and in the Vehicle Assembly Building.
The overall height of the transporter is 20 feet, from ground level to the top deck, on which the mobile launcher platform is mated for transportation. The deck is flat and about the size of a baseball diamond (90 feet square).
Each transporter is powered by two 2,750-horsepower diesel engines. The engines drive four 1,000-kilowatt generators that provide electrical power to 16 traction motors. Through gears, the traction motors turn the four double-tracked crawlers spaced 90 feet apart at each corner of the transporter.
North of the Orbiter Processing Facility is a weather-protected crawler-transporter maintenance facility in which components of the crawler-transporters can be repaired or modified. It includes a high bay with an overhead crane for lifting heavy components and a low bay for shops, parts storage and offices. A pit has been built outside on the crawlerway to accommodate track segment removal and installation.
The crawler-transporters move on a roadway 130 feet wide, almost as broad as an eight-lane turnpike. The crawlerway from the VAB to the launch pads consists of two 40-foot-wide lanes separated by a 50-foot-wide median strip. The distance from the Vehicle Assembly Building to Launch Complex 39-A is 3.4 miles and 4.2 miles to Launch Complex 39-B. The roadway is built in three layers with an average depth of 7 feet. The top surface is river gravel. The gravel is 8 inches thick on curves and 4 inches on straightaway sections.
When the space shuttle vehicle is fully assembled and checked out in the VAB, the crawler-transporter is driven into position beneath the mobile launcher platform. The transporter jacks the mobile launcher off its pedestals, and the rollout to the launch pad begins. It takes approximately five hours for the unusual transport vehicle to make the trip from the VAB to the launch pad. During the transfer, engineers and technicians aboard th crawler, assisted by ground crews, operate and monitor systems while drivers steer the vehicle towards its destination.