Flight hardware for the Space Shuttle is manufactured at many locations around the United States by NASA prime contractors and subcontractors.
In the case of the orbiter, the prime contractor is Rockwell International, Downey, Calif., and major components and subsystems for it are assembled at the firm's production plant at Palmdale, Calif. After an orbiter is built, it is flown to NASA's Kennedy Space Center (KSC) Fla., atop a specially-equipped Boeing-747 aircraft called the Shuttle Carrier Aircraft.
The Space Shuttle main engines are produced by the Rocketdyne Division of Rockwell International, Canoga Park, Calif. The engines are shipped to the KSC after they have undergone engine test firings on stands at NASA's John C. Stennis Space Center (formerly the National Space Technology Laboratories) near Bay St. Louis, Miss.
The Shuttle's huge external tank is built at NASA's Michoud Assembly Facility near New Orleans, La., by Martin Marietta Corp., Michoud Aerospace. The tanks are shipped to KSC by barge, arriving at the center's turn basin canal in the Launch Complex 39 area, where they are unloaded and moved to the Vehicle Assembly Building (VAB).
Several aerospace firms components for the Shuttle's solid rocket boosters (SRB). The solid propellant motors are built by the Wasatch Division of the Morton Thiokol Chemical Corp., Brigham City, Utah.
All other SRB components are produced by United Space Boosters, Inc., Huntsville, Ala. Booster stacking -- assembly of the entire solid rocket booster -- is performed by the Lockheed Space Operations Co., Titusville, Fla., the Shuttle processing contractor at KSC.
Processing flow procedures for new and reused Shuttle flight hardware are essentially similar. Differences in the procedures occur early in the pre-integration activity. For example, newly- produced orbiters usually undergo a period of powered-down processing to allow time to finish work that may not have been completed at the manufacturing plant, or to make modifications ordered after the orbiter leaves the plant. Also, during the initial flow processing of a new orbiter, the main engines and orbiter maneuvering system pods undergo checkouts before being installed.
Another requirement for new orbiters is that their main engines are test fired on the launch pad. Called the Flight Readiness Firing, the purpose of the test is to verify that the main propulsion system works the way it is designed to work.
For orbiters that have already flown, turnaround processing procedures include various post-flight deservicing and maintenance functions which are carried out in parallel with payload removal and the installation of equipment needed for the next mission.
If new flight hardware is called for, additional pre-launch tests are usually needed. For example, if new auxiliary power units (APU) are installed, they must undergo "hot firings" to verify their operational readiness.
If changes are made in external tank design, the tank usually will usually require a tanking test in which it is loaded with liquid oxygen and hydrogen just as it is before launch. This is called a "confidence check" and determines the tank's ability to withstand the high pressures and super cold temperatures of the cyrogenics.
After separate hardware checks and servicing of major flight elements are completed -- a process called stand-alone processing -- actual Shuttle vehicle integration starts with stacking of the SRBs on a Mobile Launcher Platform in one of the high bays of the VAB. Next, the external tank is moved from its VAB location and is mated with the SRBs.
The orbiter, having completed its pre-launch processing and after horizontally-integrated payloads have been installed, is towed from the Orbiter Processing Facility (OPF) to the VAB and hoisted into position alongside the SRBs and the external tank. It then is then attached to the external tank. The mating is then complete.
The mobile launcher concept was originally developed for the Apollo program. It permits the complete checkout of the vehicle in the enclosed protection of the VAB before moving the vehicle to the launch pad. This provides greater protection of flight hardware from the elements and allows for more systematic checkout processing using computer techniques. Thus, the Shuttle spends a relatively short time on the launch pad.
When the VAB pre-launch preparations are completed, the entire system -- the assembled Space Shuttle and the Mobile Launcher Platform -- is lifted by th Crawler Transporter and rolled slowly to the launch pad. The move takes about 6 hours.
At the pad, vertically integrated payloads are loaded into the payload bay. Then, propellant servicing and needed ordnance tasks are performed. Finally, the countdown gets underway, launch readiness is confirmed and launch takes place.
Only minutes following the launch, recovery crews, on station in the Atlantic Ocean off shore from the launch site, prepare to recover the spent SRBs thus beginning the process of vehicle turnaround. While the Shuttle is carrying out its mission in orbit, back on Earth the ground crews already are preparing for the next mission. Click Here for MISSION PREPARATION AND PRELAUNCH-OPERATIONS
Information content from the NSTS Shuttle Reference Manual (1988)
Last Hypertexed Wednesday October 11 17:52:13 EDT 1995
Jim Dumoulin (firstname.lastname@example.org)
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