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The sense of exploration is intimately bound up withhuman resolve, and for a nation to believe that it is still
committed to forward motion is to ensure its continuance.
James A. Michener
NASA photo
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Quest for Perfection...
The Space Shuttle Reusable Solid Rocket Motor
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Inovation...Delivered.
The Cycle
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As the Apollo program came to a close, thedevelopment of a manned, reusable spacetransportation system became the primaryfocus of the U.S. space effort. In 1974, ATKwas chosen by the National Aeronautics and
Space Administration (NASA) to design andbuild the solid rocket motors that would boostthe eet of orbiters from the launch pad tothe edge of space. ATKs efforts were rewardedin 1981 with the maiden ight ofColumbia (STS-1). A new era in space explorationhad begun.
The Space Shuttle reusable solid rocket motor(RSRM) is the largest solid rocket motor ever
own and the rst designed for reuse. Fromignition to end of burn, each RSRM generatesan average thrust of 2,600,000 pounds and burnsfor approximately 123.6 seconds. Each motor isjust over 126 feet long and 12 feet in diameter.The entire boosterincluding nose cap,frustum, and the forward and aft skirtsisapproximately 149 feet long. Of the motorstotal weight of 1,300,000 pounds, propellantaccounts for 1,107,000 pounds. Each launch
requires the boost of two RSRMs. By the timethe twin RSRMs have completed their task,the Space Shuttle orbiter has reached analtitude of 24 nautical miles and is traveling ata speed in excess of 3,000 miles per hour.
With safety, quality, and reliability as theirprimary objectives, ATK engineers directapproximately 110,000 quality control inspectionson each RSRM ight set. In addition, RSRMs are
periodically static tested as part of an ongoingquality assurance and development process.Nothing is left to chance.
THE LAUNCH
People who have had the opportunity to witness a Space Shuttlelaunch walk away impressed, the sight and sound indelibly etched intheir minds. The RSRMs together produce an incredible 5.3 millionpounds of maximum thrust. This translates into approximately 71percent of the thrust needed to propel the orbiter and its crew to aspeed of 3,094 miles per hour and an altitude of 24 nautical miles. It ia high-tech event that can be matched by no other nation.
RECOVERYOnce their task is complete, the RSRMs separate from the orbiter and fatheir descent slowed by parachute to the ocean below. They come to reapproximately 141 miles downrange, oating in a nozzle-end-down posiThey are recovered and returned to the mainland, where they will berefurbished and prepared for their next Space Shuttle mission.
REFURBISHMENT
From Cape Canaveral, the spent RSRMs are shipped by railcar back toATKs Utah facilities. With great care, they are cleaned, inspected, and
tested to become candidates for a future launch and remain an integralpart of the cycle.
CASE PREPARATION
The RSRM case is made up of nine cylinders, an aft dome, and a forwadome. In preparation for their solid propellant, the cylinders are joined ifour primary segments. These are called casting segments. Insulationcapable of protecting the case from the high temperatures of motoroperation is applied. The propellant will be bonded to this case-protectinsulation.
PROPELLANT CASTING
The solid propellant that powers the RSRMs is liquid when poured into
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four primary segments that comprise each motor. The propellant is curover a period of four days. During this curing process, the propellantsolidies. It requires approximately 40 seven-thousand-pound batcheof propellant to ll each segment. A fully loaded RSRM contains ovea million pounds of solid propellant.
NOZZLE MANUFACTURE
The nozzle is a complex structure consisting of layers of glass andcarbon-cloth materials bonded to aluminum and steel structures.
These materials are wound at specied angles, then cured to form adense, homogeneous insulating material capable of withstandingtemperatures reaching 6,000o F. The cured components are thenadhesively bonded to their metal support structures. Finally, the metasections are joined to form the complete nozzle assembly.
FINAL ASSEMBLY
Before an RSRM is certied for launch, it is X-rayed and ultrasonicainspected to ensure that no aws or inconsistencies exist in thepropellant or insulation. The nozzle is then installed in the aft segmen
and the igniter installed in the forward. Once the systems tunnel is inplace, the segment is prepared for shipping
STACKING
Upon reaching their Florida destination, the segments are removedfrom their railcars, inspected, and, ultimately, transported to theVehicle Assembly Building. There, they are stacked and prepared formating with the external tank and the orbiter.
THE LAUNCH
At this point, the next launch is not far off. The mobile launch platforwill soon carry another Space Shuttle stack to the launch site. And atignition, the cycle will begin anew.
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The RSRM
September 2008
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Media Contact: George Torresphone: 801-699-2637e-mail: [email protected]
THE IGNITERThe igniter is itself an internally mounted solid rocket motor. It is approximately 48inches long and 17 inches in diameter. Containing 134 pounds of propellant, theigniter, when electrically activated, spreads ame down the entire length of thesolid rocket motor. Approximately 0.34 seconds later, the Space Shuttle orbiterbegins its ascent.
THE MOTOR CASEConsisting of 11 steel sectionsnine cylinders, an aft dome, and a forwarddomejoined tang to clevis and held together by load-bearing pins, the case isweld-free. Moreover, its segments are reusable, designed to perform safely andpredictably for up to 20 launches.
THE PROPELLANTWhen we speak of solid rocket motors, we are referring to the propellant, whichis solid and has somewhat the same consistency as the eraser on a pencil. Thesolid propellant used to power the Space Shuttle is a composition of aluminumpowder (the fuel), ammonium perchlorate (the oxidizer), HB polymer (the binder), ameasured amount of iron oxide to ensure the desired propellant burn rate, and anepoxy curing agent.
THE NOZZLEThe RSRM nozzle, the point of exit for the hot gases of combustion, is designed tomove up to eight degrees in any direction. This is made possible by the exiblebearing. This capability to direct the motors thrust is crucial to guiding the orbiteralong its proper trajectory until the RSRMsseparate approximately two minutes after liftoff.
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