Implications and Ramifications of Engineering Design of Field Joint for Space Shuttle: STS 51-L1 Akila Sankar, Emory University Chetan S. Sankar, Auburn University P.K. Raju, Auburn University Vamsee Dasaka, Auburn University since NASA worked very hard to com- plete nine missions in 1985. William P. Rogers, Chairman of the Rogers Commis- sion, explained: …the attempt to build up to 24 mis- sions a year brought a number of dif- ficulties, among them the compres- sion of training schedules, the lack of spare parts, and the focusing of resources on near-term problems…. Introduction The part of the system responsible for The Launch of turning the mission requirements and Joe Kilminster, the Vice-President of the Space Shuttle Space Booster Programs at Morton objectives into flight software, flight Thiokol, Inc. (MTI), flipped the telecon- On April 12, 1981, trajectory information and crew ference switch in the MTI conference the world watched the training materials was struggling to room on January 27th, 1986. MTI had Orbiter Columbia climb keep up with the flight rate in late successfully created the Solid Rocket into space (Figure 1) 2 . 1985…It was falling behind because Booster, the first solid fuel propellant sys- After nine years of de- its resources were strained to the 3 tem, for the NASA Space Shuttle and it signing the first space limit… had worked without fail in all 24 Shuttle shuttle, engineers and The “routine” sentiment toward the launches. Although MTI and NASA had Figure 1 managers throughout Shuttle operations not only strained re- encountered problems with the Solid the United States cel- sources, but also created a sense of secu- Rocket Booster field joint during 1972 ebrated its first flight. NASA had been rity among the Shuttle team. William to 1980, design modifications of larger working with several contractors since Rogers explained this trend: O-rings and thicker shims had been in- 1972 to produce the Space Shuttle as a Following successful completion of stituted to help fix the problem. There means of reusable and cost-effective the orbital flight test phase of the had been questions created by a MTI task transportation into space. The roar of Shuttle program, the Shuttle was de- force and Marshall Space Center manage- Columbia’s solid rocket boosters signi- clared to be operational. Subse- ment about the reliability of the O-rings. fied a success for the Space Shuttle team. quently, several safety, reliability, However, during the teleconference on The ascent of Columbia in 1981 and quality assurance organizations January 27th, Mr. Kilminster was sur- marked the first of four test flights of the found themselves with reduced and/ prised to learn the seriousness of the situ- space shuttle system. These test flights or reorganized functional capabil- ation when MTI engineers wanted to re- were conducted between April 1981 and ity… The apparent reason for such verse the decision of the NASA Flight July 1982 with over 1,000 tests and data actions was a perception that less Readiness Review and persuade MTI and collection procedures. The landing of safety, reliability, and quality assur- NASA management that Flight 51-L STS-4 (Space Transportation System – 4) ance activity would be required dur- should not be launched the next day. MTI in July 1982 concluded the orbital test ing “routine” Shuttle operations.4 engineers were convinced that the pos- flight program with 95% of the objectives sible effect of freezing temperatures on accomplished. In other words, the NASA focus had the SRB field joint could cause major At this point, NASA declared the shifted from developing effective space problems within the Space Shuttle sys- Space Shuttle “operational” and a heavy transportation to using space transporta- tems. As the teleconference proceeded launch schedule was planned for the fu- tion effectively. and the engineers and managers debated ture. An early plan called for an eventual This new NASA focus propelled the the issues, it became clear to Mr. rate of a space mission per week but real- achievement of many Shuttle feats in its Kilminster that a difficult decision must ism forced revisions. In 1985, NASA twenty-four missions between 1982 and be made. MTI would have to decide published a projection calling for an an- 1986. The Orbiter Columbia made seven whether or not to recommend that NASA nual rate of 24 flights by 1990. How- trips into space, the Discovery six, the launch the STS 51-L, the Challenger. ever, this seemed to be an ambitious goal Atlantis two, and the Challenger nine. In 1/1 January-April 2000 37 1 these 24 missions the Shuttle demon- countdown, all engines are ignited and the that is 154 feet long and 27 2 feet in di- 1 strated its ability to deliver a wide vari- shuttle lifts off from the launch pad. The ameter. About 8 2 minutes after lift-off ety of payloads, to serve as an orbital Solid Rocket Boosters (SRBs) power the the Orbiter jettisons the External Tank. laboratory, to serve as a platform to erect Orbiter and the External Fuel Tank dur- The External Tank breaks up upon atmo- large structures, and to help retrieve and ing the first two minutes of flight. The spheric entry and is the only Space Shuttle repair orbiting satellites. Appendix 1 SRBs are the largest solid-propellant component that is not reused. chronologically summarizes the events in motors ever flown and the first ever de- The flight in space begins when the this case study. Appendix 2 provides a signed to be reused (Appendix 3). They Orbiter jettisons the external tank. Once Marshall and MTI organizational chart. contribute about 80% of total thrust at lift- the Orbiter is in space, it uses its main These accomplishments effectively met off and each SRB has an approximate engines for maneuverability. The Orbiter NASA’s goals for the Space Shuttle. thrust of 3,300,000 lbs. at launch. The is an aircraft-like structure with three Orbiter main engines provide the other parts: the forward fuselage with the pres- The Space Shuttle 20% of the thrust. Approximately two surized crew compartment, the mid-fuse- minutes after lift-off, the SRBs exhaust lage with the payload bay, and the aft fu- The 1970s marked the development their fuel and are jettisoned from the Or- selage with the main engine nozzles and of the Space Shuttle (Figure 2). The biter and External Tank. The SRBs fall the vertical tail. It can carry up to 8 as- into a designated point in tronauts, launch 24 tons of cargo into the ocean, where ships space, and return to Earth with 16 tons of recover them. cargo. After the SRBs de- After the experiments and activities of tach, the Orbiter main the mission are complete, the Orbiter de- engines propel the Or- scent/landing section begins. The re-en- biter and the External try into the atmosphere is the first stage Tank to the upper reaches of the descent. The Orbiter is covered of the atmosphere. with delicate high temperature heat tiles Throughout the launch, to protect it from the intense friction the External Fuel Tank caused by the atmosphere upon re-entry. provides the propellants The Orbiter descends through the atmo- for the Orbiter’s main sphere and lands at either Edwards Air engines: 143,000 gallons Force Base in California or at Kennedy of liquid oxygen, and Space Center in Florida. This landing on 383,000 gallons of liquid the concrete runway concludes the typi- hydrogen. The External cal mission in space. Fuel Tank is made from Although the mission profile and welded aluminum alloy shuttle design was intricately planned, the Figure 2 shuttle had three major elements: two Solid Rocket Boosters, an External Fuel Tank, and the Orbiter that houses the as- tronauts. With this design, both the Solid Rocket Boosters and the Orbiter would be re-used saving large manufacturing costs and turn-around time. NASA’s de- sire to create a high frequency of flights necessitated a detailed and consistent pro- file for every shuttle mission. The profile documented the schedule of events that would take place during a shuttle mission (Figure 35 ). A shuttle mission consists of three major events: launch into orbit, flight in space, and the descent/landing on Earth. A typical launch into orbit begins with testing of the shuttle systems. Once test- ing of all systems is complete, the astro- nauts enter the pressurized crew compart- ment in the front of the Orbiter. After the Figure 3 38 Journal of SMET Education fiscal environment of the 1970s was aus- ure 4), the main propellants for the Shuttle causing an explosion of the fuel. The tere and the planned five-Orbiter fleet was during initial launch. A stack of cylin- explosion could result in the loss of the reduced to four. These budgetary issues drical segments, each SRB is 149.16 ft mission as well as the lives of the astro- were compounded by engineering prob- long and 12.17 ft in diameter, and weighs nauts. lems that contributed to schedule delays. approximately 1,300,000 lbs. at launch. The Morton-Thiokol field joint de- The initial orbital test flights were delayed The segmented design allows the sign, based upon the Air Force’s Titan III by more than two years. The first test boosters to be easily transported by rail solid-fuel rocket field joint, is illustrated craft was the Orbiter Enterprise, a full size between MTI’s complex in Utah model of the space shuttle without the and Kennedy Space Center in engines and other systems needed for or- Florida.