Case Study 1 The Challenger Space Shuttle disaster and the ...

1 Case Study 1 TheChallenger Space ShuttledisasterandtheSolid-Fuel Rocket Booster(SRB)projectOverviewOn 28 January,1986 the Challenger Space Shuttle blew up73 seconds lives and three billion dollars worth of equipment was Challenger accident was the result of a faulty sealing system whichallowed exhaust flamesfrom the Solid-FuelRocket Boosters (SRB)to ventdirectly on the external tank, rupturing the tank and causing the identified the failure due to the improper sealing of the O- rings, thegiant black rubber loops that help seal the segments of theSRBs. The O-ringis made of a fluoroelastomer, which seals the joint between two solid rocketbooster sections. An elastomer is a material that can be deformeddramatically and recover its shape completely.

2 A rubber band is an exampleof an almost half of the Shuttle flights there was O- ring erosion in the boosterfield joints. The launch took place in untested temperature conditions and inspite of serious warnings on the part ofthe engineers ofThiokol, thecompany that manufactured the sequence of events that led tothe unfortunate events is examined in order to draw the was very anxious to proceed with the launch for a variety of reasonsincluding, economic considerations and political pressure. To justify itsbudget NASA had scheduled a large number of missions in 1986. It wasvital for the Challenger to be launchedso that there would be enough time torefurbish the launch pad to prepare it for the next launch. The EuropeanSpace Agency was providing added competition and there was politicalpressure for the Challenger to be in Space when the president of the US gavethe State of the Union were plenty of advanced warnings regarding the SRBs, from previousmissions.

3 Concerns had been voiced by Thiokol, the SRB manufacturingcompany, as to whether the fatal launch should have taken place. The coldweather, some of the coldest in Florida history, provided uncharted watersfor the operation of the went wrong? Why did NASA launch in spite of the evidence andwarnings from Thiokol engineers? Should the launch have been cancelled?Challengerspace Shuttle : Aproject success or a programfailure?At first sight, the Challenger incident can only be regarded as a failure. Lossof life and loss of equipment worth billions of dollars can only be associatedwith bad news. The television pictures of the Challenger s explosion madetheir way round the world and were broadcast over and over as the leadingnews story and will indelibly remain in people s minds for many years arriving at a verdict about the Challenger explosion, it is necessary toexamine the various events that led to NASA s twenty-fifth Shuttle mission,which proved to be fatal for the Challenger .

4 Is it possible that the SRBproject was a success, while the overall program was a failure?Background informationTo betterunderstand the conditions that existed at the time of the launchsome background information is presented belowthat includes: Technical informationrelating to the SRB project. Description of the programenvironment. Management restrictions associated tofunding issues. Invisible political reusable Space shuttleIn the post-Apolloera of thelunar landing the idea of a reusable spaceshuttle was was tomake access to Space a routine matter,similar to flying an Space Shuttle had to be reusable andeconomical to develop and operate. Thedesign of thespace Shuttle wasshaped by engineering considerations but also by pressure from the WhiteHouse and Congress to reduce the are three main components of aspace external fuel solid-fuelrocket orbiter is the vehicle which transports the astronauts into Space .

5 Theorbiter is propelled by thrusters at the back of the orbiter and the purpose ofthe external fuel tank is to pump a combination of hydrogen and oxygen fuelto the orbiter s thrusters. TheSRBs provide the majority of the thrust inorder to place the orbiter in orbit. When the orbiter is close to orbit, theSRBs detach and the orbiter is propelled only by the thruster. TheSRBsfallto earth, where they are collected to be reused in future missions. When theorbiter is in orbit the external fuel tank is also detached. The external fueltank is not at the center of theChallenger disaster and its history needs tobe SRB is ascaled up version of a Titan missile which hadbeen used successfully for general, solid- fuelrockets producemuch more thrust than liquid-fuel of their drawbacksis thatonce the solid-fuel rocket hasbeen ignited they cannot be turned off or evencontrolled.

6 It is therefore extremely important thatthe SRBs are properlydesigned, because if something goes wrong there is no second of the two SRBs was149ft ( ) long and 12ft ( ) in ignition each booster rocket weighs 2 million pounds ( millionkilograms.) The Shuttle s two solid-fuel booster rockets provide the mainpower to lift the orbiter and its external liquid-fuel tankto a height of around28 miles (45 km.)The life of each booster is around two minutes. When the SRBs are nearlyempty of fuel they disengage from the Space Shuttle and will eventually fallinto the Atlantic Ocean where they will be collected for use ina chronological history of the SRB used in the Challenger Space Shuttle isindicated below: 1974:The contract for building theSRBswas awarded to Thiokol.

7 1976:NASA accepted the SRB design. 1977: Joint rotation problems were discovered. 1981: O-ring erosion detected after the second Shuttle flight. 1985: The worst problem relating to the O-rings was exhibited afterthe January 24, 1985 Shuttle flight. 1985: On August 19, 1985, four months prior to the Challengerdisaster, the NASA management was briefed on the boosterproblems. 1986:On January 27, 1986, a few hours prior to the launch, ateleconference took place between NASA and Thiokol to discuss theeffects of cold temperature on the SRB leading to the launchThe decision by NASA to launch the Challenger Space Shuttle on 28 January, 1986 was controversial at were plenty of warning signsduring the launches that preceded the November 1981, after theshuttle s second mission, the O-rings seemed to havebeeneroded by hotgasses.

8 The January 24, 1985 launch took place in similar cold-weatherconditions as the fatal launch of January 28, 1986. After the mission thebooster joints were examined by engineers at Thiokol who found traces ofsootand grease caused by passage of hot combustion gases past the O- ringbefore it has completely sealed the joint. As a result Thiokol startedstudying the resiliency of O-rings at low temperatures. In July 1985 Thiokolordered steel billets which would be used for a redesigned case field steel billets were not ready at the time of the Challenger events a few days prior to the fatal launch are worth looking was first scheduled to be launched on22 January at 15:43. Thiswas rescheduled for 23 January and thenagain rescheduledfor 24 launch was reset for 25 January because of bad weather at abort landingsite in Dakar, Senegal.

9 Launch was rescheduled for 27 January at 09:37 dueto theprediction of unacceptable weather at Kennedy Space Center. Launchwas delayed for 24 hours when ground servicing equipment hatch closingfixture could not be removed from orbiter a conference call the night of the 27 January, 1986, engineers at Thiokolrecommended against launching below 53oF, which was thecoldesttemperature at which a previous flight had launched. On the night before thelaunch, the temperature wasexpected to be as low as 18oF, more than 30degrees colder than any other launch. Thiokol engineering was overruled byits management and the go-ahead was given to proceed with the by second account ofthe ChallengerlaunchAt 11:38 EST on January 28, 1986, the Challenger took off from the launchpad at Kennedy Space Center in Florida.

10 The key events until its explosionare indicated below: sec after ignition: Black smoke coming from bottom field jointof the right SRB, indicating that the rubber O-rings were beingburned. : Last puff of smoke seen. sec: Three bright flashes shot across the Challenger s of the flashes lasted 1/13 of a second and were unrelated to theevents leading to the explosion. sec: With enhanced film a flame was seen coming from theright SRB. sec: Without enhanced filmthe flame could be seen increasingin size and beginning to push against the external tank. sec: The first sight that the flame was hitting the external is also a change in the color of the flame indicating that theflame was being produced by the mixing with another substance. Inthis case the other substance was liquid Hydrogen stored in theexternal tank.