On January 28, 1986, at 11:38 a.m., EST, the area shuttle Challenger lifted off at Kennedy House Middle, Florida. Nevertheless, it broke aside 73 seconds into its flight, resulting in the deaths of its seven crew members. Solely 5 of the crew members have been NASA astronauts, whereas the opposite two have been civilians appearing as payload specialists. The astronauts have been the commander Francis R. Scobee, pilot Michael J. Smith, and mission specialists Judith A. Resnik, Ronald E. McNair, and Ellison S. Onizuka. The 2 civilians have been Gregory B. Jarvis and Sharon Christa McAuliffe.

Many individuals considered the launch reside due to crew member Christa McAuliffe, the primary member of the Trainer in House Challenge and the (deliberate) first feminine instructor in area. After the Challenger catastrophe, the united statesgovernment established an investigatory workforce referred to as Rogers Fee to look at the causes of the catastrophe. The catastrophe was due partly to defective booster designs and partly as a result of communication and administration failures. The Challenger catastrophe is to at the present time used as a case examine in engineering security and office ethics.

Timeline[edit]

August 1972 – NASA contractor Morton Thiokol is awarded the contract to construct shuttle strong rocket boosters at $710 million [1].

1976 – NASA accepts Morton Thiokol’s booster design. The booster rocket are to be developed at NASA’s Marshall House Flight Middle, a rocketry and spacecraft propulsion analysis heart.

1977 – Morton Thiokol discovers a joint deflection downside.

October 23, 1981 – Challenger Structural Take a look at Article (STA-099) reconstruction finalized as Challenger Orbital Car (OV-099)

November 1981 – Morton Thiokol discovers O-ring erosion after a second shuttle flight (STS-2).

April 4, 1983 – On the maiden voyage of the area shuttle, Challenger deploys a NASA communications satellite tv for pc (STS-6).

January 24, 1985 – House Shuttle Discovery’s (OV-103) Stable Rocket Boosters (related design to Challenger’s) suffered main O-ring penetration and heavy charring on the secondary O-ring (STS-51-C discovered throughout Rogers Fee investigation).

January 1985 – Roger Boisjoly, a Thiokol engineer within the Stable Rocket Booster undertaking, turns into involved about O-ring erosion after he realizes the sphere joint nearly fully failed throughout a shuttle flight (STS-51-C) [2].

April 29, 1985 – Challenger’s seventh launch (STS-51-B) suffered related O-ring points as STS-51-C (discovered by Rogers Fee).

July 31, 1985 – Roger Boisjoly sends memo and advice to delay launch to Robert Lund.

July 1985 – Thiokol orders new metal billets for brand new area joint design.

August 19, 1985 – NASA Stage I administration is knowledgeable of the booster downside.

January 27, 1986 – In a nighttime teleconference, Thiokol managers and NASA personnel talk about results of chilly temperature on O-rings. Freezing temperatures are forecasted for the subsequent morning. George Hardy, Deputy Director of the Marshall House Flight Middle, and Lawrence Mulloy, the Shuttle Program Supervisor, don’t imagine the issue to be a unprecedented danger and due to this fact resolve to not delay the launch.

January 28, 1986 – The Challenger explodes (STS-51-L).

June 9, 1986 – The Rogers Fee, an investigatory Presidential Fee, releases its report explaining the Challenger’s mode of failure. The report urges NASA to enhance shuttle security options and make organizational modifications to mission procedures.

Technical Issues[edit]

Subject joint image from Rogers Fee-Quantity 1, p.57

Stable Rocket Boosters[edit]

Glass Transition Temperature

In 1974, Morton Thiokol was chosen to obtain a NASA contract at $710 million [1] to design and construct the strong rocket boosters (SRBs). The 2 strong rocket boosters hooked up to an area shuttle orbiter offered 80% of the thrust essential to propel the shuttle into area. [3] About 2 minutes after a traditional launch, the strong rocket boosters detach and parachute again to the bottom to be reused in subsequent missions.[4] Prices have been the first concern of NASA’s choice board, and Thiokol’s low price benefits overrode different technical objections, leading to a price plus award price of roughly $800 million .[5].

The Challenger SRB issues started with the design of the joint of the casing known as the “area joint”. The unique design of the sphere joint was primarily based on the Saturn rockets’ and applied a tang and clevice, 177 pins, a face sealing O-ring, and a bore sealing O-ring. Every motor case was fabricated from 11 particular person weld-free excessive energy metal segments roughly 0.5 inches thick.[6] Static thrust testing constraints at Morton Thiokol required that the boosters be assembled horizontally which had by no means been accomplished with giant boosters. Morton Thiokol Engineer Howard McIntosh commented,“We have been involved very a lot in regards to the horizontal meeting that we needed to do to do the static checks. The Titan had at all times been assembled vertically, and so there had by no means been a bigger rocket motor to our information that was assembled (horizontally)”. So as to accomplish this the booster joints have been redesigned. The brand new design changed a face seal with a further bore seal and added zinc putty to stop the O-rings from thermal degradation.

In 1977 a hydroburst check was performed to check the energy of the rocket casings. So as to simulate the stress from combustion gases the casings have been crammed with water after which pressurized to roughly 1500 PSI.[7] This check revealed that the joint tang and clevis bent away from one another somewhat than towards one another. This resulted in a lack of O-ring stress throughout ignition and resulted in a poor seal, this phenomena was known as “joint rotation”. [5] Morton Thiokol structural supervisor Arnold Thompson commented,”We found that the joint was opening somewhat than closing as our unique evaluation had indicated, and in reality it was fairly a bit. I feel it was as much as 52 thousandths of an inch.” Engineers on the Marshall House Flight Middle and wrote to the undertaking supervisor, nevertheless, the supervisor and Deputy Director, George Hardy, didn’t ahead these memos to Thiokol’s senior decision-making board, and the sphere joint design was confirmed.[5] By 1985, Marshall and Thiokol each realized that there was a major problem within the strong rocket booster design they usually started the method of redesigning the joint with three inches of further metal across the tang to grip the interior face to stop rotation. Nevertheless, the senior administration at NASA didn’t name for a halt to shuttle flights and saved treating these issues as a suitable flight danger.[5]

O-Rings & Low Temperatures[edit]

Every area joint was sealed by a pair of O-rings which have been protected by zinc-putty. By design, stress from inside the booster was to push on the zinc putty which might switch the stress to the air within the joint, forcing the O-ring into its seat to kind an hermetic seal. In November 1981 after the second shuttle launch, Jack Buchanan discovered that the first O-ring was barely eroded. Thiokol investigated and located that the outward flexing of the sphere joint delayed the O-ring seating. This result in blow-by, the place as scorching exhaust gases traveled via the zinc-putty, and burned the O-ring. [8]. The trigger for the blow-by couldn’t be decided on the time nevertheless it was deemed as a suitable flight danger after engineers decided that the O-ring may seal even when considerably eroded at increased than launch pressures [8]. In 1985, engineers started to suspect that the blow-by which broken the O-rings was associated to ambient temperatures and have been starting to revamp the sphere joint.

On April 29, 1985, Challenger’s launch for mission STS-51-B skilled the bottom temperatures of their launch historical past on the time, the subsequent lowest could be the day of the explosion throughout STS-51-L’s launch. The launch resulted within the first two O-ring seals fully burned away whereas a 3rd seal practically burned away as effectively. Morton Thiokol engineers, conscious of the problems with the strong rocket boosters, grimly knowledgeable crew member Don Lind that he “got here inside three-tenths of 1 second of dying.” [9]

On the evening earlier than the launch, ambient temperatures have been predicted to be under freezing. Ice had amassed on the launch pad the evening earlier than the launch, elevating issues that ice may harm the shuttle upon liftoff. Nevertheless, as a result of each Thiokol and NASA didn’t have adequate low-temperature testing on the viability of O-ring sealed joints or the zinc putty, they launched the Challenger after their final inspection as a result of the ice seemed to be melting.[4] The inadequate low-temperature testing of the O-ring materials failed to indicate their lack of performance in a chilly setting, ensuing within the failure on launch day. To this point, no shuttle had been launched at a temperature decrease than 53 levels Fahrenheit.

The glass transition temperature of a polymer is the temperature the place a sudden change in modulus happens. As described within the Rogers Fee the O-rings used within the area joint have been 5 occasions extra resilient at 75 levels in comparison with 30 levels Fahrenheit. DuPont Viton was the fabric used for the SBM O-rings. Viton is specified to stay non-brittle after a Three minute publicity at -25 diploma Celsius.[10] Deputy Affiliate Administrator for House Flight Michael Weeks testified, “It wasn’t till after the catastrophe of 51-L that I truly noticed the resiliency knowledge that confirmed that Viton, which is the O-ring materials that we’ve been utilizing, is so sluggish to get well at very low temperatures.”[11] Most significantly, these technical and security issues have been recognized or no less than predicted, however NASA didn’t settle for some engineers’ judgment that the design was unacceptable. Thiokol’s acknowledged place was that “the situation just isn’t fascinating, however is suitable.” [5]

Lack of Correct Communication[edit]

Depiction of the Shuttle Flight Readiness Assessment Course of

The 1986 explosion that destroyed the area shuttle Challenger and killed seven astronauts shocked the nation, however for one rocket engineer the tragedy turned a private burden and created a lifelong quest to problem the bureaucratic ethics that had prompted the tragedy. [12]Roger Boisjoly (1938-2012) was an Utilized Mechanics Engineer at Morton Thiokol and cautioned as early as 1985 that the joints within the boosters may fail in chilly climate, resulting in a catastrophic failure of the casing. Boisjoly had additionally observed that the O-rings eroded as effectively. NASA and Thiokol, nevertheless, determined that, for the reason that O-rings weren’t fully eroded, there was minimal danger. In the summertime of 1985, six months earlier than the Challenger’s deadly launch, Roger Boisjoly despatched a memo to the Thiokols’s Vice President of Engineering. In it, he urged that motion be taken to right away right the O-ring problem. The memo begins with: “This letter is written to insure that administration is totally conscious of the seriousness of the present O-ring erosion downside within the SRM joints from an engineering standpoint.” [13] And later states: “If the identical state of affairs ought to happen in a area joint (and it may), then
it’s a soar ball as to the success or failure of the joint…The end result could be a catastrophic lack of human life.” [13]

Regardless of his efforts, no point out of O-ring points ever made it to NASA higher administration, even with the in depth Shuttle Flight Readiness Assessment. This course of begins at degree IV with the contractors certifying in writing that the components they’re chargeable for are prepared. Then the extent III NASA undertaking managers confirm the readiness of launch parts. Subsequent, the extent II Johnson program supervisor certifies the completion, testing, and checkout of related parts. The method culminates with the Stage I Flight Readiness Assessment, two weeks earlier than a launch. This convention is chaired by the NASA Affiliate Administrator for House Flight and attended by the NASA Chief Engineer, the Program Supervisor, the middle administrators and undertaking managers from Johnson, Marshall and Kennedy, and senior contractor representatives. This process was adopted for the Challenger flight nevertheless it failed to handle objections of Morton Thiokol Engineers in regards to the results of chilly climate on the O-rings, and the issues of Thiokol and Marshall Engineers about O-ring erosion in earlier flights. The O-ring issues within the Stable Rocket Booster joint weren’t even talked about within the Certification of Flight Readiness, signed for Thiokol by Joseph Kilminster.

The ultimate lapse in communication occurred on January 27, 1986, the evening earlier than the launch. A sequence of convention calls have been initiated between Thiokol Engineers (together with Roger Boisjoly), Thiokol senior undertaking administration personnel, and NASA administration to debate the results of chilly temperatures on the O-rings. On this teleconference, Thiokol engineers really useful that the launch be delayed and that Aldrich, Program Supervisor at Johnson (Stage II), learn of the O-ring issues. Thiokol introduced the advice to solely launch inside the knowledge set inside which they’d examined the O-rings: 53 levels or hotter.[5] NASA administration was not happy by the advice. George Hardy, Deputy Director of the Marshall House Flight Middle responded, “I’m appalled by your advice.” Equally, Lawrence Mulloy, the Shuttle Program Supervisor, retorted, “My god, Thiokol. When would you like us to launch – subsequent April?” [5] NASA requested that Thiokol rethink their advice to not launch. This prompted an obvious shift within the launch paradigm; somewhat than needing to show the launch was protected earlier than continuing, NASA directors wished proof that the launch was not protected earlier than agreeing to a delay. This sidestepped engineering issues that have been grounded on the shortage of satisfactory knowledge to show the protection of a launch. Gerald Mason, the Senior Vice President of Operations at Thiokol, demanded a administration determination, telling engineering supervisor Bob Lund to “take off your engineering hat and put in your administration hat.”[5] This led to a administration determination to approve the flight regardless of the engineers’ advice and vehement opposition by Boisjoly and others. NASA higher degree administration was by no means knowledgeable of the potential hazards and the Challenger was launched.

Through the Rogers Fee investigation, Richard Feynman requested administration’s calculated failure charges. They marketed a 1 in 100,000 probability of failure. Nevertheless, the engineers below these managers estimated a failure charge starting from 1 in 50 to 1 in 500. As administration constantly offered chances 1000’s of occasions lower than their engineers offered, Feynman concludes that administration has been “demonstrating an nearly unimaginable lack of communication between themselves and their working engineers.” [14]

Rogers Fee & Congressional Listening to[edit]

Members of the Rogers Fee Arrive at Kennedy House Middle

The Rogers Fee discovered that the lack of the House Shuttle Challenger was brought on by a failure within the joint between the 2 decrease segments of the best strong rocket motor. “The particular failure was the destruction of the seals which are meant to stop scorching gases from leaking via the joint through the propellant burn of the rocket motor.” [15] Manufacturing, meeting, and high quality management nonconformance experiences have been reviewed and no proof was discovered that any flight {hardware} shipped to the launch website fell exterior the bounds of design specs. O-ring resiliency was discovered to be instantly associated to temperature and a compressed O-ring at 75 levels Fahrenheit is 5 occasions extra responsive than a O-ring at 30 levels Fahrenheit. The fee cited that the ambient temperature on the time of launch was 36 levels Fahrenheit, 15 levels colder than another launch. Localized temperature estimates for the coldest level of the joint have been 28 +/- 5 levels Fahrenheit.

In October 1986 the Committee on Science and Know-how started an investigation of the causes of the area shuttle challenger catastrophe. The investigation included ten hearings and an in depth evaluation of the Rogers Fee report. The first objectives of the investigation have been to determine the reason for the accident, future dangers, and what have to be accomplished to return the area shuttle to flight standing. This congressional listening to recognized a number of different excessive danger administration issues at NASA together with communication overload and an over emphasis on price and time constraints.[16]

Aftermath and Moral Classes[edit]

NASA’s organizational tradition and decision-making processes have been the principle components that compromised the undertaking and its security. Roger Boisjoly’s efforts to delay the launch have been futile as a result of miscommunication between the degrees contained in the undertaking, a strong drive to launch, and an elevated tolerance of danger. Consequently, though NASA managers had identified contractor Morton Thiokol’s design of the SRBs contained issues with O-rings since 1978, they failed to handle these points correctly and the Challenger exploded, killing all seven crew members.

Asymmetry of Energy[edit]

The relative sizes of NASA and Morton Thiokol positioned stress on Thiokol to prioritize NASA’s objectives. The strong rocket booster contract made up $400 million of Thiokol’s $2 billion greenback annual income. Shedding this contract would have been a major monetary blow to the corporate. Thiokol obtained the unique contract regardless of not being the bottom bidder, having bid $710 million to Aerojet’s $655 million.[1] Thiokol due to this fact could have felt obliged to not protest selections from NASA, within the hopes of receiving future preferential therapy from NASA. Thiokol could have obtained the contract as a result of affect of Dr. James Fletcher, then NASA Administrator.[1] He had served as president of the College of Utah and owned a number of corporations within the district of Utah wherein Thiokol was primarily based. Giving Thiokol the contract was a strategy to spend money on his house district. Having presumably obtained the contract via favoritism somewhat than advantage little doubt created further incentive for Thiokol to deal with NASA as a buyer somewhat than a consumer, within the hopes of profitable future contracts.

Launch Fever[edit]

NASA confronted a number of exterior pressures that incentivized hurried launch over security, that are collectively known as “launch fever.” President Reagan was as a result of give his State of the Union Deal with the day of the launch and had deliberate on utilizing Christa McAuliffe, a highschool instructor within the Challenger crew, as a speaking level to underscore his promotion of schooling. Halley’s Comet, which passes by the Earth each 75 years, was going to seem later within the 12 months and NASA was launching devices with which to look at the comet on Challenger. The media had more and more painted an image of NASA as an inefficient group unable to maintain its deadlines, which dis-incentivized Congress from budgeting public cash to NASA. The truth is, Congress had lately minimize NASA’s finances. Nevertheless, NASA may regain funds by launching 24 flights per 12 months by 1991.[17] This extremely incentivized NASA to launch shortly somewhat than safely.

NASA Institutional Modifications[edit]

Following the Challenger catastrophe, NASA created the Workplace of Security, Reliability, and High quality Assurance. This workplace was headed by a NASA Affiliate Administrator who reported on to the rating NASA Administrator. The Rogers Fee report particularly recognized NASA’s “launch fever” as a contributing issue to the lack of Challenger. After the discharge of the report, NASA pledged to cut back their launch charge, however a lot of the American public was skeptical, and for good purpose. NASA’s House Shuttle Program started launches in 1981. In its first 5 years, this system averaged 4.6 launches per 12 months. After the lack of Challenger, there have been no launches within the the rest of 1986 nor in 1987. Launches resumed in 1988, and within the 5 years from 1988 to 1992 this system common 5.Four launches per 12 months.

Normalization of Deviance[edit]

Normalization of deviance was a idea proposed by sociologist Diane Vaughan. Vaughan outlined normalization of deviance as “folks inside the group grow to be a lot accustomed to a deviant habits that they do not take into account it as deviant, even supposing they far exceed their very own guidelines for the elementary security”.[18]. There have been a number of incremental deviances amongst Thiokol and NASA. The primary was the difficulty of the flexing of the sphere joint and blow-by. When Thiokol designed the sphere joint, they observed the joint flexed however somewhat than change the design to strengthen the partitions, they added the 2 O-rings. The O-rings have been deemed a criticality 1 part, that means that if the part failed it might result in catastrophic failure of the area shuttle. A criticality 1 part may by no means be backed up by one other criticality 1 part. NASA shouldn’t have allowed the criticality 1 main O-ring to be supported by one other criticality 1 part, specifically the secondary O-ring.[8] In 1978 and in 1979, John Q. Miller and different engineers at Marshall despatched memos to their supervisors, Glenn Eudy (1978) and George Hardy (1979), to inform them that the sphere joint was not protected, that the O-ring was not correctly utilized, and that the secondary O-ring sealing was not at all times assured to work as specified within the contract.[5] Throughout testing, NASA engineers even wrote memos to their supervisor at Marshall House Middle, George Hardy, who didn’t ship on their issues to Thiokol.

Additional deviation got here with STS-2, the second manned shuttle flight which noticed some erosion to the first O-ring. Neither Thiokol nor NASA re-evaluated the designs. Reasonably, Thiokol created a brand new putty to assist forestall O-ring erosion. The engineers examined the bounds of the joint with totally different ranges of abrasion and, because it nonetheless labored when eroded, decided it was a suitable flight danger.[8] The O-rings weren’t changed. In March 1984 on shuttle flight STS 41-B, erosion had grow to be extra frequent and so Thiokol introduced its report on the erosion to Lawrence Mulloy of Marshall House Middle for the Stage III Flight Readiness Assessment for STS 41-C. [5] Mulloy forwarded this data onto Stage I Flight Readiness Assessment as a technical problem, and in response, Mulloy was to conduct a extra thorough evaluation of sealing in every joint of every case. Mulloy requested Thiokol to seek out the bounds of O-ring sealing and the resultant flight danger.[5] Flight STS 51-B in April of 1985 had the worst blow-by resulting in erosion of the secondary O-ring. NASA applied a compulsory pre-launch O-ring evaluation.[5] But Mr. Mulloy and Mr. Lawrence waived the constraint for every flight after July 10, 1985, as much as and together with Challenger.[5] These deviances have been justified by a tradition that incentivized avoiding delays and price will increase as a substitute of addressing technical and questions of safety. Normalization of deviance continued as much as the purpose the place NASA pressured Thiokol and managers pressured engineers to be able to keep launch schedules, regardless of the evident hazard of chilly temperatures.

Options[edit]

After the catastrophe NASA introduced the NASA Security Reporting System (NSRS). The NSRS has since supported all flights and has been expanded to cowl all NASA operations. On this system the NSRS contractor removes figuring out data and forwards solely a abstract of issues to the NASA Headquarters Workplace of Security and Mission Assurance for fast evaluation and investigation. The NSRS is an nameless, voluntary, and responsive reporting channel to inform NASA’s higher administration of issues about hazards. Studies are assured to obtain immediate consideration. If there had been a NSRS system earlier than this catastrophe, Roger Boisjoly would have been in a position to report the issues within the undertaking anonymously; thereby avoiding the organizational limitations to his issues. His place as a NASA contractor wouldn’t have mattered within the nameless submission and thus his issues would have been heard by higher administration and never stifled by NASA degree III managers.

Reparations[edit]

51-L Challenger Crew in White Room - GPN-2000-001867.jpg

The Challenger Settlement paid $7,735,000 the households of Francis R. Scobee, Ellison S. Onizuka, Gregory B. Jarvis, and Sharon Christa McAuliffe. Reparations have been cut up 40-60 between Morton Thiokol and america Authorities. Households of Ronald E. McNair and Judith A. Resnik settled with Morton Thiokol privately for an undisclosed quantity. Michael J. Smith’s spouse Jane Smith, sued Morton Thiokol and america authorities as a substitute of accepting the settlement provided to the opposite astronauts. Attorneys representing america authorities cited the Feres Doctrine which claims navy personnel or their dependents can not sue the Authorities over accidents or dying that occurred whereas on lively service. Attorneys for Jane J. Smith, argued that her husband was not on common navy task and had no navy duties on the time of his dying. U.S district Choose Patricia Fawsett dominated that Michael Smith’s dying occurred “throughout exercise incident to his navy service” and eliminated america Authorities as a defendant within the case.[19]

Roger Boisjoly Submit-Challenger[edit]

Roger Boisjoly was crammed with grief following the explosion of the House Shuttle Challenger. He suffered from extreme complications, melancholy, and insomnia. Three weeks following the catastrophe, Boisjoly gave a confidential interview to NPR journalist Daniel Zwerdling that depicted the choice making course of at Morton Thiokol and NASA that led to the catastrophe.. It was solely revealed after Boisjoly’s dying that he was the topic. Throughout this interview, Boisjoly was quoted as saying “I fought like Hell to cease that launch. I am so torn up inside I can hardly discuss it, even now.” [20] In 1987, Boisjoly filed a lawsuit in opposition to Morton Thiokol accusing them of fraud, negligence, manslaughter, racketeering, defamatory statements, and untruthful testimony to a Presidential investigating fee and Congress. Boisjoly filed a further swimsuit in opposition to NASA. Each lawsuits have been unsuccessful.[21] Within the early 1990’s, on the urging of his therapist, Boisjoly started touring to engineering colleges around the globe talking about his experiences, moral determination making, and the significance of trusting your knowledge. When talking to his spouse Roberta he stated: “That is what I used to be meant to do, to have impression on younger folks’s lives.” He continued to answer letters and emails from school college students up till his dying in 2012.

References[edit]

  1. abcd Hoover, Kurt; Fowler, Wallace. “Doomed from the Starting:The Stable Rocket Boosters for the House Shuttle”. Texas House Grant Consortium. http://www.tsgc.utexas.edu/archive/common/ethics/boosters.html. Retrieved Might 1, 2014. 
  2. On-line Ethics Middle for Engineering. [www.onlineethics.org/Topics/ProfPractice/Exemplars/BehavingWell/RB-intro.aspx “Roger Boisjoly-The Challenger Disaster”]. Nationwide Academy of Engineering. www.onlineethics.org/Matters/ProfPractice/Exemplars/BehavingWell/RB-intro.aspx. Retrieved Might 1, 2014. 
  3. Rogers Fee (June 6, 1986). “Report of the Presidential Fee on the House Shuttle Challenger Accident, Chapter IV: The reason for the accident”. http://historical past.nasa.gov/rogersrep/v1ch4.htm. 
  4. ab Division of Philosophy; Division of Mechanical Engineering. “Engineering Ethics: The House Shuttle Challenger Catastrophe”. Texas A&M. http://ethics.tamu.edu/ethics/shuttle/shuttle1.htm. Retrieved Might 1, 2014. 
  5. abcdefghijokaylm Rogers Fee (June 6, 1986). “Report of the Presidential Fee on the House Shuttle Challenger Accident, Chapter VI: An Accident Rooted in Historical past”. http://historical past.nasa.gov/rogersrep/v1ch6.htm. 
  6. Investigation of the Challenger Incident-Committee of Science and Know-how:https://www.gpo.gov/fdsys/pkg/GPO-CRPT-99hrpt1016/pdf/GPO-CRPT-99hrpt1016.pdf
  7. Investigation of the Challenger Incident-Committee of Science and Know-how:https://www.gpo.gov/fdsys/pkg/GPO-CRPT-99hrpt1016/pdf/GPO-CRPT-99hrpt1016.pdf
  8. abcd Vaughan, Diane (1997). The Challenger Launch Resolution: Dangerous Know-how, Tradition, and Deviance at NASA. College Of Chicago Press. ISBN 0226851761. 
  9. Wright, Rebecca (Might 27, 2005). “Oral Historical past Transcript”. NASA Johnson House Middle Oral Historical past Challenge. https://www.jsc.nasa.gov/historical past/oral_histories/LindDL/LindDL_5-27-05.pdf. Retrieved Might 9, 2017. 
  10. Dupont Viton- Specs and Materials Properties:http://www.dupont.com/industries/automotive/press-release
  11. Investigation of the Challenger Incident-Committee of Science and Know-how:https://www.gpo.gov/fdsys/pkg/GPO-CRPT-99hrpt1016/pdf/GPO-CRPT-99hrpt1016.pdf
  12. Vartabedian, Ralph (February 07, 2012). “Engineer tried to halt shuttle launch”. Misplaced Angeles Occasions. http://articles.latimes.com/2012/feb/07/native/la-me-roger-boisjoly-20120207. Retrieved Four Might 2014. 
  13. ab Boisjoly, Roger (July 31, 1985). “SRM O-Ring Erosion/Potential Failure Criticality”. Rogers Fee. https://historical past.nasa.gov/rogersrep/v4p807.htm. Retrieved Might 9, 2017. 
  14. Richard, Feynman (June 6, 1986). “Appendix F – Private observations on the reliability of the Shuttle”. Rogers Fee. https://science.ksc.nasa.gov/shuttle/missions/51-l/docs/rogers-commission/Appendix-F.txt. Retrieved Might 9, 2017. 
  15. The Reason for the Accident- Findings:https://historical past.nasa.gov/rogersrep/v1ch4.htm
  16. Investigation of the Challenger Incident-Committee of Science and Know-how:https://www.gpo.gov/fdsys/pkg/GPO-CRPT-99hrpt1016/pdf/GPO-CRPT-99hrpt1016.pdf
  17. Rogers Fee (June 6, 1986). “Report of the Presidential Fee on the House Shuttle Challenger Accident, Chapter VIII: Pressures on the System”. http://historical past.nasa.gov/rogersrep/v1ch8.htm. 
  18. Villeret, Bertrand; Vaughan, Diane (Might 2008). “Interview : Diane Vaughan”. Advisor. http://www.consultingnewsline.com/Data/Vie%20du%20Conseil/Le%20Advisor%20du%20mois/Diane%20Vaughan%20(English).html. Retrieved Might 3, 2014. 
  19. Jane Smith Go well with- Smith v. Morton Thiokol-https://casetext.com/case/smith-v-morton-thiokol-inc
  20. Remembering Roger Boisjoly: He Tried To Cease Shuttle Challenger Launch – http://www.npr.org/sections/thetwo-way/2012/02/06/146490064/remembering-roger-boisjoly-he-tried-to-stop-shuttle-challenger-launch
  21. Engineer Who Opposed Launching Challenger Sues Thiokol For $1 Billion – http://www.nytimes.com/1987/01/29/us/engineer-who-opposed-launching-challenger-sues-thiokol-for-1-billion.html?pagewanted=1


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