challenger disaster blamed on o-rings, pressure to launch ...

by:Ultimate     2020-11-27
The Challenger accident was caused by the failure of NASA and booster manufacturers to improve the solid rocket booster joint, although it has been warned for eight years that it is dangerous, the presidential commission investigating the disaster said in its final report yesterday.
One of the main reasons the space agency failed to notice these warnings, the report said, was due to \"excessive\" pressure
Ambitious \"schedule of 24 shuttle flights per year by 1990.
It said the pressure caused such a widespread disruption that the shuttle project could soon collapse even without an accident.
The Commission\'s research goes far beyond the problem of joints.
It found serious defects in NASA\'s overall safety plan, the system to check the flight hardware, the crew training, and the test of the orbiter engine, its paper work and sudden and disruptive changes in flight payload to suit commercial customers.
In addition, the company says spare parts from one shuttle to another are being eaten away and project technicians are working too tired.
All of these factors hurt flight safety, the report said.
The hard-worded report calls for a comprehensive overhaul of NASA\'s management practices.
It also urged the establishment of several safety review teams within and outside the agency to ensure that booster joints were redesigned to meet the strict standards set out in the report.
It also urged the re-use of the more traditional unmanned-consumed rocket launch payload and concluded that \"reliance on the space shuttle\" put relentless pressure on NASA. \"The 256-
The page report, which includes photos, charts, and charts, lists a very detailed and well-documented case that proves that NASA\'s management practices have failed to address various safety issues, including joints, over the years.
\"I think it\'s a national tragedy in a sense, and a lot of us should be responsible for that,\" committee Chairman William P ·
Rodgers said yesterday when the White House formally submitted a report to President Reagan.
\"I think, in a sense, the government, Congress, the media ---
We are too optimistic to accept this fact. shuttle]is operational.
I don\'t think it\'s good to try to evaluate blame. But Lawrence B.
Mulloy, head of the booster program for Marshall Space Flight Center in Huntsville, Alabama.
The Marshall Center itself is the most serious trouble point in the report.
According to the report, the panel found that some of the testimony of the committee was false.
Marshall did not communicate serious security issues to NASA headquarters, the report said.
Malloy was removed from his previous job earlier, and Rogers called it \"constructive\" yesterday \".
\"Historically, NASA\'s attitude reflects the position that \'we can do anything, \'although it may be basically correct, but NASA\'s optimism must be said by realizing it can\'t do the report.
The Challenger and the destruction of sevenCrew January.
The report said that 28 was an unnecessary accident, citing not only ignored warnings, but also some close-range calls in flight since the launch of the second space shuttle in 1981.
\"The trend of not recognizing and reporting can only be described as\" quality evasion \"in NASA\'s terminology, which is an unavoidable problem that the project has failed to rule out.
\"If the project is running properly, the Challenger accident may be avoided,\" the report said . \".
\"The space shuttle\'s solid rocket booster problem began with the wrong design of its joint, and with the first time NASA and contractor management did not recognize it as a problem, the report said:\" then failed to fix, ultimately, it is considered an acceptable flight risk. \".
The Commission\'s main findings include: * the cause of the Challenger accident was identified as O-
Ring on the right
Manually supercharge the joint to control the hot gas pressure generated by burning rocket fuel.
The flame burns through the booster wall, causing the booster to tear from the external tank, the external tank to break and overflow highly flammable liquid hydrogen and liquid oxygen.
* Low temperature on launch day to harden rubber O
The rings are so much that they cannot remain sealed in the joints that due to poor design, the rings open the gap and should be sealed in the first second after ignition.
* Neither NASA nor booster manufacturer Morton tiokor
Understand how the joints work and do not test the joints in a reasonable simulated flight.
* NASA and Thiokol are both playing \"a Russian roulette\" and continue to fly the space shuttle despite known problems.
They \"obviously accepted the risk of escalating because they escaped the risk last time.
Although NASA officials have repeatedly told the committee that cold temperatures and O-
During the previous flight, the board found the opposite problem and said NASA should do the same.
In all four flights below 65 degrees, O-rings.
In contrast, only 3 of the 20 flights with warmer weather experienced O-ring damage.
* Senior NASA officials in Washington received a copy about O-
Flights in August 1985 were grounded long enough to correct the problem.
But they don\'t.
* The commission was \"surprised\" that in all the testimony it heard, \"NASA\'s security personnel were never mentioned.
A report called the silent security program says no security person has been invited to key meetings leading to the launch.
The cuts in security department personnel have weakened its role, and at the Marshall and Kennedy space centers, the security office is supervised by the people they should check.
* The night before the launch, when Thiokol management reversed no
Go recommends its engineers that the switch is not based on reasonable safety considerations, but \"to meet the main customers \".
* The morning of January.
28, when the orbiter manufacturer Rockwell International suggested not to launch because of the ice on the launch tower, the level of concern expressed by the company was vague ---
But NASA should scrub it anyway.
The specific recommendation of the Commission is: * to cancel or redesign the joint forces.
A group of national research committees should oversee the work.
NASA is already doing this.
* Re-organize the space shuttle program so that managers are responsible for the whole project, not for their respective NASA centers, and involve more astronauts in the management.
* Review the most critical components of the space shuttle to ensure that they are as safe as possible and verify the findings by an independent team of the National Research Commission.
* Create a larger, more robust office of safety, reliability and quality assurance led by an Assistant Administrator who reports directly to NASA administrators.
* Improve communication between Marshall and other NASA centers and keep a better record of flight preparation meetings.
* Improve tyres, brakes and steering systems that are critical to landing safety.
Before the improvement, only landing at Edwards air base.
* Re-check if crew escape means are provided once the orbiter does not have a solid rocket. (
It is not feasible to escape before this point. )
* Establish a strict system to maintain highly critical shuttle components and have sufficient spare parts to stop devouring one orbiter to supply the other.
The Committee urges NASA to report to the President, within a year, on its progress in implementing the proposals.
Perhaps the worst chapter in the report is about the history of the booster joint design.
Under the heading \"accidents rooted in history\", This chapter shows that the Challenger disaster dates back to 1977, four years before the first shuttle flight.
Marshall\'s engineers are evaluating early laboratory tests of the joints that show that the gap opens when under pressure, contrary to the assumption of the Thiokol designer.
Thiokol objected to the findings.
In 1977, Marshall engineers Leon Lei and John Q.
Miller, who wrote a report calling for a redesign of the joint venture, said, \"We believe there is no justifiable reason to not design as per accepted standards.
The redesign, they say, is \"a mandatory measure to prevent heat leakage and cause catastrophic failure \".
NASA rejected the judgment of engineers.
In 1980, a NASA team was appointed to review the safety of the space shuttle in preparation for its first flight.
The Ring \"is not enough to provide the reliability of the operating procedure or to provide sufficient confidence in the safety factor.
\"Nevertheless, NASA announced that the joints were safe enough to fly and continue to fly, although the Thiokol engineer warned in the memo that a\" disaster \"could occur \".
\"The report said that for many years, there has been a slow increase in concerns about this issue until 1985, when a series of O-
Case of ring damage including serious condition in 53-
Thiokol re-checked the reliability of the seal due to weather.
The company tested the temperature to O-
The ring elasticity, with the expansion of the joint gap, is able to bounce back from the Extrusion conditions and keep the seal.
The results show that elasticity decreases at 75 degrees, and at 50 degrees, there is almost no elasticity.
The report said: \"As the number and severity of joint issues increase, NASA has minimized these issues in its management briefings and reports.
The position of Thiokol is that \"the conditions are not desirable but acceptable.
\"At any time, is it recommended by management to redesign United Airlines, or to call for the shuttle to stop before the problem is resolved,\" the commissioners wrote . \".
\"The report does not state what happened to the crew when the cabin crashed.
However, some members privately stated that there was reason to believe that the crew might be alive and awake within the first few seconds of the Cabin fire.
They say the loss of pressure and oxygen, as well as the power of a quick roll, could make the crew unconscious after 10 to 20 seconds.
The seven crew members killed in the accident were Shuttle Commander Francis R. (Dick)
Pilot Michael J. Scoby
Task expert Ellison S. Smith
Resnick and Ronald E.
Gregory B McNair, payload expert
Jarvis and space teacher Krista mcliffe
In the section called the silent security plan, the Commission recorded that there was almost no security plan in the pre-launch decision-making --making.
The report specifically points to the 1983 change requested by Martin reens, director of safety, reliability and quality assurance at the Johnson Space Center in Houston, which eliminates significant reports from NASA\'s top officials on flight safety issues.
\"With this action, level 2 [
Top shuttle project manager
Lost all knowledge of safety, operations and flight schedule issues
Marshall promotes middle-level managers such as officials]
\"The report said.
Raines has said that the change is to \"streamline the system\" after the system is put into use \".
\"Marshall\'s safety program\" should track and discover the reasons for the \"significant change in performance\" of booster joints starting in January 1984.
Another failure of the security plan cited in the report is the ongoing uncertainty surrounding \"criticality ---
Potential risks-
Booster joint
Although as early as 1982, the joint forces were officially classified as forces that pose the greatest risk to missions and crew, most of the papers done by thiokol and Marshall on this issue listed it as critical ir--
This means that there is backup hardware or redundancy in the system to reduce risk, though not.
\"As a result,\" the report says, \"a wise decision --
The key manager is impossible.
\"As early as March 7, five weeks after the accident, the problem assessment system operated by Marshall Rockwell contractors still listed the joint as a critical R. Jesse W.
At the time of the accident, Moore, head of the space shuttle program, was \"wrongly informed\" of what Marshall was doing to address joint issues and joint risk issues, the report said.
According to the report, after President Reagan announced on July 4, 1982 that the space shuttle was put into use, in determining the flight schedule, \"NASA did not provide sufficient resources to achieve this goal.
\"So even in a modest 9-
Mission rate in 1985, the evidence shows that NASA will not be able to complete 15 scheduled flights of 1986 kilometers.
The team urged NASA to develop strict new ground rules for flight rates based on \"a realistic assessment of what NASA can do safely and well.
\"NASA allows the creation of disruption, which means that\" the end of the production chain: Crew training \"is getting squeezed,\" the report said.
It quoted astronaut Henry Hartsfield as saying, \"If we do not have an accident, we will be on the wall. . . .
For the first time, someone had to stand up and say we had to miss the launch because we would not have the crew trained.
\"This includes the disruption caused by\" development issues, financial difficulties or changes in market conditions \"when the shuttle customer requested a change in the launch date.
NASA usually accepts these requirements and has never imposed penalties on \"customers\", the report said.
Harold droughgan, a Johnson Space Center official, told the commission that even a small change in goods would take a lot of time if delayed.
\"Completing more urgent immediate requirements shifts people\'s attention to what is happening throughout the system,\" the report said . \".
\"In many ways, the system is not prepared to meet the \'option\' schedule.
\"At the Kennedy Space Center, many contract employees work 72 hours or more a week and work 12-on a regular basis-
The report said: \"hour shift.
\"During the attempt to launch mission 61C in January, the potential impact of this overtime on safety became apparent.
6, 1986, when fatigue and displacement are considered to be the main factor contributing to a serious event, the event involves the depletion of liquid oxygen that occurs less than five minutes before scheduled departure.
\"When the accident occurred, the problem of spare parts also reached its peak.
By last January, \"only 32,000 of the 50,000 items required (65 percent)
\"Cutting funds\" led to a significant delay in the purchase of spare parts.
\"For NASA, this is a\" basic way of working \", that is, removing parts from one shuttle orbiter to fit on another.
\"This approach is costly, disruptive and presents an opportunity for component damage. . .
Is a potential threat to flight safety.
\"I think if we keep trying to fly, we\'ll get down on our knees this spring because of this issue,\" said Horace Lambeth, director of engineering for the Kennedy Space Shuttle, telling the commission in an interview.
According to the report, as of spring 1986, the shuttle logistics plan was about a year behind.
\"Unless logistics support is improved, even if three
The fleet of orbiter is in danger.
One of the \"serious problems\" among space shuttle technicians, the report says, is that they believe they may be \"punished\" or even unemployed if they report accidental damage to the shuttle.
As a result, \"reports of accidental damage are inconsistent.
\"In the Appendix to the report, the panel severely criticized NASA for recording the system in which the space shuttle handled the problem and concluded that the system itself was an issue.
\"The number of defective paper works ---
About 50%--
This is unacceptable . \"
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