nasa acknowledges cold affects booster seals

By PHILIP M.
Special report from the New York Times.
1986 this is a digital version of an article from The Times Print Archive, before it starts online in 1996.
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Space agency today acknowledged that cold temperatures reduce the effectiveness of key safety seals designed to prevent the escape of hot air and flames through the joint of the shuttle booster rocket.
Richard P. questioned this recognition.
Feynman, Nobel Prize winner
The California Institute of Technology\'s award-winning physicist, at a public hearing by the Presidential Commission, is investigating the cause of the January explosion that destroyed the Challenger space shuttle. 28.
The agency maintains that experts believe that, despite the unusually cold weather during the launch and the night before, the seals will still operate safely.
But an official also admitted that the day before, the builder of the bootsmith suggested that cold weather could cause problems with the seals. Impromptu Ice-
Water TestIn has previously issued a public statement on this issue and other issues, and NASA officials have issued conflicting statements on the reliability of key space shuttle equipment and the agency\'s disaster preparedness work
While no one considers these false statements to be deliberate, they raise questions about how strict the control of the space shuttle program is by senior officials and how it is affected by the pressure, to keep the project on schedule and economically competitive. [
News Analysis, page 12]
After lunch break today, doctor.
Feynman told the panel that he had just conducted an impromptu experiment with the rubber material used to seal the huge round ring of the rocket joint.
He said he dipped a piece of material into ice water and found that it lost its elasticity, a factor that space officials say is important for the effective operation of O-ring seals.
AdvertisementHe later asked NASA officials if the low temperature would increase the likelihood of seal failure, which is not true.
Advertising Lawrence B.
Mulloy, project manager at Solid-
A fuel booster rocket at the Marshall Space Flight Center in Huntsville, Alabama.
It is acknowledged that low temperature may slow down the speed at which the O-ring forms a tight seal after being hit by hot gas.
This in turn increases the erosion of the O-ring under the pressure of the gas rushing, he said.
When the doctor asked
Mr Feynman, if the temperature is lower than the temperature where the O-ring should not be used
The procurement specifications indicate that they can operate safely at temperatures of minus 30 degrees, Mulloy said.
But he said the test showed that the ring lost its elasticity as the temperature dropped to 50 degrees Fahrenheit, adding that Morton tiokor
It built the booster rocket and submitted data to NASA the day before its launch, indicating further loss of elasticity at 20 or 25 degrees Fahrenheit.
He said Thiokol\'s data suggest that the shuttle should not be launched at temperatures below previous flights.
Nevertheless, he added that NASA experts believe that O-rings will operate normally under conditions at launch.
NASA officials said the outside air was about 38 degrees Fahrenheit at the time of launch, but did not say how the temperature compared to the previous launch.
As we all know, previous launches did not raise so many questions about the impact of cold weather.
Temperatures plummet to mid-term
20 The night beforeWilliam P.
Former Secretary of State Rogers, who is in charge of the committee, cut off further inquiries about the weather and suggested that the topic be discussed more fully at committee meetings at the Kennedy Space Center on Thursday and Friday.
Although the O-ring seal was the main focus of today\'s hearing, NASA officials warned that the possible failure of the O-ring was not necessarily the cause of the accident.
Many theories have been put forward about the cause of the accident.
The photos released by NASA seem to show a flame coming out of the right --
The hand booster raises the possibility that the flame somehow triggers a huge explosion in the fuel tank outside the shuttle.
The Flame appears to come out from the rocket near the seam, fixed together with steel pins, between two steel sections sealed with O-rings and other barriers to prevent gas from leaking from the seam.
Some analysts have speculated that seals may have given way under the erosion pressure of high-temperature gases, or that cold weather may cause seals to fail.
Others believe that cold weather may affect other parts of the shuttle in some way, or on previous flights, undiscovered cracks may be formed in reusable booster segments
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Aviation Weekly recently reported that NASA investigators believe that once the gas starts to escape from the side of the booster, they cut off the connection to hold the booster in place, causing it to rotate and hit the tank.
Another possible explanation made publicly for the first time at today\'s hearing is that holes used to test O-ring seals may leak.
These holes lead to one part between the two seals, one main seal for stopping the gas and one spare seal.
The technician may have human error, open the test hole, pressurize the gap, and determine whether the two seals remain normal.
Then they should close the holes with screws-like plug.
Their work should be checked by contractors and air force personnel, but if no human error is found, the plug is left out, \"that will be the source of the leak, sir.
, Roy in Stacey feeder
Other analysts believe that manufacturing defects can also cause test ports to fail.
NASA asked today\'s hearing to deal with the implications raised in the internal memo, which was disclosed in The New York Times on Sunday, budget analysts and engineers at the agency have been concerned last year about O-ring erosion observed on some previous flights.
The hearing was particularly focused on the memo written by Richard C.
Cook, a budget analyst at NASA\'s auditor general\'s office, warned in July 23, 1985 that the memo said flight safety was \"compromised by the potential erosion of seals \", \"The failure in the launch process will certainly be disastrous.
A group of acting witnesses testified
Cook\'s concerns have been exaggerated, and senior NASA engineering experts and managers have carefully dealt with the issue of seal erosion, which has been reduced in 1985.
NASA officials did not specifically question the budget analyst\'s claim that seals had been eroded, but believed that more capable professionals were safe enough than he thought. Mr.
Cook works in the resource analysis department, which negotiates with the agency\'s engineers to determine the impact of hardware issues on the budget.
Branch president Michael B.
Mann told the panel that the possible budget issue involved in seal erosion was that he gave Mr.
Cook was a new employee. After Mr.
Mr. Cook reported that the engineers thought the problem was very serious.
Mann said he checked with the engineer and came to the conclusion that \"perhaps the memo exaggerated their concerns.
Concerns sent to other smr.
Mann said he forwarded the memo to the superior and the space flight office and said that he believed that the issues raised were being dealt with \"through appropriate technical channels. \'\' Jesse W.
Moore, head of the space flight office, said he had not seen
Until Cook\'s memo on Sunday. Mr. advertising
Mulloy, the agency\'s chief witness on erosion, said about 228 joints were removed after previous flights.
He said that there has never been a failure of both seals, but 22 joints show some erosion of the primary O-ring, and 10 joints actually have soot behind them.
Only once, he said, the secondary O-ring was also eroded, but it was effectively sealed anyway. Mr.
Mulloy testified that erosion was \"not disturbing from a safety point of view,\" as testing and analysis indicated that seals were likely to suffer three times the observed erosion and were much higher than rockets. Mr.
Cook testified that he interviewed NASA engineers in July 1985 and found them worried about the erosion of seals.
He suggested a solid budget reduction-
The fuel booster program may affect NASA\'s final judgment.
However, NASA officials say there is sufficient emergency funding to repair seals if deemed necessary.
A version of this article appears on page A00001, national edition, February 12, 1986, with the title: NASA acknowledges that cold can affect booster seals.