Posted on 02/03/2003 11:54:17 PM PST by kattracks
s early as 1997, a senior NASA engineer warned that hardened foam popping off the external fuel tank on the Columbia shuttle had caused significant damage to the ceramic tiles protecting the vehicle from re-entry temperatures.
The warning was sure to receive new scrutiny after NASA said yesterday that its investigation into the cause of the destruction of the space shuttle on Saturday was focusing on damage to tiles that may have been caused by foam or ice or a combination of the two. NASA officials also acknowledged that they might have underestimated the potential seriousness of damage sustained by the tiles when the shuttle lifted off.
Gregory N. Katnik, a NASA engineer at Cape Canaveral, said in a report dated Dec. 23, 1997, that the Columbia had sustained damage to more than 300 tiles on a recent flight. The inspection after a Columbia mission in 1997 showed that the tiles had sustained damage that was "not normal," Mr. Katnik said.
In a number of other shuttle flights, tile damage from falling foam also caused smaller amounts of damage, but NASA decided that over all, the problem did not threaten the survival of its spacecraft.Now the agency is re-examining that assumption as it struggles to explain the mystery of how the Columbia broke up as it soared back into the atmosphere.
Ron D. Dittemore, the shuttle program manager, told a news conference yesterday that damage to the tiles was the leading focus of the investigation, but he cautioned that what appeared to be the most likely solution might prove illusory as the complex inquiry moved ahead.
"There's some other event; there's some other missing link that we don't have yet that is contributing to this temperature increase," Mr. Dittemore said. "It's a mystery to us."
But new evidence that surfaced yesterday suggested that damage to the tiles may have been more severe and covered a wider area than first estimated.
A videotape made by a team of NASA scientists at the Jan. 16 liftoff appeared to show a bushel-basket-sized chunk of debris breaking away from the external fuel tank and striking the fragile protective tiles on the underside of the left wing. A NASA analysis suggested the impact could have damaged a swath of tile as large as 7 inches wide and 32 inches long, according to an agency memorandum made public yesterday.
The possibility that damaged tile could have caused the ship to break apart when it re-entered the atmosphere was supported by several outside experts in aerodynamics. They said in interviews that even slightly damaged tiles perhaps only roughened or cracked could generate turbulence near the tiles during the tremendous speeds of re-entry, creating potentially dangerous heating of Columbia's aluminum skin.
"There is a possibility that just damage to the tile to the point that they are rougher could create increased heating," said Dr. Michael Holden, director of the Calspan University of Buffalo Research Center in New York, which does aerodynamic testing of the shuttles.
"If it went turbulent, you'd be in more jeopardy," possibly affecting the survival of the entire craft, Dr. Holden said.
While NASA has had trouble working out the details of how the foam impact could have led to the breakup, the accumulating evidence could force the agency to alter its initial determination that the damage seen on the Columbia was not significant, said Dr. Edward Crawley, chairman of the department of aeronautics and astronautics at the Massachusetts Institute of Technology.
"It's possible that more insulation fell off than they thought," Dr. Crawley said. "It's possible that it hit in a way that caused more damage than their model suggested."
But it is also possible, Dr. Crawley said, that "there's still sort of a missing event here" the link that will make a new pattern, and a new theory for the catastrophe, emerge.
The newly released NASA video shows a whitish object soaring backward, striking the Columbia's left wing and bursting into a cloud of dust. The oblong chunk appears to be the size of the shuttle's astronaut hatch, which measures about 40 inches by 40 inches.
Mr. Dittemore said NASA's analysis determined that the piece probably weighed just under three pounds, though he said that new and more intensive work was being done that could revise that number. With a range of assumptions about the exact angle at which the piece ricocheted off the spacecraft, he said, NASA determined that anywhere from a single tile to a swath 32 inches long could have been damaged.
He said that NASA's computer model generally predicted more damage than would actually take place. The debris was first noticed the day after the shuttle liftoff when engineers were reviewing film. But Mr. Dittemore said no one on NASA's study team initially thought the damage posed a serious concern.
"At the time I was not aware of anybody that had those feelings, at least to the point where they would want to come forward and identify that there's still something that they think remains undone," Mr. Dittemore said.
Reports prepared during the flight of the Columbia were released yesterday by NASA. They showed that the falling debris occurred 81 seconds into the flight and was first identified the day after the liftoff."At approximately 81 seconds Mission Elapsed Time, a large light-colored piece of debris was seen to originate from an area near the ET/Orbiter forward attach bipod," the report said. "The debris appeared to move outboard and then fall aft along the left side of the Orbiter fuselage, striking the leading edge of the left wing."
The report said that more detail would come from analysis of high-speed tracking films.
A report two days later said analysis of the films could not identify individual tiles, but it concluded, "no indications of larger scale damage were noted."
On Jan. 28, a report said that a study of films and analysis of temperatures onboard the spacecraft indicated a potential for significant damage to the tiles. But it concluded that there was "no safety of flight issue."
But the idea that somehow the tile was extremely vulnerable to damage received support from the earlier report on similar damage.
In 1997, Mr. Katnik, the senior NASA engineer, worked in a division that analyzed data from inspections of the shuttles. He is now a technical manager in the Space Shuttle Program Launch Integration Office at the Kennedy Space Center.
He said on the 1997 mission the shuttle sustained a significant amount of damage to its heat tiles. In a normal mission, a shuttle will sustain damage to up to 40 tiles because of ice dropping from the external tank and hitting the tiles, Mr. Katnik reported. But on that mission, he said, "the pattern of hits did not follow aerodynamic expectations, and the number, size and severity of the hits were abnormal."
Inspectors counted 308 hits. Of those, 132 were "greater than one inch," Mr. Katnik said. Some of the hits measured up to 15 inches long with depths of up to one-and-a-half inches. The tiles were only two inches deep, so the largest hits penetrated three-quarters of the way into the tiles, he noted.
The damaged tiles were mostly around the shuttle's nose. After the mission, more than 100 tiles were taken off because "they were irreparable," Mr. Katnik said.
The report went on to speculate as to why the foam dropped off. As it turned out, to be environmentally friendly, NASA had eliminated the use of Freon in foam production, Mr. Katnik reported. The Marshall Space Flight Center in Huntsville, Ala., later concluded that the absence of Freon led to the detachment of the foam.
While the formulation was later improved, the episode revealed potentially dangerous new ways in which tiles could be damaged."The tiles still had plenty of material left," Mr. Katnik said in an interview yesterday. "There was a margin of safety."
Nonetheless, he said, the shuttle "was coming back with an irritating amount of damage that we had to repair."
GANG-GREEN really know well how to put on an intense political "full court press" and it can make any politician feel totally under seige!!! I know first hand about this!!!
I don't think C.O. is as much attacking the Bushes as he is disappointed they still don't exhibit the political courage to fight this crap in effective ways. Remember, I met him (C.O.) at the biggest protest in Sacto since the Vietnam anti-war demonstrations, trying to support BushII and stop the Algore/Kazinsky election theft! (lesser of two evils, as always)
Enjoy you fishin trip and hurry back safely.
Given that EPA had five years (or more) of data on MTBE: its volatility, its byproducts of combustion, how it condenses in water, how it diffuses through plastic, how it precipitates in rain, its effect on seals and hoses, hell they even predicted how many vehicles might catch fire... and THEN the majors demanded indemnification before supporting the Amendments to the Clean Air Act. Do you really mean to tell me that nobody in the Bush Administration knew and this was all a matter of political pressure? Are you telling me that nobody was smart enough to see the potential environmental harm and turn this thing against the greenies? Don't you remember who coordinates how those greenies get their money?
Whether negligently accountable or criminally culpable, the onus is the same.
Within hours of this terrible disaster there were some on FR claiming that the disaster was the result of NASAs incompetence, that the disaster was avoidable and that the cover up had already began. They have offered up memos, doctored photos and wild rumor as evidence.
In order to be true than we must also assume that the seven astronauts who died were fools or somehow duplicitous in their own deaths. Are we expected to believe that the knowledge of a few rumor mongers on the internet is greater then that of those who flew on Challenger?
Are we to believe that these seven astronauts were not aware of the foam problems on the shuttle program or the effects of budget cuts on the program? Are we to believe that they were foolish enough to fly a platform into space that was doomed from the beginning as some on FR claim?
If we accept their speculation then we must also assume that their fellow astronauts, walking the woodlands of east Texas looking for their remains, will not seek to discover the real cause of their deaths, but will work to cover up for NASA. Do you really believe this?
Is this what weve come to on FR? This doesnt just smear NASA, it smears the seven brave people we honor today.
I'm just curious if you also think it's an insult to homicide, robbery, or assault victims when their family and friends exercise their God given talents to investigate who
carried out those crimes, when the police are unable to asertain who did it? In this instance we have an agency that has two vested interests, full disclosure and the
welfare of the agency itself. Why it would be an insult to the astronauts to make sure they weren't short-changed in the process, is beyond me.
I have seen the product of your logic before. It's generally interesting, but seldom very sound. Don't give up.
Within hours of this terrible disaster there were some on FR claiming that the disaster was the result of NASAs incompetence, that the disaster was avoidable and that the cover up had already began. They have offered up memos, doctored photos and wild rumor as evidence. In order to be true than we must also assume that the seven astronauts who died were fools or somehow duplicitous in their own deaths. Are we expected to believe that the knowledge of a few rumor mongers on the internet is greater then that of those who flew on Challenger?
Are we to believe that these seven astronauts were not aware of the foam problems on the shuttle program or the effects of budget cuts on the program? Are we to believe that they were foolish enough to fly a platform into space that was doomed from the beginning as some on FR claim?
If we accept their speculation then we must also assume that their fellow astronauts, walking the woodlands of east Texas looking for their remains, will not seek to discover the real cause of their deaths, but will work to cover up for NASA. Do you really believe this?
Is this what weve come to on FR? This doesnt just smear NASA, it smears the seven brave people we honor today.
You find this embarassing? This is the product of your logic? I do feel sorry for you.
Been out looking for work all day...
The early astronauts were real pains in the ass for the engineers and flight directors, demanding this and that be added to the vehicles (like escape hatches and manual control options). These guys trusted their own judgement, and weren't dazzled by gadgetry or hollow assurances.
I don't think the new guys have the same self-assurance, the same "yank", the same war-hardened character that would spurr them to defy the bigshots if they discerned something was amiss--"step aside, son: there's a hundred more waiting to take your spot." Not the same grit. More of a reticent 'team player' attitude, and an unwise trust in 'the system'.
The old-timers knew they were lab-rats and monkeys, but they did things on their own terms: the program needed them more than they needed the program.
Bearing that observation in mind, I think it somewhat safe to surmise that yes, these guys could be foolish enough to fly a doomed platform into space: exactly what Grissom, Glenn, Shirra, Carpenter, Cooper and Shepard refused to do.
The problem with your thesis is that EXACTLY such a cover-up has happened before. It wasn't until Richard Feynman (a maverick physicist from Cal-Tech) was brought in from outside NASA, that the truth about the Challenger disaster came out. As I recall, NASA suppressed the complaints of Morton Thiokol engineers that the cold temperature performance of the o-rings in the solid rocket boosters was inadequate. The engineers recommended that the Challenger launch should be scrubbed below a specific air temperature and were over-ruled. As whistleblowers their jobs were threatened.
There is a line of applicants for astronaut positions a mile long. The risks are relatively low while the personal ambition and competition for the flight positions is extreme. They know that if they upset the bureaucrats they may never fly. How many of them would risk that opportunity by upsetting an established and massive set of incestuous military, civic, and corporate interests? How would these technologists find an aerospace job after being kicked out of the space program on trumped up bases?
So perhaps the situation is more convoluted than you think it is.
NEWS RELEASE
United States Air Force
Air Force Materiel Command
Office of Public Affairs
Arnold Engineering Development Center
100 Kindel Drive
Arnold AFB, TN 37389-2213
(931) 454-4204
http://www.arnold.af.mil
Writer: Danette Duncan
Date: March 19, 1999
Release # 99-041
Photo # none
AEDC Performs Shuttle Materials Test for NASA/Lockheed Martin
ARNOLD AFB, Tenn.Arnold Engineering Development Center is assisting the National Aeronautics Space Administration with improvements in existing Space Shuttle materials.
According to NASA, during several previous Space Shuttle flights, including the shuttle launched Nov. 29, 1998, the shuttle external tank experienced a significant loss of foam from the intertank. The material lost caused damage to the thermal protection high-temperature tiles on the lower surface of the shuttle orbiter. The loss of external tank foam material and subsequent damage to reentry tiles is a concern because it causes tile replacement costs to significantly increase, however, it is not a flight safety issue. As a result, NASA-Marshall Space Flight Center selected AEDC to perform flight hardware materials tests on the shuttles external tank panels in the centers von Karman Facility Supersonic Tunnel A. The purpose was to establish the cause of failure for the tank thermal protection materials at specified simulated flight conditions. "NASA chose AEDC due to its technical expertise and historical program successes," Steve Holmes, a NASA-MSFC technical coordinator, said.
The Lockheed Martin-manufactured non-reusable external tank, the largest element of the Space Shuttle, fuels the shuttle orbiter during powered flight and is comprised of three componentsa liquid oxygen tank, a liquid hydrogen tank and an intertank assembly that connects the two propellant tanks. At the full capacity of 528,600 gallons of propellant, the external tank weighs 1.6 million pounds. The tank is covered with a multi-layered, spray-on foam insulation that provides thermal insulation for the tank against the extreme internal and external temperatures generated during prelaunch, launch and flight.
Wayne Hawkins, Sverdrup project engineer, explained the foam system is exposed to multiple forces, causing difficulty in determining the actual failure of the thermal protection system. "Multiple forces act on the foam system," Hawkins said. "The environmental factors include thermal protection system cell expansion, aerodynamic loading, highly variable local flow conditions, oscillating shocks, vibration, temperature and main external tank substrate flexure."
Although NASA and other facilities have performed a number of tests in an attempt to define the underlying root cause of this foam loss, they were not successful. At one time, the centers 4-foot and 16-foot transonic aerodynamic wind tunnels were possibilities for the test, but Tunnel As ability to closely duplicate flight conditions and control both ambient pressure and test sample immersion time made it the facility of choice. Tunnel A is a continuous flow-variable density wind tunnel with an automatically driven flexible-plate nozzle and a 40- by 40-inch test section and can cover the Mach number range of 1.5 to 5.5.
"The ideal success for the test is the generation of foam loss on a consistent basis with simulated flight conditions," Hawkins said.
Although the AEDC Tunnel A tests did not replicate the in-flight failures, they did provide detailed measurements to better understand the flight environment and fundamental failure mode. From these tests, NASA determined the failure is caused principally by foam cell expansion due to external heating at approximately Mach 4 combined with pressure change and aerodynamic shear. Specialized miniature shear gages and other instrumentation were installed during the test to measure these forces. The customer and sponsor were pleased with the AEDC test results. "No other facility can test with articles/models as large as AEDC with conditions that can match flight," Holmes said.
FIELD JOURNAL FIELD JOURNAL FIELD JOURNAL FIELD JOURNAL
STS-87 rolled to a stop; the mission was complete! That statement would be true for the flight of the Columbia, however a new mission began when the wheels of the Columbia came to a stop -- the post flight inspections. My division is responsible for the overall analysis of these inspections and we insure that all changes made, due to these inspections, do not affect other areas that may jeopardize the flight-worthiness of the shuttle. This division does not focus on one specific area, but analyzes all information and ensures that all aspects are kept in balance.
Immediately after the Columbia rolled to a stop, the inspection crews began the process of the post flight inspection. As soon as the orbiter was approached, light spots in the tiles were observed indicating that there had been significant damage to the tiles. The tiles do a fantastic job of repelling heat, however they are very fragile and susceptible to impact damage. Damage numbering up to forty tiles is considered normal on each mission due to ice dropping off of the external tank (ET) and plume re-circulation causing this debris to impact with the tiles. But the extent of damage at the conclusion of this mission was not "normal."
The pattern of hits did not follow aerodynamic expectations, and the number, size and severity of hits were abnormal. Three hundred and eight hits were counted during the inspection, one-hundred and thirty two (132) were greater than one inch. Some of the hits measured fifteen (15) inches long with depths measuring up to one and one-half (1 1/2) inches. Considering that the depth of the tile is two (2) inches, a 75% penetration depth had been reached. Over one hundred (100) tiles have been removed from the Columbia because they were irreparable. The inspection revealed the damage, now the "detective process" began.
During the STS-87 mission, there was a change made on the external tank. Because of NASA's goal to use environmentally friendly products, a new method of "foaming" the external tank had been used for this mission and the STS-86 mission. It is suspected that large amounts of foam separated from the external tank and impacted the orbiter. This caused significant damage to the protective tiles of the orbiter. Foam cause damage to a ceramic tile?! That seems unlikely, however when that foam is combined with a flight velocity between speeds of MACH two to MACH four, it becomes a projectile with incredible damage potential. The big question? At what phase of the flight did it happen and what changes need to be made to correct this for future missions? I will explain the entire process.
The questions that needed to be answered were:
At this point, virtually every inch of the orbiter was inspected and all hits were documented and mapped to aid in visualizing the damage. Maps were constructed of the lower surface, the left and right surfaces and the top surface of the orbiter. At this point, a "fault tree" was created. The fault tree provides a systematic approach in considering all possibilities of what may have happened. Everything that is on the fault tree is considered to be legitimate until it is totally ruled out. Some of the considerations were where the damage occurred -- in the OPF, in the VAB, or on the pad before launch. These were quickly eliminated because an inspection at T-3 ("t minus three") hours takes place on each mission and everything was normal.
After these and many other considerations were eliminated, the focus was placed on the ascent, orbit and re-entry phase of the mission. Because of the fore and aft flow characteristics of the damage sites, and the angle of penetration, the ascent phase seemed most likely. The orbit phase of flight was eliminated because the characteristics of these types of hits (most likely meteorites or space debris) occur in a random pattern and direction. Re-entry was eliminated because the "glazing and re-glassifying" of the tiles due to heat upon re-entry (a normal process) indicated that the damage had occurred prior to this phase. The fault-tree was now pointing to the ascent phase.
The pictures that were taken by cameras mounted in the orbiter umbilical began to give the first clues. These cameras are designed to turn on during the solid rocket booster (SRB) separation, and turn off after the separation is complete, thereby recording the event. This process occurs once again when the external tank separates from the orbiter. The initial review of these photographs did not reveal any obvious damage to the external tank. No foam missing, no "divots" (holes) and no material loss. Everything appeared normal.
The SRBs were then focused on for the answers. After inspection of the SRBs, no clues were found. In fact, the solid rocket boosters looked to be in great condition. Where to now? The external tank photographs were magnified and reviewed once again. This time some material loss was noted, but not in a significant degree. The attention was now focused on the crew cabin cameras. These cameras gave more of a side view of the external tank as it tumbled back to Earth. These photographs revealed massive material loss on a side of the external tank that could not be viewed by the umbilical cameras!
Where are we now? One of the questions had now been answered. The ascent phase of flight was when the damage occurred. With the information provided by the photography and the mapped flow of damage, a logical reason could be established as to "what" happened. It was determined that during the ascent, the foam separation from the external tank was carried by the aerodynamic flow and pelted the nose of the orbiter and cascaded aft from that point. Once again, this foam was carried in a relative air-stream between MACH two and MACH 4!
Now the big question -- why? The evidence of this conclusion has now been forwarded to Marshall Space Flight Center (MSFC) because this is the design center for the external tank. MSFC will pursue the cause of damage. Here are some descriptions of some of the considerations:
As this investigation continues, I am very comfortable that the questions will be answered and the solutions applied. In fact, some of the solutions are already in progress. At present the foam on the sides of the tank is being sanded down to the nominal minimum thickness. This removes the outer surface, which is tougher than the foam core, and lessens the amount of foam that can separate and hit the orbiter.
"Environmentally Friendly Foam Kills Seven Astroauts."
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.