NASA’s RCC Leading Edge Tile Repair Plans for Shuttle Fizzle Out
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NASA’s RCC Leading Edge Tile Repair Plans for Shuttle Fizzle Out
NASA’s RCC Leading Edge Tile Repair Plans Fizzle Out
See AW&ST article below. NASA is practicing their blinkered vision again. Read the article carefully and you'll see that they're trying all but the one measure that would afford real protection......and avoid the necessity for repair, rescue and etc (which measure(s) would remain as a last-ditch fall-back position).
Perhaps someone should suggest to them yet again the concept of a sacrificial glove over the vulnerable inboard leading edge RCC panels. Protects RCC tiles during extended on-pad time (against weather and corrosive gantry leaching contaminants), most importantly effectively shields the brittle carbon RCC tiles against impact during launch and burns away early (ablatively and completely) during re-entry interface super-heating. During launch, because of the low Mach numbers attained, it’s non-critical – and doesn't even have to be 100% conformal.
I sent a couple of explicit emails to their publicized email address way back (at www.caib.us) - but received no acknowledgement and I'm betting that they'd not have been read. I did receive an acknowledgement from Dow Corning that they had a suitable silastic material that would fit the bill (about a 1.5" thick coating out to two-thirds span for the wings' and vertical stabilizer's leading edges). That was also forwarded on to NASA (same email address) and to a few Space Industry Journo hacks - but nothing further was heard from them on that either. Search for “sacrificial” on Pprune and you’ll see where the idea came up some 18 months ago. It would appear that NASA isn't interested in avoidance but is fixated on heroic recovery. A Cart before horse mentality methinks.
See AW&ST article below. NASA is practicing their blinkered vision again. Read the article carefully and you'll see that they're trying all but the one measure that would afford real protection......and avoid the necessity for repair, rescue and etc (which measure(s) would remain as a last-ditch fall-back position).
Perhaps someone should suggest to them yet again the concept of a sacrificial glove over the vulnerable inboard leading edge RCC panels. Protects RCC tiles during extended on-pad time (against weather and corrosive gantry leaching contaminants), most importantly effectively shields the brittle carbon RCC tiles against impact during launch and burns away early (ablatively and completely) during re-entry interface super-heating. During launch, because of the low Mach numbers attained, it’s non-critical – and doesn't even have to be 100% conformal.
I sent a couple of explicit emails to their publicized email address way back (at www.caib.us) - but received no acknowledgement and I'm betting that they'd not have been read. I did receive an acknowledgement from Dow Corning that they had a suitable silastic material that would fit the bill (about a 1.5" thick coating out to two-thirds span for the wings' and vertical stabilizer's leading edges). That was also forwarded on to NASA (same email address) and to a few Space Industry Journo hacks - but nothing further was heard from them on that either. Search for “sacrificial” on Pprune and you’ll see where the idea came up some 18 months ago. It would appear that NASA isn't interested in avoidance but is fixated on heroic recovery. A Cart before horse mentality methinks.
NASA Abandons Rigid Overwrap For Patching RCC Holes
By Jefferson Morris
08/11/2004 09:41:02 AM
After encountering "significant technical challenges," NASA is abandoning attempts to develop a rigid overwrap to patch large holes in the space shuttle's reinforced carbon-carbon (RCC) panels in the event of damage during flight, and instead is pursuing other methods that probably won't be ready in time for the shuttle's return to flight, according to agency officials.
The shuttle program plans to fly again in March or April of next year. The Columbia Accident Investigation Board (CAIB) specified that NASA must develop methods of on-orbit thermal protection system (TPS) inspection and repair for the shuttle before that flight. Columbia was lost after foam debris from its external tank punched a large hole in one of the orbiter's RCC leading edge panels.
"The biggest problem with any of the TPS repair techniques [is preserving the] outer mold line," Shuttle Program Manager Bill Parsons said during a teleconference Aug. 3. "The second [problem] is how do we connect something like that to the wing?"
Another problem is the variable geometry of the 22 RCC panels that run along the leading edge of each wing, no two of which are the same. "You'd have to make a wrap that would fit with that geometry, because that outer mold line is so important," Parsons said. "So you end up having to build a number of these panels that would be able to fit in the exact right place on the wing."
Instead, NASA is trying to develop a flexible overwrap with new materials, but this solution will not be ready in time for first flight. Other concepts such as sealing the hole with a ceramic filling also are being considered.
Implementation plan
The latest version of NASA's implementation plan for returning the shuttle to flight was released Aug. 3. For fiscal year 2005, a total of $643 million in return to flight initiatives has been approved or is under review, up from a January estimate of $238 million, according to the plan. Better estimates should be available by the fall, NASA said. The agency expects to spend a total of $465 million on return to flight in FY '04, compared with January's estimate of $265 million.
The shuttle and International Space Station (ISS) programs have completed analysis showing that for at least the first two flights following return to flight, if damage is discovered on a shuttle that prevents it from re-entering, it would be possible to launch a rescue mission within the window of time during which the first shuttle crew can be sustained aboard the ISS (DAILY, Feb. 20).
According to John Casper, deputy of NASA's Return to Flight Planning Team, the shuttle program has "conditionally closed" five of the 15 CAIB recommendations that the agency must implement before returning to flight. The Stafford-Covey Return to Flight Task Group has been charged with assessing whether or not NASA has fulfilled the recommendations.
The five recommendations are:
* Develop and implement a comprehensive inspection plan for all RCC panels, using nondestructive evaluation techniques
* Modify the agreement with the National Geospatial-Intelligence Agency (NGA) to make the imaging of each shuttle while in orbit a standard requirement
* Require that at least two employees attend all final closeouts and inter-tank area hand-spraying procedures
* Kennedy Space Center Quality Assurance and shuttle prime contractor United Space Alliance (USA) must return to the industry-standard definition of "foreign object debris" and eliminate any alternate or statistically deceptive definitions like "processing debris"
* Develop an interim program of closeout photographs for all critical subsystems that differ from engineering drawings, and digitize the system so that images are available immediately for on-orbit troubleshooting.
The shuttle program also has closed out several other CAIB recommendations not specifically related to return to flight, according to Casper, and has made significant progress toward eliminating sources of debris from the external tank. "We have made significant progress also in understanding the ascent debris environment and the material characteristics of the TPS, which includes both the tile and the RCC," he said.
Casper said the shuttle program also is proceeding with a long-term plan for hardening the orbiter against debris impacts, which is the subject of another CAIB recommendation. The first phase of this plan includes measures such as adding insulation to the shuttle's front wing spars, changing the carrier panel bolts for forward RCC panels, eliminating corner voids in the main landing gear doors and adding stronger orbiter windows.
By Jefferson Morris
08/11/2004 09:41:02 AM
After encountering "significant technical challenges," NASA is abandoning attempts to develop a rigid overwrap to patch large holes in the space shuttle's reinforced carbon-carbon (RCC) panels in the event of damage during flight, and instead is pursuing other methods that probably won't be ready in time for the shuttle's return to flight, according to agency officials.
The shuttle program plans to fly again in March or April of next year. The Columbia Accident Investigation Board (CAIB) specified that NASA must develop methods of on-orbit thermal protection system (TPS) inspection and repair for the shuttle before that flight. Columbia was lost after foam debris from its external tank punched a large hole in one of the orbiter's RCC leading edge panels.
"The biggest problem with any of the TPS repair techniques [is preserving the] outer mold line," Shuttle Program Manager Bill Parsons said during a teleconference Aug. 3. "The second [problem] is how do we connect something like that to the wing?"
Another problem is the variable geometry of the 22 RCC panels that run along the leading edge of each wing, no two of which are the same. "You'd have to make a wrap that would fit with that geometry, because that outer mold line is so important," Parsons said. "So you end up having to build a number of these panels that would be able to fit in the exact right place on the wing."
Instead, NASA is trying to develop a flexible overwrap with new materials, but this solution will not be ready in time for first flight. Other concepts such as sealing the hole with a ceramic filling also are being considered.
Implementation plan
The latest version of NASA's implementation plan for returning the shuttle to flight was released Aug. 3. For fiscal year 2005, a total of $643 million in return to flight initiatives has been approved or is under review, up from a January estimate of $238 million, according to the plan. Better estimates should be available by the fall, NASA said. The agency expects to spend a total of $465 million on return to flight in FY '04, compared with January's estimate of $265 million.
The shuttle and International Space Station (ISS) programs have completed analysis showing that for at least the first two flights following return to flight, if damage is discovered on a shuttle that prevents it from re-entering, it would be possible to launch a rescue mission within the window of time during which the first shuttle crew can be sustained aboard the ISS (DAILY, Feb. 20).
According to John Casper, deputy of NASA's Return to Flight Planning Team, the shuttle program has "conditionally closed" five of the 15 CAIB recommendations that the agency must implement before returning to flight. The Stafford-Covey Return to Flight Task Group has been charged with assessing whether or not NASA has fulfilled the recommendations.
The five recommendations are:
* Develop and implement a comprehensive inspection plan for all RCC panels, using nondestructive evaluation techniques
* Modify the agreement with the National Geospatial-Intelligence Agency (NGA) to make the imaging of each shuttle while in orbit a standard requirement
* Require that at least two employees attend all final closeouts and inter-tank area hand-spraying procedures
* Kennedy Space Center Quality Assurance and shuttle prime contractor United Space Alliance (USA) must return to the industry-standard definition of "foreign object debris" and eliminate any alternate or statistically deceptive definitions like "processing debris"
* Develop an interim program of closeout photographs for all critical subsystems that differ from engineering drawings, and digitize the system so that images are available immediately for on-orbit troubleshooting.
The shuttle program also has closed out several other CAIB recommendations not specifically related to return to flight, according to Casper, and has made significant progress toward eliminating sources of debris from the external tank. "We have made significant progress also in understanding the ascent debris environment and the material characteristics of the TPS, which includes both the tile and the RCC," he said.
Casper said the shuttle program also is proceeding with a long-term plan for hardening the orbiter against debris impacts, which is the subject of another CAIB recommendation. The first phase of this plan includes measures such as adding insulation to the shuttle's front wing spars, changing the carrier panel bolts for forward RCC panels, eliminating corner voids in the main landing gear doors and adding stronger orbiter windows.
Still no fix for US Space Shuttle
Fri 27 August, 2004 05:34
By Broward Liston
CAPE CANAVERAL, Florida (Reuters) - One year after a highly critical report urged NASA to develop the means to fix a broken space shuttle in orbit, the U.S. space agency still could not repair a hole the size of the one that doomed the seven Columbia astronauts. A piece of foam that broke off Columbia's external fuel tank 81 seconds after lift-off left a gash in the left wing and caused the 100-tonne ship to break up as it re-entered the atmosphere in February 2003.
Since then, NASA has experimented with various patches but has found none that could resist the 3,000 degree F (1650 degrees C) temperature of re-entry, said Bill Parsons, the shuttle program manager, who spoke to reporters on Thursday on the anniversary of the Columbia Accident Investigation Board's report.
"We've made a lot of progress, but we've not been able to come up with an over-wrap in this time frame that would allow us to fix a large hole," said Parsons. "Our expectation is that we'll fix the tank and there won't be anything like that we'll have to deal with."
This month, officials at the New Orleans plant where Lockheed Martin Corp assembles the $40 million (22 million pound) fuel tanks said they were certain the same accident would not occur again because they would, on future missions, remove the 1.5-pound (0.68 kg) piece of foam that broke away during Columbia's ascent. But these officials made clear that they had not yet met the exacting standards set by the accident board that require nothing heavier than a fraction of an ounce of foam to come off the tank after lift-off.
Most shuttle flights, since the program started in 1981, have resulted in at least some foam breaking off. The fuel tank for the return-to-flight mission in 2005 is due to be sent from New Orleans to the Kennedy Space Centre launch facility in Florida in early November. Despite the obstacles, NASA officials said they remain upbeat that the shuttle Discovery will make a launch window next year that runs from March 16 to April 18.
The accident investigation report released last year excoriated the agency for a number of failings, including an operating culture that suppressed dissent. Thomas Krause, president of Behavioural Science Technology, a consultant brought in by NASA to help transform that culture, said there was ample evidence that employees were no longer afraid to speak up about safety and engineering issues.
But he acknowledged that there was "no clear cut answer" to determining what is acceptable risk.
Once the shuttles are flying again, NASA hopes to keep an ambitious schedule averaging five flights a year until construction of the International Space Station is complete and the shuttle fleet is retired in 2010, but that date could slip if the launch schedule does.
"The milestone is the completion of the International Space Station, not the end of the decade," said Bill Readdy, NASA's associate administrator for the shuttle and space station programs.
The moon and Mars initiative announced by President George W. Bush in January will not begin flying until funding for the shuttle and space station can be shifted to it.
Fri 27 August, 2004 05:34
By Broward Liston
CAPE CANAVERAL, Florida (Reuters) - One year after a highly critical report urged NASA to develop the means to fix a broken space shuttle in orbit, the U.S. space agency still could not repair a hole the size of the one that doomed the seven Columbia astronauts. A piece of foam that broke off Columbia's external fuel tank 81 seconds after lift-off left a gash in the left wing and caused the 100-tonne ship to break up as it re-entered the atmosphere in February 2003.
Since then, NASA has experimented with various patches but has found none that could resist the 3,000 degree F (1650 degrees C) temperature of re-entry, said Bill Parsons, the shuttle program manager, who spoke to reporters on Thursday on the anniversary of the Columbia Accident Investigation Board's report.
"We've made a lot of progress, but we've not been able to come up with an over-wrap in this time frame that would allow us to fix a large hole," said Parsons. "Our expectation is that we'll fix the tank and there won't be anything like that we'll have to deal with."
This month, officials at the New Orleans plant where Lockheed Martin Corp assembles the $40 million (22 million pound) fuel tanks said they were certain the same accident would not occur again because they would, on future missions, remove the 1.5-pound (0.68 kg) piece of foam that broke away during Columbia's ascent. But these officials made clear that they had not yet met the exacting standards set by the accident board that require nothing heavier than a fraction of an ounce of foam to come off the tank after lift-off.
Most shuttle flights, since the program started in 1981, have resulted in at least some foam breaking off. The fuel tank for the return-to-flight mission in 2005 is due to be sent from New Orleans to the Kennedy Space Centre launch facility in Florida in early November. Despite the obstacles, NASA officials said they remain upbeat that the shuttle Discovery will make a launch window next year that runs from March 16 to April 18.
The accident investigation report released last year excoriated the agency for a number of failings, including an operating culture that suppressed dissent. Thomas Krause, president of Behavioural Science Technology, a consultant brought in by NASA to help transform that culture, said there was ample evidence that employees were no longer afraid to speak up about safety and engineering issues.
But he acknowledged that there was "no clear cut answer" to determining what is acceptable risk.
Once the shuttles are flying again, NASA hopes to keep an ambitious schedule averaging five flights a year until construction of the International Space Station is complete and the shuttle fleet is retired in 2010, but that date could slip if the launch schedule does.
"The milestone is the completion of the International Space Station, not the end of the decade," said Bill Readdy, NASA's associate administrator for the shuttle and space station programs.
The moon and Mars initiative announced by President George W. Bush in January will not begin flying until funding for the shuttle and space station can be shifted to it.
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This was also a case of envirnmentalism and political correctness run amok.
The covering on the fuel tank (insulation) had been changed somewhat in the face of toughening envirnmental standards (not actually required to be adhered to btw) Immediately it was noted that the size and numbers of impacts on the shuttles had gone up dramatically, but instead of switching back to the better insulation Nasa just chose to ignore it.
I find that horrifying.
Cheers
Wino
The covering on the fuel tank (insulation) had been changed somewhat in the face of toughening envirnmental standards (not actually required to be adhered to btw) Immediately it was noted that the size and numbers of impacts on the shuttles had gone up dramatically, but instead of switching back to the better insulation Nasa just chose to ignore it.
I find that horrifying.
Cheers
Wino
I find that horrifying.
It's easy to say now and I don't wish to criticise the Columbia crew but the fact that they received notice of the foam strike should have started some major alarm bells ringing, in my opinion. Despite what anyone says....space travel is still very much a hazardous passtime and should not be thought of as 'operational'. Safety must come first. Hopefully Nasa will refocus on safety in the future and not get too carried away again.
0918
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In the case of the the columbia crew even had the wing been completely missing and they looked out and saw it that way there was absolutely NOTHING that could have been done for them.
Nasa could not have launched another shuttle before they ran out of oxygen, they could not have altered their orbit to reach the space station (Orbital mechanics dictated there wasn't nearly enough fuel on the columbia to make such a radical shift)
So there was nothing the astronauts could do except start the re entry and hope for the best, which is precisely what they did. What else could they do?
Cheers
Wino
Nasa could not have launched another shuttle before they ran out of oxygen, they could not have altered their orbit to reach the space station (Orbital mechanics dictated there wasn't nearly enough fuel on the columbia to make such a radical shift)
So there was nothing the astronauts could do except start the re entry and hope for the best, which is precisely what they did. What else could they do?
Cheers
Wino
You're right of course and I appreciate that knowledge of the damage was useless to the crew. I was more concerned by the apparent disinterest of the crew when notified. This is, however, just my opinion. I accept that the crew may well have suspected a major risk with the re-entry and that this information would only have been fully appreciated by them.
0918
0918
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Someone needs to come up with some "Space Bondo" or the risk to the crews is of grave concern. How can you continue to operate any vehicle with this kind of known defect? I wonder what Dr. Feynman would have to say about this current dilemma. He had a great way of cutting through the bureaucracy and solving problems.
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I did receive an acknowledgement from Dow Corning that they had a suitable silastic material that would fit the bill (about a 1.5" thick coating out to two-thirds span for the wings' and vertical stabilizer's leading edges).
I'm guessing that by "Space Bondo" you mean something that the Shuttle crew can utilize in orbit to reliably patch a hole the size of the one that destroyed Columbia. If so, that's what they have now given up on at NASA/USA. However they are getting the cart before the horse anyway (IMHO). The objective should be to protect the brittle RCC leading edges from damage whilst on the launch-pad (for months in the case of Columbia's STS107) - and on launch against foam and bolts and other fast-moving detritus.
That concept has always been called "the SACRIFICIAL GLOVE" and Dow Corning experts have already said that they have just the stuff.
Requirement? A silastic compound that will stay in place and protect the RCC leading edges from blunt-force trauma until the craft is in orbit - but one that will easily burn away uniformly under the searing heat of re-entry without leaving any notable residue. The substance exists and is already in use in the nuclear fuels industry. However getting NASA (or Boeing Contractor - the United Space Alliance) to listen post-Columbia tragedy is just as hard as getting them to listen before.
Bottom line is that they haven't discarded that SACRIFICIAL GLOVE concept - they are simply unaware of it. Why is that? Because they neither look, listen nor learn - and certainly cannot hear.
OT
