An Important Observation

updated 14 Feb 03

PickyPerkins said:

The picture of Columbia at a mere 40 miles-up is unimpressive. It was released to the press as a negative and, either way, is inconclusive but significant. It just appears to show an anomaly on the left wing leading-edge where RCC sections should be. It also shows a more pronounced trail from the left wing immediately aft of that anomaly. It is of course presently a coincidence that drag was observed to be building up on that side at the time. I think I see something projecting forward of the leading edge of the left wing in the flipped image. What do other people see?

PickyPerkins also said:

DrSyn posted a photo which has been said (not by DrSyn) to show a “bite out of the wing”.

I may be trying to squeeze more out of this fuzzy photo than there is to be squeezed, but my impression is that it shows something projecting forward of the wing rather than something bitten out of it.

To make this easier to talk about, I took the image of the left-hand side of the a/c and flipped top-to-bottom, and drew in some vertical guide lines. I accept that the photo does not show a truly plan view. However, I think it's near enough.

I think I see something projecting forward of the leading edge of the left wing in the flipped image. What do other people see?

The lower images are copies of the first two, but with more contrast.

What could the projection be (if it is really there at all)? Is it a solid part of the Orbiter? I assume not, but it might be. Could it be material being ablated off the wing? The atmosphere was very thin where it was photographed over New Mexico, at maybe 200,000 ft. Could ablated material move up-wind at all on a vehicle moving at more than Mach 20 in a VERY thin atmosphere? I have no idea.

Anybody have any relevant information or opinions?

In order to answer this, I'll first comment (in green) upon the extracts below by highlighting the important areas.

But first you should look at the diagrams and photos here
The AW&ST Article suggesting a "Leading Edge" Event
The Pre-Crash Daugherty Email (2mb pdf file)

All the above is  from this link on Pprune

STS-107 SECOND DAILY REPORT …….. At approximately 81 seconds mission elapsed time (MET), a large light-colored piece of debris was seen to originate from an area near the ET/Orbiter forward attach bipod. 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 strike appears to have occurred on or relatively close to the wing glove near the Orbiter fuselage. After striking the left wing the debris broke into a spray of white-colored particles that fell aft along the underside of the Orbiter left wing. ……….. -------- End quote --------- However, in all the news conferences, the debris was said to have struck the underside of the wing.

This appears to be a clarification that the debris struck the leading edge.

KENNEDY SPACE CENTER, Florida (CNN) -- Photographs taken by an Air Force tracking camera shortly before the space shuttle Columbia disintegrated show serious structural damage to the shuttle's .left wing, an aviation magazine reported Friday. The images, captured about a minute before the shuttle broke apart, show a jagged edge on the left wing structure near where the wing begins to intersect with the fuselage, according to a report in Aviation Week & Space Technology. Columbia's right wing and fuselage appear normal in the photos, the magazine said. The damage to the left wing indicates either a small structural breach, such as a crack, or that a small piece of the wing's leading edge fell off, according to the magazine. It said NASA investigators at Johnson Space Center in Houston, Texas, are analyzing the pictures Another key factor is that the leading edge of the shuttle wing, where the jagged shape was photographed, transitions from black thermal protection tiles to a much different mechanical system made of reinforced carbon-carbon material that is bolted on, rather than glued on as the tiles are. This means that in addition to the possible failure of black tile at the point where the wing joins the fuselage, a failure involving the attachment mechanisms for the leading edge sections could also be a factor, either related or not to the debris impact. The actual front structure of a shuttle wing is flat. To provide aerodynamic shape and heat protection, each wing is fitted with 22 U-shaped reinforced carbon-carbon (RCC) leading-edge structures. The carbon material in the leading edge, as well as the orbiter nose-cap, is designed to protect the shuttle from temperatures above 2,300F during re-entry. Any breach of this leading-edge material would have catastrophic consequences.

The "U-shaped" would be clearer if they'd said "D-shaped" (i.e. with the upright of the D being "the actual front structure of the shuttle wing that is flat". Obviously exposing this flat to the airflow would be catastrophic. However, this further NASA statement below seems to dismiss this as being at all likely:

The third and final summary issued on Jan. 27 discusses the black tiles again, but also specifically says "Damage to the RCC [wing leading edge] should be limited to [its] coating only and have no mission impact."

I am not at all sure that a bolted on carbon-carbon structure would have much structural integrity at all once subjected to an impact of a sharp-edged (ice-heavy) 3lb piece of ET foam moving at speed. All references to the RCC substance refer to it as being very hardened (but I would assume that that "hardening" is against heat - and that it is brittle in respect of any significant sharp-edged (or pointy) impact ). It is possible that the post-impact debris cloud seen was only the iced foam but is it possible that the RCC "D" section at the point of impact could have been shattered? If so, without its structural integrity, how would it stand up to extreme heating? Indeed, once cracked, would that "bolted" RCC D Section have ANY structural integrity for RETENTION - at all????

The sequence of sensor measurements and failures is puzzling, particularly one reading — in a part of the mid-fuselage not connected to any of the wire bundles linked to the other sensors that were going haywire. “Whether that’s important or not, we don’t know,” Dittemore said. Though the sensor data are being closely examined, it’s possible the source of heat might not have been near them.

The cheap and very easy explanation here is that the remote heating was conductively being caused by a solid metallic connection to an intense source of localised heating (such as along a L.E. spar member or other wing major structural (to in-fuselage) element - i.e. NOT along a wire-bundle or via super-heated air-flows). So for this sort of heating to have taken place, there must have been an ongoing major source of intense heat. The question then becomes: "What/where might this have been?"


So we have:

a.  Picky's question (and diagram) about something appearing to be projecting forward of the leading edge

b.  An ET foam debris strike that may well have been on the leading-edge (and not under the wing , i.e. not in vicinity of the wheel-well door)

c.  A photo taken 60 secs before break-up showing (according to A.W.&S.T.) a jagged LHS inboard L.E.

d.  Seemingly inexplicable heating of a quite remote in-fuselage area.

e.  The jagged "projection" is located at the RCC/black-tile transition point on the wing fillet (glove) (RCC carbon-carbon is very hard, best heat resister and is bolted on). Behind the RCC sections, the wing structure is a flat.

f.   A break-up that obviously started (from a Californian Astronomer's observations) from about the re-entry point. Inference here is that the eventual break-up was a function of an ongoing intense heat-soak ablative degradation of a pre-reentry damaged area of the inboard left L.E.

g.  As disclosed by the USAF photo, a LHS inboard trailing plume that has been variously interpreted as an RCS firing, a smoke-trail or a shedding of ablated material.

h.  The information that Columbia (with its ET) had sat on a cold, rain-soaked launch pad for longer than any other Shuttle (before being launched). I think I saw a figure of 39 days.

i.  From this link (The Pate-Cornell/Fishbeck 1994 Paper of "Risk Management for theTiles of the Space Shuttle") the harsh fact that once tile surface integrity is lost (by as little as one tile in a critical area), the ongoing surrounding loss is like a cancer spreading. The wing leading edge is one such critical area. We are also told that Columbia (as the first Orbiter) had a history of early tile problems.

j.  The telemetry-recorded progression of heat-sourced sensor failures (i.e. of wiring bundles) and heat-related damage (shown elsewhere)

k.  The eventual telemetry-end evidence that the "growing" left wing problem had finally run the Orbiter out of lateral controllability.


Looking at point j. first, wire-bundles can be interdicted anywhere along their length so their point of failure is hard to pin down. By comparison. if the remote area of in-fuselage heating was associated with a metallic structure directly connected to the left inboard Leading Edge's front-spar (highly likely) then that was most probably due to heat conducted from a long-term intense heat-source at the leading edge point of failure ( i.e. a bit of a smoking gun here). But why would that area heat up so intensely?

If the ET foam had sat out there in the rain cold-soaking and soaking up moisture for 39 days (TBC), it's not surprising that there should later be foam debris on launch (once the ET was fuel-filled and that water-soaked foam became ice). If that foam was heavier (because iced) and pointedly hit the RCC junction and that RCC section shattered, then its being only "bolted on" would be its downfall -  it would have later separated quite early under the airflow and heat stresses of re-entry. You would then have a flat surface (albeit on an obliquely-swept wing planform) being presented as a flat plate (initially over a short section) to a hypersonic flow. I myself cannot recall any aerodynamic lessons that ever investigated flat-plate hypersonic shock-waves - but the heat energy generated at that point would be extremely intense. It would be a bubble of heat plasma extending hemispherically forward of the wing's Leading Edge. The localized intense heat build-up would weaken the wing's structure locally, and in particular any transiting wiring bundles - but two other areas would also suffer heat effects:

a.  the immediate (and then the more distant) surroundings such as the wheel-well (where the sensors happened to be for pick-up of temperatures for various sub-systems) plus

b.  the sensor for any distant (remote) (in-fuselage) area connected to that tile-failure point via a substantial piece of heat-conducting metal (such as a spar-connect to a fuselage sub-frame).


How would that radially-radiating flat-plate shockwave and its intense highly-localized thermal source look to the USAF camera? Opaquely like a jagged projection (bubble) forward of the wing leading-edge? I think so.

And what was the plume behind? Ablated RCC carbon-shredding as the heat, shocks and airflow eroded outboard along the L.E., heating it up.

Picky said (10 Feb) "Note added 10th Feb. 2003
Looking at the video shot in Texas it seems obvious that ablated or burning material can and does move ahead of the solid material. So personally I now tend to believe the photo may show ablating material both ahead of and trailing behind the left wing.

I don't think so. I do NOT think (either) that it was anything to do with a "not quite overhead shot" or a banked attitude. In fact the damage discussed above may have propagated ALONG the LH leading edge by the time this shot was taken (60 secs prior to break-up).... and explain that loss of definition along that LH leading edge as a combination of heat blur and erosion of tiles.



 Rather than a tile having been lost, it’s becoming apparent that a section of the “bolted” on RCC (reinforced carbon-carbon) leading edge was hit and shattered (and was then crumbled away by the hypersonic flow). There are a number of mutually confirming reasons for believing that this may have been the case. They’re set out below and in the links.

  1. The RCC leading-edge structures are bolted to the wing using Inconel fittings that attach to aluminum flanges on the front of the wing. Hard to believe that “bolted on” reinforced carbon-carbon would retain any structural (or retentive) integrity  under the blow from a large iced piece of tank foam moving with considerable momentum at lift-off plus 81 secs – particularly if it hit pointedly. It is not the "toughened" leading edge that it is being represented as - leastwise not as far as impacts are concerned. The Columbia sat on a cold rain-soaked pad longer than any other shuttle before it (i.e. 39 days) and in the coldest Florida weather spell for about 50 years. The tank foam would have soaked up much moisture. It would appear that its adhesive wasn’t impervious to moisture (or possibly that freeze/melt/freeze cycles are capable of cracking that foam).
  2. From the pink-tinged diagram at link two, by reference to the leading-edge photo below and from the foam debris impact videos you can get a good idea of just where that impact probably occurred. If the RCC section in that area was only shattered (and not removed), its pieces would quickly lose their “bolted on” integrity and start to separate. Behind those sections you have an oblique flat-plate presenting to the hypersonic airflow.
  3. The “jagged leading edge” (LE.) damage depicted on the USAF photo is actually a camera-opaque superheated plasma bubble projecting ahead of the leading edge – originating around the damaged RCC section. It’s important to note that early on in the space program NACA (NASA’s predecessor) became convinced of the advantages of a blunt leading edge allowing re-entry heat dissipation in the bow-wave ahead (instead of fixed and jettisonable beryllium shields). Think of that flat-plate behind the damaged RCC section as being a very blunt section.
  4. You can easily see the proximity to the wheel-well that has now been admitted (by NASA engineers) to have been breached (and heated by super-heated plasma). The initial boundary conditions of intact RCC sections either side of the L.E. breach would have caused that highly localized plasma bubble (which is probably what is shown as a projection ahead of the Left wing in the USAF photo –taken 60 secs before the break-up). Once subjected to the super-heated plasma, the underlying aluminium could have been easily penetrated.
  5. From that same pink-tinged diagram you can see the orange lines representing the wiring bundle lines to the sensors that first “dropped out” - and note their immediate proximity to the suggested area of RCC damage.
  6. If you scan that (overlaid USAF photo) diagram, you can see that the photographed dense trailing stream of “ablated” material is more outboard than the “more inboard” postulated RCC section damage position. That’s due to a characteristic of the sheet vortex associated with a delta planform at high AoA (called spanwise blowing) – and possibly also indicates that the more outboard sections of RCC were being “peeled” off the swept L.E. by the airflow. Once an RCC section was compromised, the tiles behind (top and bottom surface) would also present a lip to the hypersonic airflow. Shock-waves would form at (and work on) these protuberances. This progressive L.E. and surface degradation would also explain why it took about 15 minutes for the elevons and RCS (Reaction Control System) to run out of lateral controllability.
  7. Currently NASA engineers are claiming that the main-wheel tyres would not have burst inside the wheel-well. They are rated at 340psi max at a nominal 75degF. The recovered tyre photo below is showing signs of an overpressure burst (an across-casing split).  The ultimate event (post-telemetry cut-off) may have been due to heat-detonation of the gear's blow-down explosive squibs.

Once the Shuttle’s Thermal Protection System (TPS) loses its integrity at a critical point, it is like a house of cards. As I see it at this point two measures may have avoided this accident:

  1. A “re-entry sacrificial” layer of rubberized/vulcanized leading edge tape may have been sufficient to protect the Orbiter’s most impact-vulnerable sections (the bolted on carbon-carbon RCC) from ET iced foam debris hits (shatter-blows) on launch.


  1. A policy of NOT leaving a mated launch-ready Shuttle on the pad exposed to the elements for lengthy periods may have avoided the foam-shedding (which was a well-known, but dismissed, phenomena).


As crew escape during re-entry isn’t a viable proposition NASA needs to evolve a protective repair that can be applied in a standard pre-reentry EVA. They also need a remote-controlled camera that can inspect all the critical areas before re-entry, Imagery being sent back to Mission Control for confirmation of the necessity for an interim repair. NASA has previously called in orbit repairs impractical. It's a proposition that deserves another look.

The two URLS below are mutually supportive (Link one has the graphics)
Link ONE
Link TWO - i.e. this page

Email warned of 'catastrophic' failure

The Associated Press
Posted February 12, 2003, 2:21 PM EST

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WASHINGTON -- A NASA engineer weighed the possibility of a "catastrophic" failure resulting from extreme heat on the shuttle Columbia's tires despite assurances days earlier that possible damage to insulating tiles near the landing gear wouldn't imperil the crew.

In internal e-mails released by NASA on Wednesday, one safety engineer, Robert H. Daugherty, warned that extreme temperatures during a fiery descent could cause the wheel to fail and the tire to burst inside Columbia's wheel well.

"It seems to me that with that much carnage in the wheel well, something could get screwed up enough to prevent deployment and then you are in a world of hurt," Daugherty wrote to officials at Johnson Space Center. He added that such an internal blast "would almost certainly blow the door off the hinges or at least send it out into the slip stream -- catastrophic."

Daugherty acknowledged his concerns were "over the top in many ways," but added that, "this is a pretty bad time to get surprised and have to make decisions in the last 20 minutes."

He cautioned in his e-mail, "I am admittedly erring way on the side of absolute worst-case scenarios, and I don't really believe things are as bad as I'm getting ready to make them out."

Since Columbia's breakup over Texas, senior NASA officials have expressed repeated confidence in conclusions by engineers at The Boeing Co., its contractor, that the shuttle could return safely despite the risks of damage to delicate thermal tiles on its left wing that might have occurred on liftoff.

In prepared testimony for a congressional hearing Wednesday, NASA Administrator Sean O'Keefe wrote to lawmakers that during the 16-day mission, "we had no indications that would suggest a compromise to flight safety."

An internal assessment by Boeing experts on Jan. 23 -- seven days after liftoff -- predicted "safe return indicated," even if the foam insulation that fell from Columbia's external fuel tank had caused "significant tile damage."

But NASA confirms that officials from the Space Center called experts Jan. 27 -- four days later -- at its Langley research facility in Hampton, Va., to ask what might happen if the shuttle's tires were not inflated when it attempted to land.

Daugherty's e-mail, sent Jan. 30 in response to the telephone inquiry, considered the risks that an explosion in Columbia's wheel well from overheating could damage other important systems inside, prevent one side's landing gear from lowering, require a risky belly-landing or force the crew to bail out.

A bailout would be "not a good day," Daugherty wrote. But attempting to fly the shuttle with only one side's gear lowered would be worse: "You're finished."

A Boeing executive said on Tuesday that these kinds of follow-up discussions weren't unusual.

"Many times we generate a report and it generates a question somebody else notices," said Michael I. Mott, Boeing's vice president and general manager of NASA systems. "These are ongoing things, and we never give up and declare victory and move on. They are continuously reviewed to make sure we haven't missed something."

NASA spokesman Keith Henry said an engineer from Langley responded that excessive heating due to failure of the shuttle's thermal protection system could cause damage to Columbia's wheel and tire, which could prevent pilots from lowering the gear at landing.

Officials at Johnson acknowledged that was an important concern, Henry said.

Such an inquiry for Langley researchers involving the safety of a shuttle's tires was unprecedented, Henry said Tuesday. He said that NASA, in its questions, did not specify which tires it was worried about.

Among the earliest warning signs aboard Columbia in the minutes before its destruction was an unusual heat buildup of about 30 degrees inside the left wheel well. Investigators have said they are confident the tire inside didn't deflate, but they have been unable to explain the mysterious readings.

Boeing's study assumed the foam debris struck part of Columbia's left wing, including its toughened leading edge and thermal tiles covering the landing gear. It concluded the shuttle would have a "safe return capability," although it cautioned about some of the assumptions engineers used in their predictions.

One expert wrote that Columbia's "flight condition is significantly outside of test database," because engineers were relying on scientific models involving impacts from chunks of foam 3 cubic inches in size. Officials believe the foam that struck Columbia was 1,920 cubic inches.

NASA officials have defended the analysis.

"I am convinced that what we looked at in real time, discussions that went on, were painstakingly dealt with," said Milt Heflin, chief of the flight director's office. "I have sat through many discussions on nuts and bolts and washers to great excruciating detail, and there's absolutely no reason for me to believe that this was shortchanged at all."

Shuttle program manager Ron Dittemore said last week that safety conclusions were presented to Columbia's commander, Rick Husband, and that he "was perfectly satisfied with the explanation."

Mott said Boeing recognizes that its engineering analysis will be "scrubbed six ways to Sunday" by investigators trying to determine why Columbia disintegrated as it returned from its 16-day mission.

"There was a very rigorous process applied involving some of the top technical talent on this planet," Mott said. "We thought we were going to bring Columbia safely home. We believed that then, we believe that now. We think that analysis was right on."


: Shuttle's Skin Breached

By TED BRIDIS | Associated Press Writer
Posted February 13, 2003, 7:47 PM EST

WASHINGTON -- The space shuttle Columbia almost certainly suffered a devastating breach of its skin, allowing superheated air inside the left wing and possibly the wheel compartment during its fiery descent, investigators said Thursday.

In its first significant determination, the accident investigation board announced that heat damage from a missing tile would not be sufficient to cause the unusual temperature increases detected inside Columbia minutes before it disintegrated. Sensors noticed an unusual heat buildup of about 30 degrees inside the wheel well before the accident.

Instead, the board determined those increases were caused by the presence inside Columbia of plasma, or superheated air with temperatures of roughly 2,000 degrees. It said investigators were studying where a breach might have occurred to allow plasma to seep inside the wheel compartment or elsewhere in Columbia's left wing.

The board did not specify whether such a breach could be the result of a structural tear in Columbia's aluminum frame or a hole from debris striking the spacecraft. The board also did not indicate when the breach occurred during the shuttle's 16-day mission.

Officials have previously focused on an unusually large chunk of foam that broke off Columbia's external fuel tank on liftoff. Video footage showed it struck part of the shuttle's left wing, including its toughened leading edge and the thermal tiles covering the landing gear.

The announcement focused renewed attention on possible catastrophic failures inside the wheel compartment that may have contributed to the Feb. 1 breakup that killed seven astronauts.

Officials are not sure where a breach might have opened in Columbia's skin, NASA spokesman James Hartsfield said. But he said the leading edge or elsewhere on the left wing, the fuselage or the left landing gear door were prime candidates.

"Any of those could be potential causes for the temperature change we saw," Hartsfield said. "They do not and have not pinpointed any general location as to where that plasma flow would have to originate."

In an unusual plea for assistance, NASA urged Americans on Thursday to share with them any photographs or videotapes of Columbia's descent from California to eastern Texas. Some members of the public have already handed over images, "but more material will help the investigation of the Columbia accident," the agency said.

The board's announcement didn't surprise those experts who have long believed that a mysterious failure of sensors within Columbia's left wing indicated that super-hot plasma had penetrated the shuttle.

"I think there was a substantial hole in the wing," said Steven P. Schneider, an associate professor at Purdue University's Aerospace Sciences Laboratory. "That would not be at all surprising. All the sensors in the wing failed or gave bad readings" by the time ground controllers lost contact with Columbia, he said.

The board dismissed suggestions Columbia's left landing gear was improperly lowered as it raced through Earth's atmosphere at more than 12,000 miles per hour. NASA disclosed earlier Thursday that a sensor indicated the gear was down just 26 seconds before Columbia's destruction.

If Columbia's gear was lowered at that speed -- and in those searing temperatures as the shuttle descended over Texas from about 40 miles up -- the heat and rushing air would have sheared off Columbia's tires and led quickly to the spacecraft's tumbling destruction, experts said.

Officials said they were confident that unusual sensor reading was wrong. Tires are supposed to remain raised until the shuttle is about 200 feet over the runway and flying 345 miles per hour.

Two other sensors in the same wheel compartment indicated the gear was still properly raised, they said.

While Columbia's piloting computers began almost simultaneously firing thrusters struggling to keep wings level, officials said, a mysterious disruption in the air flowing near the left wing was not serious enough to suggest the shuttle's gear might be down.

The investigating board concluded that its research "does not support the scenario of an early deployment of the left gear."

Click on image for enlarged hi-res version

NASA also confirmed that searchers near Hemphill, Texas, about 140 miles northeast of Houston, recovered what is believed to be one of Columbia's radial tires. A spokesman was not immediately sure which of the shuttle's tires was found.

The tire was blackened and sustained a massive split across its tread, but it was impossible to know whether the tire was damaged aboard Columbia or when it struck the ground.

The board's announcement came one day after NASA released e-mails showing midlevel safety engineers in Virginia and Houston considered the risks of tires bursting inside Columbia's belly from heat damage.

Robert H. Daugherty, responding to an inquiry from Johnson Space Center, cautioned in one of those e-mails that damage to insulating tiles near the landing gear door could cause one or more tires inside to rupture, perhaps ending with "catastrophic" failures that would place the seven astronauts "in a world of hurt."

Ret. Adm. Harold Gehman, who heads the panel investigating the Columbia accident, called Daugherty's concerns "one of the many, many interesting leads that we have."

from this link