From NASA engineering film: Sequential pix of debris hitting Columbia's wing

NASA via CNN Online & Yahoo News ^ | 2/3/03 | Wolfstar

[Wolfstar]

Released Monday morning, a high-speed NASA engineering film shows a piece of debris falling from the large external tank on the space shuttle Columbia's liftoff and hitting the orbiter's left wing. Bear in mind that these are extreme close-ups of a high-speed event. In the top couple of photos, you see only the top of the broken-off piece. Most of it is in the shadows. Depending on which clip you see and how slowly it is run, to the uninitiated person's eye, it can look either like the debris strikes the wing hard enough to pulverize the debris, or the debris strikes a glancing blow and bounces off in the direction of the main and booster engine exhaust.

[sd-joe]

"Have they recovered the black Box yet?
Doesn't have one???
Why not???"

They stated that they had a tape voice recorder but it would not have survived. They probably do not have much on-board data recording, because everything is being transmitted to the ground constantly. The only time it is not, is the few minutes of comm loss during the very high heat part of re-entry.

[Howlin]

It's getting on my nerves, how about you? It's kind of scary, too! :-)

[El Gato]

NASA has already comfirmed it was insulation from the fuel tank.

Do you know how they confirmed it? I guess it could be from pictures of the tank separation from the orbiter, which they film from on board the shuttle. Presumably you could ID the spot with the missing insulation.

Now does anyone know how dense that insulation is, and if it's brittle or more flexible? Like I stated above, I'm beginning to think this "Tile damage during the ascent" is a dead end, and not the cause of the breakup on reentry. What that cause might be, I don't really know.

[Jael]

Actually, NASA concluded that there was not enough damage to worry about and even if there was, as Dittemore says, there was nothing they could do about it.

My problem is they knew about the foam breaking off and striking the Shuttle since 1997.

I don't think they could have known (in real time) the extent of the damage. And if they would of known, I believe that they would of ordered an abort. I don't think for one minute that they would send their comrades to a certain death.

I do think NASA grew complacent about the freon-less foam. And since this was the heaviest shuttle ever, it was a bad time to try and save on the ozone hole by not using freon.

[Cold Heat]

NASA has already comfirmed it was insulation from the fuel tank.

You have mis-intewrpreted what NASA said. The truth is that they presented the problem to a set of engineers with the "assumption" that the insulation was the factor and they are working it through to see if it fits.

They have not made a determination as of yet. This is a exercise to determine if the insulation could have caused it. Nothing more.....

[Jael]

by Greg Katnik
December 23, l997

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:

what happened?
what phase of flight did it happen in?
why did it happen?
what corrective action is required?
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:

The primer that bonds the tank foam to the metal sub-stream was defective and did not set properly. This was eliminated as a cause because the photography indicated that the areas of foam loss (divots) did not protrude all the way down to the primer.
The aerodynamics of the roll to "heads up." The STS-87 mission was the first time this maneuver had ever been completed.
The STS-86 mission revealed a similar damage pattern but to a much lesser degree than STS-87. The STS-86 tile damage was accepted ruled as an unexplained anomaly because it was a night launch and did not provide the opportunity for the photographic evidence the STS-87 mission did. A review of the records of the STS-86 records revealed that a change to the type of foam was used on the external tank. This event is significant because the pattern of damage on this flight was similar to STS-87 but to a much lesser degree. The reason for the change in the type of foam is due to the desire of NASA to use "environmentally friendly" materials in the space program. Freon was used in the production of the previous foam. This method was eliminated in favor of foam that did not require freon for its production. MSFC is investigating the consideration that some characteristics of the new foam may not be known for the ascent environment.
Another consideration is cryogenic loading, specifically hydrogen (-423 degrees Fahrenheit) and oxygen (-297 degrees Fahrenheit). These extreme temperatures cause the external tank to shrink up to six (6) linear inches while it is on the pad prior to launch. Even though this may not seem much when compared to the circumference of the external tank, six inches of shrinkage is significant.
This is where the investigation stands at this point in time. As you can imagine, this investigative process has required many hours and the skills of many men and women dedicated to the safety of the shuttle program. The key point I want to emphasize is the process of investigation, which is coordinated amongst many people and considers all possibilities. This investigation has used photography, telemetry, radar coverage during the launch, aerodynamic modeling, laboratory analysis and many more technical areas of expertise.
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.

[Howlin]

That's exactly why this picture is a fraud.

[meema]

I don't understand why obvious fraudrulant pictures keep getting posted, either.
Tryin' to fool the sheoples, maybe. Except that this isn't the DU!!!

[garbanzo]

I think lots of things could have been designed in, but why weren't they - I'm sure engineers have come up with contingency plans. Why were they not investigated? If they were deemed infeasible then what were the standards to determine it and were they reasonable standards? Was whatever the costs of implementing those plans worth the lives of the crew and the loss of a shuttle?

[_Jim]

If tiles are the issue, I bet backing is the cause.

Early on this was one of their biggest issues - initially a felt-type pad was used to 'take up' some of the unevenness ... until a better glue and process was worked out soas tro allow the tile to be directly bonded to the aluminum surface to which it is affixed ...

[El Gato]

Windows are mainly for seeing where you're going (pilots) or for sightseeing (passengers).

Or for the "Arm" operator to see what she's grabbing onto. That's why there are windows into the cargo bay and, IIRC, on the top of the cabin just forward of the cargo bay. But maybe that comes under your first category?

[CharacterCounts]

See this thread for a great analysis of the pic

[Hermann the Cherusker]

THERE WAS NOTHING THEY COULD DO

Excellent point. I hope everyone can see past the talking heads and the finger pointers out there and realize that despite all of the technology involved, there are still accidents that can and do happen.

Thankfully, people with this attitude were not working with Gene Krantz at the time of Apollo 13.

Failure is not an option. Nor is ignorance.

[meyer]

Sure...why would com link terminate?

Ummm, the antenna burned off? Even if Columbia suffered a cascade computer failure...Nasa would have data stream...or are they withholding something?
The computer cycles as per de-orbit burn..then trim to S turns.
The computer is sequenced to adjust to S trun profile..there is an abort redundant sequence activation should descent profile go wrong.
if Columbia's de-orbit burn failed...there would be telelmetry...if Columbias profile to...and In S turn were off...Telemetry would be available...even if com link was ionized.

Ummm, if there is no link, how can the data get from the shuttle to Houston? Granted, I'm sure there were redundant links, but once they are gone, there is no way for info go get from the shuttle to the ground.

I still am in the dark understanding wise as to the distance from S turn Columbia was in when com link failed.
A detonation..a computer error in thruster activation could have sent Columbia into an unrecoverable mode.
Question remains...why the silence..even if Columbias profile was deteriorating.
Something catastrophic occured suddenly.

I agree. The loss of communications. The "big flash" as witnessed on the ground. The big "boom" some time later (remember that the shuttle was 40 miles up, a sound delay was pretty large). Don't know what to say here. There are many pieces of the puzzle being assembled as we speak by many curious people. I only hope that this will improve the space program.

[spunkets]

Here's a link from NASA with a bunch of info.

The debris was said to be urethane foam. It would be very similar to the stuff blown into boxes to pack, say, electronic equipment. The foam itself is urethane, so it's tough enough I wouldn't expect it to turn into dust as in the pics. The dust in the pic, I would expect to be silica from the tiles. The outer tile layers are ~97% void, or empty space. That's what gives it the extremely low thermal conductivity. The rest is silica membrane and fibers.

As far as trying to guess the velocity of the piece, the easiest way to do it would be to have numbered frames and a num for frames/sec. The deceleration of those 2 pieces of foam would depend on the mass, mass distribution and the cross sectional area of the foam. A ballistic coefficient can be found that would allow back calc of the mass of those objects. The rocket is moving at about mach 1.3, considering it's behind the shock cone and the foam is in a reduced pressure area, anyway it's impossible from here.

The remarkable point this couple of pics bring out is the extent of the dust envelope while the center of mass of the dust is still close to the leading edge of the wing. It's big! The pics show the piece didn't wack the leading edge of the wing. There's no dust over the top. The extent of the dust envelope means there was a sigificant bang. They can also do similar calcs to the above to determine what the dust is and how much energy was involved.

[_Jim]

The original designers of the space shuttle came up with design criterea.

.. over better than a fifty year period (if you read your history on this - you would know this) ...

[Jael]

Not looking for anyone to blame. :-)

[meyer]

Columbia's sensor grid would have detected that as heat spread Even if Columbia could not comment from Cockpit...Nasa would have the telemetry.

Depends on where the sensors were located at. Remember the loss of information from a few of the left-wing sensors? Perhaps wires were compromised as the "peel" started at a point where there were no sensors. Also note the larger rise of cockpit temperature on the left side as compared to the right.

Awwww heck, its all just little pieces of evidence. I hope it can all be put together.

[Hermann the Cherusker]

Your emphasized sentence highlights the attitude of a bureaucrat at the DMV, not a NASA Engineer. Perhaps there has been some confusion at NASA over what being an Engineer means.

[TennesseeProfessor]

There was obviously a view from the under carriage--a view the astronauts had as well as the camera.

As many others have said, this photo has no credibility. The astronauts could not have safely reached the bottom of the shuttle, and if they had they would not have seen a smokestack.