Observation on TPS damage on Orbiter

NASA photos | 2-3-03 | BoneMccoy

[bonesmccoy]

In recent days the popular media has been focusing their attention on an impact event during the launch of STS-107. The impact of External Tank insulation and/or ice with the Orbiter during ascent was initially judged by NASA to be unlikely to cause loss of the vehicle. Obviously, loss of the integrity of the orbiter Thermal Protection System occured in some manner. When Freepers posted the reports of these impacts on the site, I initially discounted the hypothesis. Orbiters had sustained multiple impacts in the past. However, the size of the plume in the last photo gives me pause.

I'd like to offer to FR a few observations on the photos.

1. In this image an object approximately 2-3 feet appears to be between the orbiter and the ET.

2. In this image the object appears to have rotated relative to both the camera and the orbiter. The change in image luminosity could also be due to a change in reflected light from the object. Nevertheless, it suggests that the object is tumbling and nearing the orbiter's leading edge.

It occurs to me that one may be able to estimate the size of the object and make an educated guess regarding the possible mass of the object. Using the data in the video, one can calculate the relative velocity of the object to the orbiter wing. Creating a test scenario is then possible. One can manufacture a test article and fire ET insulation at the right velocity to evaluate impact damage on the test article.

OV-101's port wing could be used as a test stand with RCC and tile attached to mimic the OV-102 design.

The color of the object seems inconsistent with ET insulation. One can judge the ET color by looking at the ET in the still frame. The color of the object seems more consistent with ice or ice covered ET insulation. Even when accounting for variant color hue/saturation in the video, the object clearly has a different color characteristic from ET insulation. If it is ice laden insulation, the mass of the object would be significantly different from ET insulation alone. Since the velocity of the object is constant in a comparison equation, estimating the mass of the object becomes paramount to understanding the kinetic energy involved in the impact with the TPS.

3. In this image the debris impact creates a plume. My observation is that if the plume was composed primarily of ET insulation, the plume should have the color characteristics of ET insulation. This plume has a white color.

Unfortunately, ET insulation is orange/brown in color.

In addition, if the relative density of the ET insulation is known, one can quantify the colorimetric properties of the plume to disintegrating ET insulation upon impact.

Using the test article experiment model, engineers should fire at the same velocity an estimated mass of ET insulation (similar to the object seen in the still frame) at the test article. The plume should be measured colorimetrically. By comparing this experimental plume to the photographic evidence from the launch, one may be able to quantify the amount of ET insulation in the photograph above.

4. In this photo, the plume spreads from the aft of the orbiter's port wing. This plume does not appear to be the color of ET insulation. It appears to be white.

This white color could be the color of ice particles at high altitude.

On the other hand, the composition of TPS tiles under the orbiter wings is primarily a low-density silica.

In the photo above, you can see a cross section of orbiter TPS tile. The black color of the tile is merely a coating. The interior of the tile is a white, low-density, silica ceramic.

[bonesmccoy]

Based upon the volume, size, and color of the plume; one wonders if the plume in the last frame has significant amounts of tile silica and only minimal amounts of insulation or ice. This would give the relatively large amount of white plume for such a small object.

Another freeper noted that the orientation of the insulation/ice object changes the impact force based upon the surface area of the impact. The individual made the observation that if the object had impacted "edge" on, the damage would be greater than if the object impacted flatly on the leading edge.

The white plume seen in this frame may be partly composed of silica particles from pulverized tiles. Given the substantial size of the plume when compared to the relatively small size of the object, one wonders if the plume size is actually the density and size one would expect from an insulation approximately 2 feet in diameter.

Once it is established that ET insulation alone can not create the plume seen (via the colorimetric test), it should be possible to create a second test scenario. A mixture of ice and ET insulation can be created to mimic estimated launch conditions. That mixture should be fired at the test article and the plume colorimetrics studied.

The resulting data could be compared to the photographic evidence and permit the composition of the plume to be evaluated in a scientific manner.

It is my contention that if one compares the plume from a 2' piece of ET insulation to the plume in the photo: 1. The photo has a plume with greater white tones 2. The photo has a plume in greater size than expected. 3. The differences in size of plume and tone are accounted for by silica pulverized by the impact.

Knowing hindsight is always 20/20, I welcome discussion and criticism. This posting is meant to contribute to the scientific process and only suggests one scientific method to approach the accident investigation.

Thanks... God bless and rest the crew of STS-107 and 51-L.

[Mo1]

BTT for a later read ..

[bonesmccoy]

Thanks for the bump Mo1.

Snopercod...your comments?

[Cold Heat]

Interesting.

I wonder though, whether or if ice was invoved, would the plume not have some prismatic effect as light reflected off of it?

[Cold Heat]

What the ell happened to my ls!

[neutrino]

Impressive analysis!

[Lion's Cub]

I'm not a scientist and probably shouldn't speak up, but I'm wondering if the colors you are relying on are due simply to the highlighting?

In all photos but that above point 4, the ET has a reddish-looking thing near the bottom of the picture. The highlighting does not occur in this area.

In the picture above point 4, where the highlighter does cover that area, the previously reddish-looking thing is now white, yet the plume does not appear to have extended far enough to have produced that white color.

I'm neither disputing nor defending the tile theory because I simply don't understand enough science to argue for one or the other. I'm just pointing out what I see :)

[brityank]

Bump and ping for reference.

I have a slow connect to the web, so these are the first real close-ups I've seen. What type of camera/film are these images made with? It seems they are not 'normal' but are IR enhanced [much like 'night-vision' rectifiers] and therefor the colors would be warped. Having seen someone hit and sliced open with a less than 1/2inch slab of ice from a building, I think your synopsis is right on the money. Thank you.

[Lion's Cub]

If you are right about the IR camera, then the tile damage might account for the color change in that reddish thing that's highlighted in the picture above point 4. If the tiles were automatically reflecting the heat, that thing might have been reddish. If the tiles quit reflecting the heat, the reddish thing may have cooled some.

[Mo1]

I do have a question

It has been reported that on other shuttle missions that ice and foam have fallen off

Are there any photo's of those times and maybe they could be compared to this one

I know you really can't compare, but I have no idea what this foam looks like ..

[exnavy]

That's all well and good reasoning. One thing to note though, last night I watched a NASA spokesman speak to the occurance of a significant "heating event" above the left wing and up into the wall or side of the orbiter above the wing. This implies the tile loss and underside heat was nearer the inboard or base of the wing.

[brityank]

I mentioned the IR enhanced, because on my monitor, I omly see greenish shades with black sky and white main body; the only hint of reddish tint is in the extreme lower left of the SEB plume.

[Moonman62]

Ron Dettemore mentioned the color during his press conference yesterday. He noted that the color could be called light rather than white. I got the impression he was stalling and playing rope-a-dope. He knows the color is significant just like you've noted, and one day he's going to be held accountable.

[Cold Heat]

This is interesting, and I wonder if it was still aboard for this flight. Apparently the heating of the side wall of the shuttle is nothing new.

SHUTTLE INFRARED LEESIDE TEMPERATURE SENSING

The SILTS experiment will obtain high-resolution infrared imagery of the upper (leeward) surface of the orbiter fuselage and left wing during atmospheric entry. This information will increase understanding of leeside aeroheating phenomena and will be used to design a less conservative thermal protection system.

SILTS provides the opportunity to obtain data under flight conditions for comparison with data obtained in ground-based facilities. Six primary components make up the SILTS experiment system:

(1) an infrared camera,

(2) infrared-transparent windows,

(3) a temper ature-reference surface,

(4) a data and control electronics module,

(5) a pressurized nitrogen module and (6) window protection plugs. These components are installed in a pod that is mounted atop the vertical stabilizer and capped at the leading edge by a hemispherical dome. (The SILTS pod replaces the top 24 inches of the vertical stabilizer.)

Within this dome, the infrared camera system is mounted in such a way that it rotates to view the orbiter leeside surfaces through either of two windows-one offering a view of the orbiter fuselage and the other a view of the left wing. The camera is sensitive to heat sources from 200 to 1,000 F.

The camera's indium-antimonide detector is cooled to cryogenic temperatures by a Joule-Thompson cryostat. The camera's field of view is 40 by 40 degrees. Its rotating prism system scans four 100-line fields each second, with a 4-1 interlace, resulting in a 400-line image.

Each of the two infrared-transparent window assemblies consists of dual silicone windows constrained within a carbon-phenolic window mount. The windows and window mount assemblies are designed to withstand the entry thermal environment to which they would be subjected without active cooling. They are, however, transpiration cooled with gaseous nitrogen during experiment operation so that they do not reach temperatures at which they would become significant radiators in the infrared. A small thermostatically controlled surface between the two window assemblies provides an in-flight temperature reference source for the infrared camera.

The pressurized nitrogen system comprises two 3,000-psi gaseous nitrogen bottles and all associated valves and plumbing. The pressure system supplies gaseous nitrogen to the cryostat for camera detector cooling, to the external window cavities for window transpiration cooling, and to pin pullers that initiate the ejection of the advanced flexible reusable surface insulation window protection plugs upon SILTS activation to expose the viewing ports and camera.

The information obtained by the camera is recorded on the OEX tape recorder. The data, when reduced and analyzed, will produce a thermal map of the viewed areas.

The SILTS experiment is initiated by the onboard computers approximately five minutes before entry interface, which occurs at an altitude of approximately 400,000 feet. The camera operates for approximately 18 minutes through the forward-facing window and left-facing window, alternating evenly between the two about every five seconds.

After the six planned SILTS missions, an analysis of structural loads will determine whether the SILTS pod should be removed and replaced with the original structure or remain in position for other uses. The pod thermal protection system is high-temperature reusable surface insulation black tiles, whose density is 22 pounds per cubic foot.

[Cold Heat]

BTW, This system was only on the Columbia......

[brityank]

After the six planned SILTS missions, ...

This system was only on the Columbia......

When was this started? Did NASA cut it back to 2 or 3 flights to save funds?

IF they had it, and find it, it could be invaluable. Thanks.

[Cold Heat]

That info was not on the site. I assume it was there, but who knows. I thought it might be indicative of a re-occuring problem with heating on the left side of the orbiter.

They were attempting to find out why.

[Jim Noble]

Ok, people, let's work the problem bump!

[Cold Heat]

MSNBC just ran some fantastic pics and videos of the insulation incident. Some were real close ups.

The hue of the dust was definately redish. I have no doubt.

NBC also verified the voracity of the reported tile loss over California. They said the guy was a astronomer with a telescope.

[rintense]

Bump to read later...

[small_l_libertarian]

On Fox News during Cavuto's repeat show last night, they had a very clear video of the insulation/ice falling off of the tank and hitting the wing. At the end of the video when the plume sprays out, you can very clearly see that the original "chunk" also comes out from under the wing.

The plume appears to be tile dust to me, too, but I'm basing it on the fact that I saw the chunk come out from under the wing, pretty much the same size/shape it went in, not the color of the plume (looking at the color was a very good idea, though).

(Now, I was viewing this video at midnight, so it may just be my eyes...)

[snopercod]

Thanks. Those are the best photos I've yet seen of the "debris". Here are my thoughts:

1. It looks like ice to me, too, not ET TPS. My guess is that it came from the ET LH2 repress line, the 2" line that runs up the left side of the tank which is used to repressurize the ET LH2 tank as the LH2 is sucked out of it during ascent. IIRC, the ET LH2 Repress Line is at ambient temps pre-launch, but pressurized with hot gasses from the engines on ascent. That could have melted off a chunk of ice.

2. Take a second look at the launch video and you will see frost actually growing on the intertank during ascent. Atmospheric conditions must have been right for ice built up on that line or it's attachments during pre-launch or ascent.

3. The impact area looks to me to be very close to where the LMG door was located. The white "vertical" line you see in the "enhanced" areas is the "bond line" between the wing and the fuselage. (It's not really a line, but just a change in curvature in the tiles which appears as a line in reflected light.)

4. The hinges of the 4'x12' +/- gear doors are along the bond line, and the door swings outboard upon closing. The front-outboard corner of the gear door is ligned up with the point of the leading edge where the chine sweeps outward. In picture #3, you can see that plume on the right side of the enhanced circle sweeping directly over the leading edge of the LMG door area. The front-outboard corner of the door is less than 3' away from the leading edge of the wing! (The main impact in the photos seems to be inboard of the bond line.)

5. The landing gear door area is one of the hottest areas of the shuttle on re-entry (second or third only to the nose cap and leading edges, I believe)

(I have the shuttle tile drawings in front of me as I type this. I haven't found my ET drawings yet. We boxed everything up when we left KSC...)

[snopercod]

The SILTS pod is still there (that bulb on the top leading edge of the vertical stabilizer). But to the best of my knowldege, they haven't flown the camera for ten years or so.

[lysol@whitehouse]

Observing Monday's news conference, Ron Dettemore's composure appeared to dramatically change when asked about the possibility of ice on the insulating foam, and how that would change estimates of damage to the tiles. His voice hardened and became loud as he appeared to obfuscate and hide behind "intelligent men assessed all possibilities and decided there was not a problem". None of the reporters challenged him at this point, following up with a marshmallow question of "what about the future of space flight?" Reminds me of the Challenger news conferences. Bless the heroes of Columbia.

[exnavy]

On Sat. afternoon I heard a nasa spokesman say "there was a midcourse autopilot correction due to extreme high level buffeting and turbulance". Do you suppose that turbulance could have caused the loss of more loosened tiles than would have normally occured?

[OldFriend]

Your analysis is the very best to date. Thanks for making it simple to understand and sounding so logical.

[snopercod]

I just saw the same stop-frame video on Fox. What looks like a plume in pic #3 wasn't moving, so disregard what I said about it in my paragraph #4.

[OldFriend]

There may not have been sensors where the event originated.

[snopercod]

Turbulence is a concern, but I think it might have caused ice to fall off, not tiles. The tiles are stuck on there real good.

[michigander]

A piece of what is believed to be the underside and rear of the left wing of the space shuttle Columbia lies
against a fence near Nacadoches, Texas, February 3, 2003. During liftoff a piece of insulation hit Columbia's
left wing and NASA officials said Monday that it could have smashed into the some of the more than 20,000
thermal tiles covering the craft. REUTERS/Rick Wilking









A closeup view of tiles on what is believed to be the underside and rear of the left wing of the space shuttle
Columbia near Nacadoches, Texas February 3, 2003. During liftoff a piece of insulation hit Columbia's left
wing and NASA officials said Monday that it could have smashed into the some of the more than 20,000
thermal tiles covering the craft to protect it from burning up on reentry. REUTERS/Rick Wilking

[Budge]

Good, Bones. That plume has had me intrigued from the first. Whatever the object is/was, insulation from the ET, ice, or a combination of the two, it was large before the impact.

As far as the plume, I wonder if the size would be consistant with only the object being shattered. Personally I don't think so, but that is only MHO.

[small_l_libertarian]

I think I see the chunk in this series of stills, as well.

Debris Stills

In the last two frames, I can see the "chunk" (when the plume sprays out) come out from under the wing, and pass in front of the SRB (down toward the bottom of the SRB, near the small orange bit showing).

Does anyone else see this?

[bert]

.....ET insulation is orange/brown in color......

..... The interior of the tile is a white.....

It seems to me these statements are contradictory. Based on long ago upclose observations of the material, I thought it was white throughout with a black exterior surface.

If a tile sheared off as opposed to becoming unstuck, the exposed sheer surface would be white. If on impact the fragment disintegrated into a powdery cloud, the appearance would be light colored, in, fact would be reflective, and would be visable as a plume.

Similar visable phenomena would result from an ice blob so I can reach no conclusion.

[sam_paine]

So if it was a plume of smashed tile, then there should be some evidence near the launch site, or perhaps residue on the SRBs? I assume it was fairly far downrange when this occured, thus over water? Oh well.

[Budge]

I keep going back to the slo-mo pictures on Florida Today's site. I noticed that in about frame 10 and 11 (if I am counting correctly) that there is a small plume that appears under the wing immediately before the large plume in appears in frames 12 & 13.

Am I seeing correctly? Is that an additional small plume or perhaps something in the background?

[Revelation 911]

yeah I saw it - I also noticed there was enough material (be it ice, foam or tile) to swirl behind in the turbulence

[Budge]

I can see the "chunk" (when the plume sprays out) come out from under the wing,...

I see that also, S1L. It appears the plume actually "splits," so to speak, and the chunk is to the left side of the 'split.'

Does anyone else see the small "plume" in frames 10 & 11?

[okie01]

"This information will increase understanding of leeside aeroheating phenomena and will be used to design a less conservative thermal protection system."

I read this as suggesting that they weren't experiencing recurrent overheating on the upper left wing and fuselage. Instead, they believed that they were "over-insulated" and could potentially implement a "less conservative thermal protection system". In other words, save a couple of pounds...

[ijcr]

Firstly the chemical composition of the foam insulation was changed recently due to the ban on the use of freon. The "new" foam doesn't maintain integrity quite as well under high heating conditions and some pieces have been coming off, so NASA sands the foam still thinner to design "minimums" to still protect the aluminum skin, yet decrease the amount of foam that potentially could come off.

Secondly, All the tanks come in from the factory a light tan in color, and can eventually reach a chocolate brown depending on how long it sits on the pad in the sun. Any orange tinting should be very subtle. Actually, the orange influence is attributed more to what the sunlight is contributing that day whether it be close to sunrise or sunset than anything else.

Thirdly,The super-lightweight ET's, which first flew in 1998, have an even lighter color.

Finally, public affairs now shoots a lot of their images with digital cameras and these cameras sometimes have trouble reproducing reds, yellows, and tans.Often in filming a rapid event will go to white,eg fill a balloon with a dark powder and film it being burst...the result is often a white cloud.

[RippleFire]

Something else of interest from http://brian.carnell.com/articles/2003/02/000003.html

More on Shuttle Foam Damage from STS-87

By Brian Carnell

Monday, February 3, 2003

This NASA page has notes by a NASA worker from 1997 about the "significant damage" done to STS-87 from the reformulated, Freon-free foam insulation flaking off during the Shuttle's ascent (emphasis added),

 

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 unlikly, 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.

And intriguing comments about similar issues during STS-86,

 

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.

[Cold Heat]

You may be right. I thought the opposite of less conservative would be more liberal> LOL!

[Fitzcarraldo]

Excellent analysis! The way the solid object became a plume is significant. If that is shuttle tile pulverizing there was a real problem...

[small_l_libertarian]

I do see what might be a small plume before the large plume, but it may be a trick of sunlight. These photos are pretty dark, so it's hard to tell.

Fox News and MSNBC both have some very good video of this that they've been showing for the last two days. I will watch for the small plume and see if I can see it better in the video.

[AxelPaulsenJr]

Budge, what about the reports this morning that the trouble for the shuttle may have started a minute earlier thatn NASA had been saying? I heard they are now saying the trouble started at 8 minutes before the crash, not 7 as originally thought.

Where would the eight minute timeline put the shuttle over the earth as it was descending?

Thanks, Axel

[Budge]

Trick of sunlight...

That is why I was asking. I can't really tell.

I've only seen the video on FOX and assumed (silly me) that it was the same as the video FL Today has.

I honestly don't know about the small "plume" I see. But I thought it was worth bring up. Thanks.

[spunkets]

Here's a page from NASA with 3 mpegs of the debris hit. It looks like ice rather than foam, because the foam is too resilient to explode like that, larger frags leaving the impact area would be evident. If the ice weighted 1 lb and was going 300mph, it would have 6K ft-lbs of energy. Since it was bigger than pint size, I'm sure it had more. The ship was said to be going ~1000mph(mach 1.3) at this point. I also e-mailed NASA to get the frame rate of those flicks. If they answer, I'll post it.

[small_l_libertarian]

They may very well be using the same video, but what the news channels are showing is much clearer and brighter.

Maybe they just enhanced what they all have? (I have no idea how that works.)

[Starrgaizr]

"the object is tumbling"

the object is accelerating, relative to the Orbiter. The Orbiter is at maximum acceleration UP and the object is rapidly deccelerating as it is not aerodynamic and it is tumbling.

Also, how massive must a piece of ice be to withstand the relative wind as an intact piece of ice rather than be smashed to smithereens by the "slipstream" prior to impacting the wing?

The latter suggests at least some insulation, no? Would ice hold together? If so, it would have to be more than a thin, low-mass sheet.

[Budge]

Budge, what about the reports this morning that the trouble for the shuttle may have started a minute earlier thatn NASA had been saying?

I don't know, and can't confirm just when the trouble started.

NASA is reviewing the tape from the Australian astronomer in California that he took as it was passing over. It clearly shows something comming off Cloumbia then. That alone would put the beginning of trouble earlier.

Then there is the video the two young men took as it passed over Nevada. It clearly shows something comming off. They even comment on it on the tape. What I have no idea is, is that he same pice that the fellow in California saw and photographed, or another piece.

As far as your origional question of the time line, it will take someone much smarter than I to determine just that put Columbia. I'm thinking in the California/Nevada area though. Perhaps Snooperpod or bonesmccoy can better answer.

[elfman2]

I agree