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.

[Budge]

It looks like something is happening on the leading edge of the left wing. It follows a straight line to the anomaly on the trailing edge.

[Budge]

Will post it as soon as I get it, WS.

[Cold Heat]

Budge, you got some mail via E-mail.

[Cold Heat]

It looks like a plasma flare from that portion of the wing.

The wheel well area.

[Budge]

Here you go wirestripper.

[Cold Heat]

Appreciate the help Budge.

[Budge]

The wheel well area.

Looks that way to me too, WS.

[Cold Heat]

It also butts up to the leading edge.

The wing appears up-swept at that point, (looks that way at least)the debris smacked it at a angle that I did not see initially.

[freepersup]

Raises questions about an earlier theory about a burst tire due to a burn through and the chain of events that would ensue- rapid and catastrophic.

Minor sensor changes then total loss of all data. Rapidly unfolding catastrophic chain of events.

[Budge]

I never did buy into the 'burst tire' theory. But I'm no expert by any means.

[Cold Heat]

In the beginning, I believed the foam to have grazed the bottom, but after I ran the sequence about 100 times while tilting my laptop screen, it gave it depth and a perspective of the location.

Anyway, that is what I came up with. The tile is probably a critical one, since it borders both the wing edge and the wheel well.

If this is the cause, then both were compromised, but the well gasket and seat likely failed first causing the cover to fall away. The rest was a matter of stripping the tile underlayment off along with the tile. Eventually the skin and then loss of control due to the tremendous drag.

Going to take a nap.

[freepersup]

Nor am I an expert. I didn't give the burst tire much thought at the time. Seeing where the strike was marked on the grid paper raised the question with me just now, especially when combined with the knowledge (theory) that when whatever happened, it was rapid and severe.

Of course it goes without saying that at 12,000 - 15,000 mph an uh-oh is going to be bad.

No proof or facts to say- I think a tire burst. Just playing what if. Would a burst tire blow out the bottom of the wing ? If so, it would create a hell of a drag problem. There are sensor indications that the ship rolled or there was a yaw- first left then right. Just wondering...

I keep thinking about minor sensor changes then, (no further warning) all data is lost. I presume the shuttle was destroyed in mere seconds, following the 'event' and then the drop off of all data occurs.

So... a burst tire... blowing out the bottom of the wing... creating tremendous drag (gaping hole / hanging debris) shuttle rolls / yaws left... auto pilot compensates / over-compensates... shuttle rolls / yaws right... exposes unprotected fuselage to intense re-entry heat... shuttle disintegrates.

Just horsing around with ideas. Flame retardent suit is on and all systems functioning.

[freepersup]

I find the discourse to be fascinating as the Free Republic engineers continue to work the problem. I appreciate the opportunity to mix it up with those of you in the business and those of you in the know, and those of you that may be in my shoes, just darn interested and willing to chime in.

[FreedomCalls]

Hey it works. I downloaded the images, shrank them a little, and placed them side-by-side and used the old "free vision" or "magic-eye" technique to view them in 3-D. It makes it much more obvious what is going on with the direction and location of the foam.

[Budge]

Flame retardent suit isn't necessary as far as I'm concerned. :)

The only thing about the burst tire theory is the sensors. It would seem that a sensor would have indicated a rise in preasure. even if it were a fraction of a second before it would have burst.

I could be wrong, naturally, but that's what I think.

As slowly as the temps rose, it looks like a very fine crack might have been in the wheel door allowing that rise until t got too hot. Then all hell broke loose. But what do I know. Sigh.

[freepersup]

That slow rise in temperature lead to the cataclysmic event.

Plasma found a way into the wing... substantial reaction to the heat... something created drag... the ship reacted... the ship compensated... then total destruction...

I'd be interested in knowing how much time elapsed, once the craft reacted to the left wing event, and the moment the craft came apart ? 10 seconds, 20 seconds, 30 seconds ?

[John Jamieson]

Thats it. The left wing is trailing flame to me. The front edge has to be burning, but the Astronauts couldn't see it. The wing has to be still in basically the right shape for there to have been few aerodynamic effects at this point.

We don't have a good time for this image!?

[XBob]

452-"So... a burst tire... blowing out the bottom of the wing... creating tremendous drag (gaping hole / hanging debris) shuttle rolls / yaws left... auto pilot compensates / over-compensates... shuttle rolls / yaws right... exposes unprotected fuselage to intense re-entry heat... shuttle disintegrates. "

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glad you are coming up with what I have been trying to say for days.

[aruanan]

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.

An aerosol or dust of something that is dark when solid (like dirt, for instance) can look lighter when dispersed in the air.

[Straight Vermonter]

All data from the orbiter then stopped and the position plot display in Mission Control froze over Texas, although an additional 30 sec. of poor data may have been captured.

Maybe someone has already addressed this but the MSNBC expert (Barberi? )said this morning that NASA's computers are designed to screen out "nonsense" data. According to him there maybe relevant and possibly recoverable data that the computers screened out because they thought the data was nonsense.