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.

[John Jamieson]

I expect that this is an infarred picture of temperature. Aluminum will surely melt and probably burn at the 2500 to 3000 degree temps.

The sensor wire bundle goes right in front and down the side of the wheel well. Things are starting to fit together.

[freepersup]

With that much heat pouring into the wing at what looks like the wheel well compartment, what is the most vulnerable component ? What is most likely to burn / explode ? Makes sense to me.

Something happened after burn through to cause the ship to get sideways. We have sensors indicating a rise in temperature, we have the information acknowledging the left right motion of the ship, we have the video capture showing the ship sideways, and then we have disintegration.

[XBob]

It makes it much more obvious what is going on with the direction and location of the foam.

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great - how about comment/compare/post your estimation of the position of the hit on budge's 445.

i got a similar longitudinal position, however slightly more inboard, but no reason to disagree with budges position.

the missing wing section from budge's picture in 438 seems to show the wing missing from the wheel well forward

[XBob]

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 ?

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my opinion - the big flare over california was the wheel well door.

[XBob]

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

I think it is from an Air Force camera in New Mexico

[John Jamieson]

A piece of leading edge with structure was found in Ft Worth. It was not been established yet, which side.

It looks to me in photo that the leading edge is burning. Temperatures in the wheel well indicate fire is near but not in the well.

[John Jamieson]

Yes, but how does it fit with today's timeline?

[XBob]

462 - With that much heat pouring into the wing at what looks like the wheel well compartment, what is the most vulnerable component ?

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I would rank them in this order IMO

1. The door

2. the tires

3. the explosive bolts

[XBob]

466 - "It looks to me in photo that the leading edge is burning. Temperatures in the wheel well indicate fire is near but not in the well."

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I am not an aerodynamicist (is there such a word?) but I think it probably is the area immediately behind the leading edge.

Lay a log on the beach, and watch the sand build up in front of it, and the hole get dug behind it.

[freepersup]

The Fox, shuttle sideways video capture, represents loss of aerodynamic flight controls. This event proceeded the NM image (positive flight control). I guess the ground camerman was in Texas. Would there be a time on screen relating to the image ? One could back track from this to estimate the time in Albuquerque. Is that the question ?

[XBob]

467- Yes, but how does it fit with today's timeline?

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well, the big 'flare' over california could have been that section of the wing, and the wheel well door, one of the smaller flares.

notice, aerodynamic integrity was apparently pretty well maintained until just about Dallas.

[Doe Eyes]

So... a burst tire... blowing out the bottom of the wing... creating tremendous drag

I heard, early on, that the tires are not normally pressurized (in order to prevent damage from an explosion). Does anyone know at what point in the mission the tires are inflated?

[John Jamieson]

Good question, but I believe the tires were always inflated.

[XBob]

470- The Fox, shuttle sideways video capture, represents loss of aerodynamic flight controls. This event proceeded the NM image (positive flight control). I guess the ground camerman was in Texas.

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please reword this better.

[John Jamieson]

The sensor data DOES NOT indicate that the problem started in the tire well but on the wing in front of the tire well.

[XBob]

Does anyone know at what point in the mission the tires are inflated?

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When ever what ever gas is in them gets hot and expands

[freepersup]

The flare up begs the question- what just happened ?

As the information comes in, a picture story develops.

I want to put a flight profile image with the last known active sensor indicator readings and match the time in flight ?

I want to put a flight profile image with the loss of sensor indicator readings and match the time in flight ?

I want to know what the sensor indicator readings were when the flare up over California took place and match the time in flight ?

I want to know what the sensor indicator readings were when the military telescope image from NM was captured and match the time in flight ?

I want to know what the sensor indicator readings were when the Fox camera captured the shuttle in flight sideways and match the time in flight ?

[freepersup]

Someone here reported that the tires are inflated with nitrogen.

[XBob]

475 - The sensor data DOES NOT indicate that the problem started in the tire well but on the wing in front of the tire well.

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I didn't say it did, but freepersup asked a specific question which I tried to answer.

When/where did the sensor data indicate the problem was beginning (calif, ariz, nm, tx, etc)

[XBob]

477 - The flare up begs the question- what just happened ?

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sorry - the flares are the first question - what were they composed of. we know they happened before the other stuff.

"I want to know ...."

all good questions, and that is what we are trying to piece together her, little piece by little piece as all the disjointed little pieces are found/released.

the completed profile/time line should explain a lot of what happened, but it is too dis-jointed and piecemeal at this point, but we are gradually getting there.