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.

[XBob]

1635 - "frequency sound wave recordings indicated the shuttle exploded between the cities of Amarilla and Lubbock, about 330 miles west of Dallas."

yes i did. thanks very much. I already added it to my time/location line, but havent analyzed that. off hand, it is a bit west of where i expected, i think i estimated 200+ miles west, someplace, but it 'sounds' good to me.

[tubebender]

Do you know what the exposure of the photo was. I am curious why it doesn't show any components leaving the shuttle beside the "fuzz" off the back. I read that the breakup was well under way over Lubbek Tx not to far from the photo site. Also...was the photo cropped in any way and blown up.

[tubebender]

A certain irony to his death occurring so close to his home town...

That is pretty sobering...

[freepersup]

# 1546: If both tires blew up in the wheel well (not talking thermal fuse and venting but explosive decomp due to tire and/or wheel failure) the overpressure in the wheel well will be in the 60(?) + psi range. The resulting loads on the gear door (a quarter million lbs) would almost certainly blow the door off the hinges or at least send it out into the slip stream...catastrophic.

I too wonder if this happened ? It probably wasn't the initial spark that lit the fuse... might have been the coup de grace though ?

[freepersup]

# 1642: According to the story, (if it isn't a cover) what we are seeing is what they are seeing. I can't answer your questions- just yet.

They would have had to preset the focal length at an estimate based on the shuttle's altitude at time on target (overhead) wouldn't they ? I can't see them tracking the shuttle and adjusting the focus at the same time. I don't doubt that lots of astronomical viewing devices in our inventory have automatic adjustments of some kind or another. This sounded like a duct tape, paper clip, rubber band- patch job, that for all intent and purpose, did what it was supposed to do.

[freepersup]

# 1641: Are you charting anything out on paper (map) ?

I found the debris field locations (from local field GPS coordinants) mapped out as a graphic at NASA's site, but it is in PDF form and I haven't figured out a way to convert the information, so I can post it.

[NormsRevenge]

What is the URL to the debris field info?

[tubebender]

This sounded like a duct tape, paper clip, rubber band- patch job, that for all intent and purpose, did what it was supposed to do.

I agree...It takes me 5 minutes to compose and edit a one line reply here and then it still has mistakes.

Oh...just one more question. Was it digital or film.

[freepersup]

Without consulting a map, I'd say the location at Kirtland is around 500-550 miles from the point of estimated break up (the point halfway between Amarillo and Lubbock).

[DonnerT]

Lubbock is over 300 miles down range of Albuquerque.

[freepersup]

1647: What is the URL to the debris field info?

I'll have to find it- I didn't find it at the PDF file. I can e-mail it to you, if you want me to.

FWIW- It says: For Official Use Only.

[freepersup]

It takes me 5 minutes to compose and edit a one line reply here and then it still has mistakes.LOL

Tell me about it... honor graduate of chicken peck typing school- responding.

[NormsRevenge]

I'll pass, thanks. I don't want to stir any hornet's nest.

[freepersup]

It mimics the doppler radar images of the recent past, that reflected the heat and debris signatures of the shuttle. Imagine that info. extrapolated onto the ground and that is pretty much what it looks like.

[spunkets]

"No damage with a 16 in-lb impact.

Is the spec listed? Does it refer to the material itself, or a finished part? For this material 16 in-lbs sounds like a Charpy, or Izod test. Its a pendulum that falls from a certain height, wacks the test piece and breaks it. An Izod uses ~1/8x1/2 bar and this value sounds ~right. Just reading through the thread backwards.

[DonnerT]

Rick Husband was from Amarillo and I think the pilot was from Lubbock. If the track was half way between those towns they passed right over Earth, TX and very near the little town of Halfway, TX. Very close to home.

[freepersup]

NASA just put this up sometime today.

STS-107 Accident Investigation Ground Track and Events Summary Based on the Rev 12.1 Master Time Line (Baselined, 02/12/03, 09:00 a.m.)

[XBob]

I found the debris field locations (from local field GPS coordinants) mapped out as a graphic at NASA's site, but it is in PDF form and I haven't figured out a way to convert the information, so I can post it.

please post a link

[DonnerT]

And Halfway is almost exactly half way between Albuquerque and Fort Worth.

[bonesmccoy]

I see.
I agree with your comment.