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.

[WestCoastGal]

I believe this astronomer is the one who was on the phone Sunday night with Greta on Fox. He is from Bishop California and works for USGS. We also had a report on local news that a piece was found in Joshua Tree which is up the hill from us here in Palm Desert. The sheriff showed a square piece of metal with bolt holes around a square opening in the center that appeared scorched. They have contacted NASA who said it is consistent with something that could have come off the shuttle and are sending for it.

Also another report from a video filmed over Flagstaff Arizona showing something coming off. I am still looking for a good map of the path of the shuttle once it crossed over the west coast of California. Does anyone have one?

[XBob]

interesting, I don't know anything about blocking 'vents', but as far as blowing seals - we numbers of heating problems due to irregularities in gap-filler aerodynamics and very high heating.

[Cold Heat]

The sheriff showed a square piece of metal with bolt holes around a square opening in the center that appeared scorched.

This sounds like the door that is supposed to cover the opening where the strut that holds the shuttle to the tank was attached.

This could be it!

[WestCoastGal]

Here is a picture. Sorry I don't know how to post the picture directly, maybe you can add it to the thread. Thanks!!

http://kesq.static.worldnow.com/images/1116803_SS.jpg

[XBob]

I agree WS, we don't know yet, if we ever will. However, I do know that I know we "almost" lost a number of shuttles, for which they 'glossed' over, and crowed 'success'.

Those of us who worked on them, and know what shape some came back in, are just simply amazed every time one returns successfully. There are so many potential failure points.

Each successful return is 'miracle'. If the 'odds makers' who try to sell the shuttle as a 'reliable' 'truck' were to really portray the actual odds, congress would never fund it.

Designed for 100 missions? - ROTFL.

Better like flipping a coin and having it turn up heads 100 times, when you have an air hose to control the flipping by blasing at it. (bad visualization, but what I am trying to say is there is some control, and we all did the best we could - and a large percentage of luck - trying to control the uncontrollable)

[WestCoastGal]

I posted a picture of the piece found in Joshue Tree on this thread.

http://www.freerepublic.com/focus/news/835531/posts?q=1&&page=201

[XBob]

that is this thread. Please try again.

thanks

[bvw]

Have you been able to clock the motion? To some limited degree we can gauge the loss of energy by the foam (or ice or icy foam) by looking at how much speed it lost after impact on the wing. It's been said that NASA averaged 17 high speed frames (96 f/sec?) into one MPEG frame, so as enhance the image.

If they made the high speed frames public, that would even more helpful -- a full velocity characteristic, accelerations.

[XBob]

very good idea, however, beyond me and my software capabilities.

I have given the links, perhaps you/your equipment can give us an estimate.

I have seen many different shuttle 'speeds' at the point the 'insulation' came off, varying from a few hundred mph to about 1800, and also varying 'mach' speeds, which vary with altitude, so that way, I haven't got a clue, except that at 80 seconds into the mission, SRB separtion is at about 2 minutes, and not very far away, so it is going pretty fast and is pretty high. MECO (main engine cut off) is somewhere around 6-8 minutes.

[bvw]

I have to take that back, somewhat. On another thread Dugway Duke pointed out the obvious, that the wing hit would accelerate the debris, as it was moving faster, and also accelerating. Can't really do a momentum change analysis because you don't know the delta v or even the delta m.

See http://www.freerepublic.com/focus/news/836736/posts?page=247#247

[Cold Heat]

img src=<"http://kesq.static.worldnow.com/images/1116803_SS.jpg>

[Cold Heat]

Hmmm, did not workee!

[Cold Heat]

That bracket is too small for the door to the arm. It mus be a inspection port or a comm port.

How about it shuttle guys! WTF is this that was found!

[j_tull]

From the third clip, I can see how they blew this off as no damage. There is no detectable difference in the appearance of the lower wing surface after the impact. I'll bet the "Ice/Debris Team" isn't getting much sleep.

[Cold Heat]

Interesting California debris

WHat is this?

Any idea at all?

[XBob]

don't know, but if those are white gloved human fingers on the left, it appears to me to be an exhaust gasket, from the engine block to the exhaust manifold from a single cylinder of an internal combustion engine.

[Cold Heat]

Most likely a diesel.......LOL

I guess we will find out, cuz NASA is picking it up.

[bonesmccoy]

What puzzles me is that after impact, the plume from the large piece of debris does not look to follow the origional trajectory but appears to take a slightly outboard (port) track.

Yes, my eye noted the same observation. After the object disappears into or under the LH wing leading edge, there appears to be a plume that divides into two segments. The first segment appears to have debris decelerating relative to the stack. The second plume seems to decelerate but much slower than the first part (which seems to be moving at the same rate as the original object). Unfortunately I can not post the video with edits or highlights. Perhaps someone will offer their server so I can edit the photos and point out the plumes.

[bonesmccoy]

Yes, it is disappointing to come to that conclusion, but it is still early in the investigation.

Given the other problems during the mission, you have to wonder if there was something else occuring.

If significant tile damage occured, the silica either comes off or gets compressed. The silica ceramic in the tiles is very light and mostly composed of empty space.

So, the material should either fracture and become pulverized. Or, the material should be compressed.

If I recall, the tile material is friable and is not very cohesive.

If NASA has not done impact tests with scrap tiles, they should. The dust that emerges would be comparative to the impact on STS-107. If there is no dust, then the tiles may not produce a "dust cloud" upon impact.

On the other hand, if there is a substantial dust cloud, NASA could analyze the colorimetric properties and compare to the film.

[bonesmccoy]

I don't think so.

The loss of the tile should not impact the relative readings of anything. The tile is minimal in weight comparison to the entire stack. The drag is minimal compared to the controlled explosion going on inside the SRMs.

The only place where readings would be relevant is temp readings on-orbit.

I wonder if thermocouples in the LH wing structure showed abnormal readings earlier in flight (such as wider fluctuation of temperature on orbit while in the sunlight vs. shade).