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]

I played your link, but did not see the object you are referring to.

Perhaps there are more frames on another website that we can post?

[bonesmccoy]

Mo1,
The ET insulation is orange-brown.

Previous missions have not had debris this large hitting the orbiter TPS.

Small ice particles can make pock-marks on the TPS under the vehicle. Those photos are countless.

[bonesmccoy]

thanks for your positive comments and your encouragement. God bless!

[bonesmccoy]

SRM's land in the Atlantic Ocean. Only significant impact damage would be identifiable on the SRBs. Coating of silica would not be likely to survive ocean impact.

[Jim Noble]

The SRBs are a compromise as it is, and were opposed by most in the beginning because of safety issues (You can't turn 'em off).

I think the manned component and the cargo component should be separated, and soon. I'm not sure I would let the shuttle fly again.

Any manned component, though, will likely use liquid fuel.

[bonesmccoy]

YES! I now see what you are referring to.
The small plume appears to be about the orientation and momentum of the original object.

Does the larger plume appear to originate from a more lateral or port origin than the smaller plume that you see in frame 10 or 11?

In reviewing the Florida Today sequence, you definitely see two separate plume densities. Most interesting!

[Justa]

Dude, go for broke. Check out the last frame of the sequence. There's a 'flare' of white as the debris approaches the exhaust. That ain't insulation, it's steam!

[bonesmccoy]

Good points.

At that altitude (ironically just greater than 200,000 feet) the vehicle is moving through Maximum aerodynamic pressure (Max Q) but the ice chunk probably would not sublimate. Turbulence in the atmosphere would probably not break up the ice chunk, because the turbulence probably wouldn't impart shear forces on the object. I would surmise that fractionation of the object would require sheer forces from the "slipstream" with differing vectors. Toss a piece of paper out of a window at 80 mph and you won't see shredded paper. You'll see a paper flipping and tumbling out of control. Hold the paper on one corner (imparting a opposite force from the force imparted by the turbulence) and you see shredding.

There must have been a larger ice chunk. The piece we see may have been only one part of a larger sheet on the ET.

KSC's PAO has posted better resolution video files.
http://www-pao.ksc.nasa.gov/kscpao/shuttle/countdown/sts107/vidtoc-b.htm

Clip One
http://www-pao.ksc.nasa.gov/kscpao/video/E212.mpg

This is the same angle as on the Florida Today website.

The initial frames are a bit confusing to an untrained person. You can see multiple white objects in a few frames. However, the forward orbiter attachment is between the tumbling white object and the camera. It appears that the object slides between the forward ET-orbiter attachment posts.


http://www-pao.ksc.nasa.gov/kscpao/video/ET208.mpg

This is a view of the stack port side and shows a large chunk of tumbling ice falling off of the area near the ET intertank region (area between the LOX and LH2 tanks).


http://www-pao.ksc.nasa.gov/kscpao/video/ET208Mag.mpg

This is a magnified and digitally enhanced view of the ice chunk appearing between the ET and orbiter.

[freepersup]

I have been asking the question to no one in particular, why NASA keeps mentioning insulation ? Do they have proof it was insulation ?

Many threads and posts ago, I went with ice as the likely object, mainly- because after reviewing the video the spray coming off of the wing appeared to me to be just that, spray.

Not a cloud of dust per se. Not dust, in the sense that the foam disintegrated into dust. This didn't make sense. I had a hard time picturing the foam (flexible) turning into a pulverized state upon impact.

The supposition by the author, does make sense if in fact the spray (my description) is not in fact ice particles but is tile particles (dust). Or more likely, the spray is a combination of pulverized ice particles and the resultant dislodged tile material in the form of dust.

My lay theory: it's ice (unfortunaely 100% relative humidity at launch) striking the fragile tile, pulverizing the ice and tile into an ice spray-dust cloud combination, that we see cascading into the left booster rocket thrust flume.

[bonesmccoy]

I believe that the astronomers were at the Cal Tech radio telescope array in the Owens Valley. The Owens Valley is a very dry environment East of the Eastern face of the Sierra Nevada range. NASA would need to triangulate the videography done at Owens Valley with the videography in Nevada to evaluate if it is the same piece.

Since the orbiter is 50-60 miles high at that point, it is entirely possible that the two videographers noted the same event. Where was the videographer in Nevada?

[bonesmccoy]

The shuttle program director is only the last stop in the decision tree. The investigation will elucidate where the messages went.

Pointing fingers at one person is not responsible.

This vehicle's success was due to the efforts of thousands of workers. The vehicle's demise is also due to the mistakes of hundreds of people throughout the decision tree. The crew didn't return safely and that crushing reality is more painful than your off-handed commentary.

[bonesmccoy]

Saw your correction now.

Saw the video.

That video is unlikely to reflect the occurances observed by the astronomers in California.

It appears the vehicle was shedding material prior to the loss of communication over Texas.

[bonesmccoy]

A smaller spaceplane on an expendable launch vehicle has been conjectured for 15 years. The project was called HL-10 and was proposed to the Clinton Administration.

I was very disappointed that Vice-President Albert Gore chose to give money to the decaying Russian space team rather than fund US assembly lines to build the HL-10.

Had Clinton-Gore funded HL-10 as Congressional Republicans were requesting, the orbiter assembly lines in California could have remained viable. When Clinton chose to ignore HL-10 as a project, he killed the economy in Los Angeles and forced LA's economy into total control of the entertainment RATS.

Now, we have no way of replacing OV-102 and we can't build HL-10 unless a massive gov't spending program occurs.


Thanks Bill.

[tophat9000]

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.

Yes I saw this too... but it looked to me to be in larger chunks

[bonesmccoy]

Sorry to disagree. However, review of the KSC PAO mpegs clearly shows a white object tumbling through the FWD ET attachment posts. It's tumbling like a giant pancake of ice through the posts.

To my "uninvolved" eye, it is obvious.

The question is not if it is ice.

The question is whether or not NASA consulted with Boeing's shuttle TPS engineers.

[bonesmccoy]

Your numbers are pretty damning.

Of course, our discussion is occuring after the accident.

The mass of the object is difficult to assess. The problem is that the fwd attach point between the orbiter and the ET obstructs the view of the object.

The NASA engineers may have underestimated the size of the object.

Still, the mission was doomed. Even if they had done an EVA to evaluate the wing damage, there is no way they could have repaired the damage or rescued the crew (unless the next flight was rushed to the pad and risked to save the crew).

[bonesmccoy]

I believe that the ET insulation is layered on.

However, I do not know much about the ET insulation.

I was hoping another would comment.

[bonesmccoy]

Perhaps. Bernoulli would be proud of you :)

There are several frames of video with the object above the attach bars. Only one frame of video with it below.

My verdict is you are correct!

[bonesmccoy]

I'm not sure which frame you are viewing :(

I'm looking at the KSC PAO mpeg E212.

The last two frames show the plume to be expanding and still present as it passes into the SRB and SSME exhaust plume. If silica tile dust passes into SSME exhaust, does the SSME exhaust plume change color?

[bonesmccoy]

dittos. but we have the benefit of 20/20 hindsight.

It's far harder to predict the event given a scant film and little other data.