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]

Remarkable work to get those diagrams.

Great work!

[bonesmccoy]

Now, who was saying something about "personal attacks"???

Why do you disagree with the descriptors of property values assigned to materials?

Are you a NASA engineer?

Or are you just blowing smoke?

[John Jamieson]

MIT/NASA true blue, but retired now. I helped design the Space Shuttle and launched the first 70 or so. How about you?

[bonesmccoy]

Are you referring to the slope of the reentry trajectory?

Just to clarify the temperature profile of the structure of the orbiter, the actual temp of a certain point in the structure is dependent upon many factors.

In fact, some points in the orbiter heat to maximum levels much later than the time of maximum heat on the TPS tiles or RCC.

The analysis of some in this thread appears to suggest that "overheating" on "wing structure" can occur quickly. These ex-NASA jocks seem to be suggesting that failure of TPS is to blame for the tragedy of OV-102's demise, with a zipper effect being discussed in multiple postings.

Contractor personnel have often been put in the difficult position of having NASA as a "customer". NASA sometimes requests engineering analyses while the agency already has a preconceived desired outcome for the analysis they are requesting. This was certainly the problem with suppression of Roger Boisjoly's SRB O-Ring analysis at Thiokol.

One wonders if such a process will be uncovered by the independent review team.

[bonesmccoy]

Great good for you.

You ever work in TPS?

[John Jamieson]

Well I didn't glue any on. But I was an Orbiter Project Manager for a while. Left it to start the KSC AI Lab in '86.

Google my name if you want, "John R. Jamieson"

[Cold Heat]

has a preconceived desired outcome for the analysis they are requesting

I have seen that little bit of business with government contracts before.

A guy doing spectro-analysis of metal plays with the machine that I just calibrated, to-get the desired result.

When asked why he screwed up the machine he say's, "I can't tell you, but it was important."

Is this what you refer too?

And yes, I believe the change with the R-12 was a problem that Michoud could not over come, so they mitigated it as best they could with what they had.

Private industry cannot afford to do such things. They have to solve the problem or belly up.

[bonesmccoy]

Great...then back off the TPS analysis for a second. You may have been the Orbiter Project Manager, but you were reliant on the Rockwell TPS guys for your Trajectory analysis.

Some of you NASA guys constantly belittle the contractors who are working on the vehicle and delivering ahead of schedule and under budget (which is what OMDP in Palmdale consistently did).

I have always been a bit irritated with the abrasive manner (which apparently continues to this day) that NASA uses to manhandle the engineering analysis from the contractors.

I seem to recall one poor soul at Lockheed at KSC named Ken Hollis. The poor guy was helping kids understand "your" program when KSC's Public Affairs Officer decided to literally strip the man of his Constitutional right of free speech. Were you involved with that fiasco 10 years ago?

I did not start this thread to attack NASA. I started the thread to understand all aspects of the accident.

While you have so steadfastly rushed to judge TPS zippering in your armchair analysis, you and the other NASA guys have not chosen to engage in the discussion of ET insulation composition and the composition of the object seen in KSC Ice Team video.

The initial reason I started this thread was to suggest a scientific method to evaluate that object's impact with the orbiter.

NASA has since released a low-resolution image of the before and after of the orbiter at the time of impact.

Initially, it appeared that some of you NASA jocks discounted the ice impact theory. Now, it appears that you and XBob are concurring that the impact correlates to the loss of TPS near the LH MLG door/leading edge RCC area.

If the object did "cause" the loss of TPS, the next question is why. The analysis is not complete unless we understand why the ET insulation changed.

Did I miss that part of the thread?
(if I did, it's my bad...but since the thread is now over 1300 posts...can you blame me if I am a working stiff and not able to follow the thread's rapid evolution over the past few days?)

[bonesmccoy]

Boy, you really hit that nail on the head.

I think the POTUS needs to consider altering the structure of manned access to space. Private industry needs to commercialize manned spaceflight to LEO/ISS. NASA can get back into the manned spaceflight business, but not to ISS. We should use NASA to get us back to the moon.

[John Jamieson]

I missed your qualifications?

[John Jamieson]

We agree on that last part. My biggest problem with NASA has always been low goals.

[Cold Heat]

In fact, some points in the orbiter heat to maximum levels much later than the time of maximum heat on the TPS tiles or RCC.

Yes, I was referring to the glide path and yes, I understand NASA has encountered heating situations before and have changed tile arrangements and improved the tiles to fix these things.

I am satisfied in my mind that it was a TPS failure of a critical nature under the left wing.

The debris hit was the likely cause and the fix is to do something with the tank insulation. What, I do not know but there are new foams on the market to test. There are new materials to invent and there is a will to do it.

[bonesmccoy]

I won't post "qualifications" because I want anonymity here.

Suffice it to say that I know enough about the NASA-Contractor relationship to really p.o. an old NASA man like you.

Some of my comments probably hit close to home. I respect older guys who have made tough calls and can prove it.

What I don't respect is people who attack others personally instead of focusing on the physics, materials science, and the engineering.

When a discussion starts to digress into personal attacks and calls for "credentials", I know that emotions are still on high (for some reason...usually subconscious guilt).

If someone knows what acronyms like TPS, OMDP, KSC, OPF, and RCC are, do you seriously think they were NOT involved in the program?

[John Jamieson]

"What I don't respect is people who attack others personally instead of focusing on the physics, materials science, and the engineering."

"When a discussion starts to digress into personal attacks and calls for "credentials", I know that emotions are still on high (for some reason...usually subconscious guilt)."

I believe this started when you questioned mine.

[bonesmccoy]

Yes. I was attempting to point out that some parts of the orbiter sustain max heat loads as late as landing or even later. That is the reason that the recovery team includes vehicles for cooling. Other recovery vehicles handle atmospheric monitoring and control of volatiles.

[bonesmccoy]

No... it started with XBob and you with the request for credentials on Snopercod.

Stay focused on the physics. The physics doesn't lie.

I've got an honest disagreement with XBob regarding the interpretation of the USAF photo. He seems to think that TPS damage was massive and specifically involved the RCC.

If the USAF photo shows an open MLG door and intact RCC, the terminal events were the result of something other than massive TPS debonding (which is what you and XBob are arguing).

While I accept that the videos show separation of material from the orbiter while over CA, AZ, and NM; I had posited a technical question (which was overlooked by you guys).

The question was whether or not plasma at Entry Interface can create "flashes".

I have seen many videos of orbiter entries which show a flickering plasma around the crew module and even in the overhead windows as the plasma pulses and flows around the vehicle.

Care to comment?

[bonesmccoy]

Regarding "internal" causes, I have posted a request for info on the temp limits on the pyros in the MLG bay. However, no one has posted a response. It is probably a technical detail that NASA and Boeing have.

I've wondered if the max thermal limit of the pyros were exceeded near the time of loss of signal.

[Cold Heat]

Mock-up of wing to be tested
Also on Tuesday, NASA said it will begin testing a mock-up of shuttle's left wing.

The analysis, to be conducted in high-speed wind tunnels, will look at four possible patterns of damage and how the wing's temperature and stability would be affected under each, Scott Hubbard, a member of the team investigating the accident, said Tuesday.

"If a big chunk of tile is missing, then what?" Hubbard said.

The debris finding is important to the shuttle investigation because many of the problems involved the left wing before the spacecraft broke up during a re-entry attempt on February 1, killing all seven astronauts onboard.

The Columbia investigation board continued to meet Tuesday. It has opened an office near Johnson Space Center.

Board members are expected to leave Wednesday to spend part of the week visiting other NASA centers. There, they will study how shuttle hardware is developed, built and tested, as well as how shuttle operations are conducted, NASA spokesman Dave Youngman said.

The board's chairman is Harold Gehman Jr., a retired admiral who investigated the 2000 bombing of the USS Cole.

"I'm comfortable we'll solve it," Gehman said Tuesday. "The professional team I have here has solved accidents with less evidence."

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Copyright 2003 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten, or redistri

[bonesmccoy]

wow... i'm in awe (and that's NOT being sarcastic)!

Answer to Hubbard: If a big chunk of tile is missing, then we'll know that the ET insulation failure may have predisposed the orbiter to failure on re-entry.

More importantly, it will permit Michoud to discuss the negative impact of Clinton-Gore environmental policy on our nation's progress in materials science.

[Cold Heat]

I figured you would be interested. This is a little bit different NASA than the Challenger NASA was.

Another report I heard today that caught my attention was that the ISS astronauts have approved and accepted the possibility they may be there for as much as a year and a half.