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.

[Cold Heat]

This is what NASA gets for being honest.

Some folks just don't trust the goobermint under any circumstances. Although I have been lied to many times, I tend to know when it happens most of the time and I agree that this guy is raising absolutely NO red flags.

[XBob]

yeah, the first thing I did was to blow it up. it does indeed appear to be a 'leaky' gasket which .

Notice the irregular 'tab' on the bottom left, and the very regular right side, it could have the been detached part of last cylinder port of standard exhaust header of a gasket for multi-cylinder engine with a standard flat header rather than a donut type individual headers.

[Cold Heat]

What he has been doing is opening his mind and letting all of us know what he thinks and feels.

If people keep beating on him he will shut that mouth, just like I would.

The truth is harder to believe than a lie.

Remember that, I will serve you well.

[Cold Heat]

I agree about the tab. What they are used for though is to hold the gasket while you tighten the bolts.

There is one engine I have never messed with, and that is a Mack. I wonder is that is what it is. They are more primitive than others.

[Moonman62]

This is what NASA gets for being honest.

Some folks just don't trust the goobermint under any circumstances.

I never said NASA wasn't being honest. If they were covering up they never would have showed the foam footage in the first place. I do get the sense that they are in denial. Everybody's entitled to their impressions.

[Cold Heat]

I think that tonite he was being more carefull about what he said. He has been getting beat on by many.

[Gracey]

If it is ice, as you suggest, would the ice be forming on top of the ET SOFI? I thought the purpose of the TPS was to keep the cryogenic liquids from dissipating their low temps and to prevent formation of ice (from falling?)

Are there any places on the ET where there is no SOFI? I've seen it in the VAB but can't remember any areas not covered. Been too long, and I'm getting old.

[Cold Heat]

Think it is time for horizotal recharging.

My typing is starting to suck.

G'nite All!

[XBob]

it probably fell out of a trash truck someplace.

LOL that I agree with, but notice the lighter of the dark colors on the upper right. Extremely regular.

And the raggedy part is what happens when you use a gasket with a smaller hole than the exhaust port. of course it could also be where the part was torn away, because of the leak sticking it to the part. However, look up at the dark part upper right and see how 'regular' it is, like it was sitting against the 'opening' to the cylinder, and how it corresponds to the last of the light, non leaking grey on the bottom, where it turns to white.


What ever it is, I don't think it could have come from the shuttle.

And this appears to be a 'use' defect (worn out) - not a 'blown up' defect,

But then stranger things have happened.

Well, i am going to give up this time wasting speculation.
We are both out of our areas of expertice.

[XBob]

There is one engine I have never messed with, and that is a Mack. I wonder is that is what it is. They are more primitive than others.

Almost nobody messes with Mack engines. They run forever.

[Gracey]

I worked for him.

[Gracey]

Sleep well and keep your wires intact.

[Jael]

Do you have any idea why Dittemore would not address the question posed him today regarding removing the freon?

[Jael]

Do you have any insight regarding the email mentioning that they DID take photos of the left wing, and then Dittemore saying he didn't know anything about that?

Yet in is next sentence he is talking about how the astronauts would of taken the pictures and then stowed the film away so they could take a look at it. (Mission Control?) He was saying the astronauts were aware they would be very interested in those pictures. But a few breaths before that, he is saying that if any pictures were taken, they wouldn't of been of any importance.

Here is the conversation.

DITTEMORE: We did alert the crew later on that we did have a debris impact from the tank onto the orbiter. We kept them informed of our analysis on the ground. And finally, as we have concluded that it was not going to be anything more than superficial, we alerted the crew to that fact.

I don't recall if we had any conversations from the crew to the ground, relative to the pictures that they took. Bob, do you recall?

CABANA: I don't -- I don't think there were any. Normally, the crew would take the pictures and stow that film, mark it and stow it for early return to Houston upon landing.

DITTEMORE: Especially given the knowledge that it was superficial and inconsequential, they went on with their business, stored the film and knew that we were interested in it as soon as they landed.

[Gracey]

I didn't hear todays press conference. Went to the memorial yesterday and drove home this afternoon and just got home tonight. I saw Ron Dittemore there among others. He walked over and gave me a hug. We had a 2 minute chat. I don't think he's getting much sleep... very distraught over the incident and very determined to find out the sequence of events that led to where we are today. If you were around 17 years ago, after the challenger accident, you would see night and day difference in press conferences. This is much more OPEN.

I will say that it appears the rest of NASA and contractor personnel/managers have been told the press if OFF LIMITS. Notice no one else is being interviewed, except for 3-4 NASA officials responsible for the overall Space Shuttle Program.

[Gracey]

That's an interesting conversation. Good question you have but I can't answer you, for I just don't know. I'd say that Dittemore is not cognizant of everything the crew does ans says. Most crew stuff is handled by Bob Cabana's office. He's Director of Flight Crew Ops. In fact, most all conversation between Mission Ops and the crew is done through the cap coms (astronauts in mission control.)

I don't understand how they can take pics of the left wind underside. They sit pretty far forward with relation to the wings, I believe. I'll reread but don't think I'll have an answer.

[Gracey]

OK, Here's my take. There are hundreds and hundreds of pictures taken by the crew and many conversations regarding anomalies. Many, many anomalies occur during each and every flight. This one was probably considered rather minor. You and I are seeing it in hindsight, as something of utmost importance, but at the time, it was just SOP.

Yes, I can understand the conversation, after reading it 2-3 times. It was no different than any other pics taken, that would have been of interest. They are stowed for later viewing in post flight meetings.

There are days and days of post flight reviews, where crew goes over anomalies. These take place with crew, Mission Ops mgrs and system managers, Space Shuttle managers, sub system managers....as every flight is a learning experience, and a way to make the next flights better.

I don't know if this helps. Maybe my eyes and brain are dead.

[Gracey]

Do you have any idea why Dittemore would not address the question posed him today regarding removing the freon?

As stated, I didn't hear the press conference.. Was driving back from Houston to Austin today.

Can you remember the question regarding the freon? It was removed because EPA mandated NASA to remove it. This was done by Clinton's head of EPA. NASA has also eliminated freon to "clean" the reflight parts, now substituted by water, and at an extremely expensive cost. Freon replacement has cost hundreds of millions of dollars. Everything used has to be recertified for space flight.

[Gracey]

It's the design that's screwed up.

Negative. If your theories are correct regarding the foam/ice... then I'd say the EPA screwed up....the DAMN environmentalists, that MANDATED NASA to eliminate ALL Freon. Just did a search and found this article.

.Presentation Topic : Modifications to the Space Shuttle External Tank Thermal Protection System to Comply with the New Environmental Laws By: Charles W. Williams Lockheed Martin at NASA's Michoud Assembly Facility in eastern New Orleans manufactures the External Tank (ET) for the Space Shuttle. The phaseout of ozone depleting substances (ODS) under EPA regulations has had a major impact on ET production. The ET requires a thermal protection system (TPS) to maintain the quality of the cryogenic propellants used to power the Shuttle, provide protection from aerothermal and vehicle plume heating environments, prevent formation of ice on exterior surfaces, and maintain structural integrity. The TPS is a rigid foam that initially used CFC 11, then HCFC 141b, as the chemical blowing agent to provide the critical insulation and cell structure properties. Lockheed Martin and NASA began HCFC 141b replacement efforts far in advance of the upcoming 1/1/2003 phaseout, but no replacement has been found that meets performance requirements. This presentation illustrates issues with which the manufacturers and consumers of insulating foams are faced due to the ODS phaseout program, as well as problems unique to the space program.

[Budge]

You mean you don't freep at work?

No, greeters at Wal-Mart don't have access to computers :)