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.

[DonnerT]

Also looks like the whole vehicle is in about a 5deg. slip.

[TigersEye]

bttt

[bonesmccoy]

Your argument is logical, persuasive, and factual.

It appears that the US Congress is unable to permit persuasion to assist in design of actual policy.

[spunkets]

Shuttle in flight

[John Jamieson]

Cool, I haven't been able to flip it (mirror image?) to match. I also have a scan of the "glove", maybe tomorrow.

[spunkets]

Wing structure

[XBob]

yes,that's what the picture is all about, I thought it was fairly obvious.

the wing, next to the body and forward of the wheel well appears to be missing.

[capitan_refugio]

Good science, bones. Hypothesize, test, analyze, conclude, and re-hypothesize. That is how NASA should be doing it. I only wish they had considered some "worst case" scenarios before they brought those poor souls home.

[XBob]

547-"Might that suggest a larger impact or grazing area -- covering more than the space of just a couple of tiles?
"

---

I don't know - the imact area was rather compact and spread widely. I would recommend taking a cup of flower and put it out the window, while driving down the road, if it weren't so dangerous. What ever it was, it sure did spread out, and fast.

[spunkets]

There's also a page from NASA Shuttle pages that describes the RCC edges. _Jim also has a link to a pdf with a pic of the edge components.

[XBob]

note the roughness of the pixels on the picture of the missing wing portion, and at first I attributed the irregularity to the diagonal/pixels, and the angle, however, in looking at it again, it seems to irregularly ragged (not a straight line - look at the edge of the other wing) and it seems to curve inward in the main part of the leading edge.

perhaps nearly the whole leading edge of the wing stripped off, when the front part pulled off.

[Budge]

The closest time line we have so far is in the post by wirestripper, #380.

I would like to have the graphs with time line NASA showed on the press conference yesterday. They were to the second. Maybe they are posted somewhere.

[Budge]

I agree. Both leading and trailing edgees are burning. Going to look for a more exact time line.

[Budge]

Thanks for posting the link.

Here it is in text.

Dittermore emphasises several times the times are not exact and will change.

7:52:00 sensors normal
7:52:20 left main gear brake line rise 2 degrees min
7:52:39 left main gear brake line A - 6 degrees
7:52:48 LMGBL C 5 degrees/min
7:52:59 Left inboard elevon first indication of rise in temp goes off line
7:53:10 Hyd Sys Left outboard elevon actuator return line goes offline
7:53:11 Hyd Sys Left inboard elevon actuator return line goes off line
7:53:11 Hyd Sys left outboard elevon actuator return line goes off line
7:53:36 Hyd Sys left inboard elevon actuator return line goes off line
7:54:13 LMGBL temp B off nominal rise - 6 degrees/min
7:54:22 Mid fuselage left body line temp at x1215 - off nominal rise 6 degrees/min - not connected to wheel well wiring bundle
7:54:27 LMG Strut actuator begins to rise - 7 degrees/min
7:54:36 LMG Uplock actuator begins to rise - 4 degrees/min - no report from crew or flight team
7:55:23 System 3 LH forward brake switch valve return line - rise 5 degrees/min
7:55:35 MLG left outboard wheel temp goes off line
7:56:20 Left upper wing skin temp goes off line - left lower wing skin temp goes off line
7:57:54 System 2 LH Aft brake switch valve return temp starts rise - 14 degrees/min
7:58:33 MLG left hand outboard tire pressure 1 goes off line
7:58:33 MLG left hand inboard tire pressure 1 goes off libe - getting near time contact is lost
7:58:35 MLG left hand inboard wheel temp goes off line
7:58:39 MLG left hand outboard tire pressure goes off line
7:58:39 MLG left hand inboard tire pressure goes off line

Remember all the wires connecting the actuators are in one bundle with the exception of the mid fuselage actuator.

[Budge]

No. But I may be misunderstanding what you mean exactly.

[XBob]

many thanks for the time line.

[Budge]

Why not put protective plates over the ceramic tiles ?

That thought crossed my mind too. Couldn't a protective cover be placed over the wings/underside then jettisoned along with the ET?

[XBob]

because you must still hoist the protection gear off the pad.

However, it might be a good idea to paint the tank, like they did the first tank. this only weighs about 400 lbs or so, and should protect the insulation more and hold it on better, and allow ice to slip off much sooner, and at a much slower speed.

[Budge]

No problem. If you would like to see and hear what Mr. D had to say as he showed them, check here. It runs a little over 10 minutes.

[XBob]

7 Feb 03 Dittemore told an afternoon briefing that a small portion of the reinforced carbon-carbon insulation of the leading edge of one of the Shuttle's wings was found in the Fort Worth, Texas area. It measures approximately 26-27 inches in length and 18 inches wide. It has not been determined whether it is from the left or right wing. The magnitude of the search for shuttle debris has expanded, with more than 1200 people involved in the recovery effort, including 220 from NASA and 800 National Guardsmen.