Posted on 02/04/2003 1:34:19 AM PST by 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.
You've got some strong comments regarding numbers, but nothing to back them up. If you have a problem with any of it, be specific.
I guess the without warning aspect is what I speak to.
I find it very interesting that some evidence points to wing deformity, per the military telescope at the observatory in NM.
The Fox video capture of the shuttle where it zooms in, shows the shuttle's position to be off course (relative wind / angle of attack) by 90 degrees. The ship is wings level, traveling sideways with the nose facing south. How long it had been in that position (by then) is unknown, but at 12-15,000 mph, it's not likely to remain intact for much longer (than the time of video capture / exposure).
I'll take another look at the time line.
25,400 fps is more accurate... ;-)
I have a dell laptop, so I can tilt the screen to get a 3-part 3-d view if I combine them in my head so they layer.
I see the chunk of insulation strike edge on, slightly left(maybe a foot or less) of the point where the wing flares to the front and directly behind the leading edge(maybe 6 inches), of the wing. It appeared to hit right on the line between the black edge and the tiles.
In short, looks like it hit the first row.
As before, when I saw the video on TV, I cannot see any change in hue or a mark of any kind.
Is it possible that the impact damaged the first tile that mates with the leading edge and allowed plasma to flow into the void and burn out the hole until it broke through underneath the leading edge?
This is the only way I can figure the tile impact may have damage the wing enough to cause a eventual loss of the craft.
The impact point that I picked, is a tile directly behind the leading edge and it adjoins a border of something that surrounds the left wheel cover.
What would serious damage to the one tile behind the leading edge do to the wheel well integrity, gasket or seal?
Something certainly seems to be going on, but what?
Will try, John.
I will send a copy of the tile diagram to Budge and he can post it to see. I marked the place where I believe the object hit. It was edge, or actually corner first into the wing.
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