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.
Has anyone found out what kinds of modifications were done to the RCC system at Palmdale?
Frankly, I'm amazed at the lack of interest here about what was done there.
Having some knowledge of troubleshooting, the first thing you should look at when something goes wrong is what you just changed.
It would seem that if the leading edge system was modified in some unknown (to me) way in 2000, and failed (in some unknown way) the second launch afterwards, that there should be at least a little curiosity here.
If you change the blowing agent and the solvents for the ET foam and it starts falling off in flight, then you have a pretty good idea that something is wrong with the new stuff.
When you change the RCC attachments and it starts falling off in flight....????
Excuse the levity, But Man! You are old!!!!!!
Excellent idea! And, this is the basis of systematic trouble shooting.
The mods are of great interest to me, but there is apparently no info available to the public, and no indication that they are pursuing this line of reasoning.
Did they do something to lighten this craft that would be suspect and/or cause the RCC to be different in some way? Did the take some inconel supports out that they felt un-necessary? Did they try something different with the tile thickness and arrangements?
Only the shadow knows for sure.
I have to check through my data, but I went to the schools site and got to the dept. site. The site was restricted, so that is all I got. If I recall, it was a astronomy dept.
This was the site, I do not recall the professors name, but his site was for students only. I believe the guy was the dept. head.
I noticed that OV-102 had a worm on the left aft payload bay.
Was the meatball logo on OV-102 installed during OMDP prior to STS-109?
The logo appears on the left wing upper surface.
The old worm was on the aft portion of the payload bay door.
I'm wondering if that NASA meatball logo was AFRSI. On prior flights the logo was a patchwork of blankets and LRSI white tiles.
This shows the vehicle prior to OMDP
This is a photo of OV-102 on STS-109 
If NASA is reading this, I hope they did testing on thermal absorption of the two designs.
The investigators have law inforcement searching western Neveda-southern Utah for an object tracked by radar...(FAA or Weather radar ?) It was reported snow on the ground hampered the search.
xBob, doesn't the discription of the damage to this piece of RCC sound familiar?
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