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.
In this hypothetical scenario, someone could have reasoned, hey, let's institute a backup plan: A. a way to investigate in-orbit for TPS damage; B. in the event of critical TPS damage, a way to get extra "expendables" (air, water, station-keeping propellant) to shuttle via unmanned backup system; C. a stopgap TPS patching solution; D. a backup way to get the crew home.
Yes, I know that the engineering challenges would be steep. However, few will dispute that NASA employs some really bright people. Instead of hobbling them with regulations and restrictions, what if some one had turned loose a mitigation "tiger team" of 50-200 really smart "rocket scientists" and engineers? I would be willing to venture that during 5 years such a team could have come up with a backup plan that would have some non-zero probability of success.
That NASA knew the foam was shedding, and damaging TPS tiles, has been documented elsewhere. That NASA knew that the loss of a single critical tile could result in burnthrough, and mission loss, is documented elsewhere. That NASA had no backup plan, no mitigation, is documented elsewhere (they stated this openly on the day of the disaster). This is profundly sad. I doubt very much that the NASA of Werner von Braun's time would have had no solutions to offer.
In all the graphics posted here I have yet to see the opening in the wing where the strut rod that attaches the shuttle to the ET mounts to the air frame. This is important because Dittemore mentioned it in day one briefing that the foam may have hit the fairing around the strut and damaged it.
We studied the impact days ago. What we found was that the foam impacted in the gear door area, perhaps the front of it.
The appearance of the cloud exiting the wing in the way it did, is explained by the angle that the foam came from. It came from the forward mount which is located forward and center of the orbiter.
If you draw a line between the points, it seems to line up with the angle of exit. Also, the dust was accelerating much faster than the foam piece and seemed to exit almost into the camera direction. Again, those angles correlated to the path of the foam.
The search for debris from Columbia continued in Texas, where a preliminary analysis of low-frequency sound wave recordings indicated the shuttle exploded between the cities of Amarilla and Lubbock, about 330 miles west of Dallas.
A certain irony to his death occurring so close to his home town...
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