Another freeper noted that the orientation of the insulation/ice object changes the impact force based upon the surface area of the impact. The individual made the observation that if the object had impacted "edge" on, the damage would be greater than if the object impacted flatly on the leading edge.
The white plume seen in this frame may be partly composed of silica particles from pulverized tiles. Given the substantial size of the plume when compared to the relatively small size of the object, one wonders if the plume size is actually the density and size one would expect from an insulation approximately 2 feet in diameter.
Once it is established that ET insulation alone can not create the plume seen (via the colorimetric test), it should be possible to create a second test scenario. A mixture of ice and ET insulation can be created to mimic estimated launch conditions. That mixture should be fired at the test article and the plume colorimetrics studied.
The resulting data could be compared to the photographic evidence and permit the composition of the plume to be evaluated in a scientific manner.
It is my contention that if one compares the plume from a 2' piece of ET insulation to the plume in the photo: 1. The photo has a plume with greater white tones 2. The photo has a plume in greater size than expected. 3. The differences in size of plume and tone are accounted for by silica pulverized by the impact.
Knowing hindsight is always 20/20, I welcome discussion and criticism. This posting is meant to contribute to the scientific process and only suggests one scientific method to approach the accident investigation.
Thanks... God bless and rest the crew of STS-107 and 51-L.
I wonder though, whether or if ice was invoved, would the plume not have some prismatic effect as light reflected off of it?
In all photos but that above point 4, the ET has a reddish-looking thing near the bottom of the picture. The highlighting does not occur in this area.
In the picture above point 4, where the highlighter does cover that area, the previously reddish-looking thing is now white, yet the plume does not appear to have extended far enough to have produced that white color.
I'm neither disputing nor defending the tile theory because I simply don't understand enough science to argue for one or the other. I'm just pointing out what I see :)
I have a slow connect to the web, so these are the first real close-ups I've seen. What type of camera/film are these images made with? It seems they are not 'normal' but are IR enhanced [much like 'night-vision' rectifiers] and therefor the colors would be warped. Having seen someone hit and sliced open with a less than 1/2inch slab of ice from a building, I think your synopsis is right on the money. Thank you.
SHUTTLE INFRARED LEESIDE TEMPERATURE SENSING
The SILTS experiment will obtain high-resolution infrared imagery of the upper (leeward) surface of the orbiter fuselage and left wing during atmospheric entry. This information will increase understanding of leeside aeroheating phenomena and will be used to design a less conservative thermal protection system.
SILTS provides the opportunity to obtain data under flight conditions for comparison with data obtained in ground-based facilities. Six primary components make up the SILTS experiment system:
(1) an infrared camera,
(2) infrared-transparent windows,
(3) a temper ature-reference surface,
(4) a data and control electronics module,
(5) a pressurized nitrogen module and (6) window protection plugs. These components are installed in a pod that is mounted atop the vertical stabilizer and capped at the leading edge by a hemispherical dome. (The SILTS pod replaces the top 24 inches of the vertical stabilizer.)
Within this dome, the infrared camera system is mounted in such a way that it rotates to view the orbiter leeside surfaces through either of two windows-one offering a view of the orbiter fuselage and the other a view of the left wing. The camera is sensitive to heat sources from 200 to 1,000 F.
The camera's indium-antimonide detector is cooled to cryogenic temperatures by a Joule-Thompson cryostat. The camera's field of view is 40 by 40 degrees. Its rotating prism system scans four 100-line fields each second, with a 4-1 interlace, resulting in a 400-line image.
Each of the two infrared-transparent window assemblies consists of dual silicone windows constrained within a carbon-phenolic window mount. The windows and window mount assemblies are designed to withstand the entry thermal environment to which they would be subjected without active cooling. They are, however, transpiration cooled with gaseous nitrogen during experiment operation so that they do not reach temperatures at which they would become significant radiators in the infrared. A small thermostatically controlled surface between the two window assemblies provides an in-flight temperature reference source for the infrared camera.
The pressurized nitrogen system comprises two 3,000-psi gaseous nitrogen bottles and all associated valves and plumbing. The pressure system supplies gaseous nitrogen to the cryostat for camera detector cooling, to the external window cavities for window transpiration cooling, and to pin pullers that initiate the ejection of the advanced flexible reusable surface insulation window protection plugs upon SILTS activation to expose the viewing ports and camera.
The information obtained by the camera is recorded on the OEX tape recorder. The data, when reduced and analyzed, will produce a thermal map of the viewed areas.
The SILTS experiment is initiated by the onboard computers approximately five minutes before entry interface, which occurs at an altitude of approximately 400,000 feet. The camera operates for approximately 18 minutes through the forward-facing window and left-facing window, alternating evenly between the two about every five seconds.
After the six planned SILTS missions, an analysis of structural loads will determine whether the SILTS pod should be removed and replaced with the original structure or remain in position for other uses. The pod thermal protection system is high-temperature reusable surface insulation black tiles, whose density is 22 pounds per cubic foot.
The hue of the dust was definately redish. I have no doubt.
NBC also verified the voracity of the reported tile loss over California. They said the guy was a astronomer with a telescope.
(I have the shuttle tile drawings in front of me as I type this. I haven't found my ET drawings yet. We boxed everything up when we left KSC...)
As far as the plume, I wonder if the size would be consistant with only the object being shattered. Personally I don't think so, but that is only MHO.
..... The interior of the tile is a white.....
It seems to me these statements are contradictory. Based on long ago upclose observations of the material, I thought it was white throughout with a black exterior surface.
If a tile sheared off as opposed to becoming unstuck, the exposed sheer surface would be white. If on impact the fragment disintegrated into a powdery cloud, the appearance would be light colored, in, fact would be reflective, and would be visable as a plume.
Similar visable phenomena would result from an ice blob so I can reach no conclusion.
More on Shuttle Foam Damage from STS-87
Monday, February 3, 2003
This NASA page has notes by a NASA worker from 1997 about the "significant damage" done to STS-87 from the reformulated, Freon-free foam insulation flaking off during the Shuttle's ascent (emphasis added),
During the STS-87 mission, there was a change made on the external tank. Because of NASA's goal to use environmentally friendly products, a new method of "foaming" the external tank had been used for this mission and the STS-86 mission. It is suspected that large amounts of foam separated from the external tank and impacted the orbiter. This caused significant damage to the protective tiles of the orbiter. Foam cause damage to a ceramic tile?! That seems unlikly, however, when that foam is combined with a flight velocity between speeds of MACH two to MACH four, it becomes a projectile with incredible damage potential. The big question? At what phase of the flight did it happen and what changes need to be made to correct this for future missions? I will explain the entire process.
And intriguing comments about similar issues during STS-86,
The STS-86 mission revealed a similar damage pattern but to a much lesser degree than STS-87. The STS-86 tile damage was accepted ruled as an unexplained anomaly because it was a night launch and did not provide the opportunity for the photographic evidence the STS-87 mission did. A review of the records of the STS-86 records revealed that a change to the type of foam was used on the external tank. This event is significant because the pattern of damage on this flight was similar to STS-87 but to a much lesser degree. The reason for the change in the type of foam is due to the desire of NASA to use "environmentally friendly" materials in the space program. Freon was used in the production of the previous foam. This method was eliminated in favor of foam that did not require freon for its production. MSFC is investigating the consideration that some characteristics of the new foam may not be known for the ascent environment.