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.
IIRC, the shuttle has to achieve about 17,000 MPH in order to orbit, and that speed through the atmopsphere should have generated at least some abnormal data, such as yaw correction or localized heating after the shuttle was damaged.
Another unintended consequence of govt politics.
Dependent upon the surface temperatures of the ET, one may need to look upon the entire structure as a moving, condenser-freezer which will inherently and actively generate copious quantities of ice.
Visible moisture is not an absolute requirement in the context of something, the surface temperature of which is far below the moisture-laden environment through which it flies.
I wonder what simulation models NASA has used to insure to itself that such predictable problems not cause its orbiters to be fatally compromised.
HF
The left landing gear door is that rectangular patch just at the inflection point of the wing. It looks close to where the plume appeared in the video, so the "door damage" theory seems plausible.
Note, BTW, that the video itself shows no obvious tile damage. This says two things:
1. The NASA folks who evaluated this made a reasonable decision.
2. The calls for ground cameras or sat-to-shuttle views wouldn't have seen anything.
The videos that NASA has are much clearer. What they posted are MPEGs that have much detail lost due to the compression scheme. They know the rocket's velocity relative to the air and an essential cross section of the object. They can get a very close estimate of the object's mass by it's deceleration in the airstream. If the object was very low density like foam, it would pick up a tremendous velocity in that ~1000mph airstream, because there is only a small mass and a very large cross sectional area to pick up momentum from the airstream.
The object in the film resists picking up velocity in that ~1000mph wind, that means it's massive. Also the explosive disintegration when the object impacted the wing manifests very high velocity dust particles extending out to a great distance. That means the dust particles themselves are quite massive. Very fine, light particle would never maintain that kind of velocity in air. They don't have the momentum to maintain significant relative velocity for any appreciable distance.
"The NASA engineers may have underestimated the size of the object."
They should have picked up on the essential features of what they were looking at right away. Seems that didn't have a hands on, or practicle appreciation, for what they were looking at.
" there is no way they could have repaired the damage or rescued the crew"
I don't believe that...
"unless the next flight was rushed to the pad and risked to save the crew"
and I don't think you do either.
They're going ~1000mph, ~mach 1.33.
" 2) Density Altitude
3) Are these terms from low-altitude aviation meaningful in near-space?
They're still in the atmosphere. The time of flight to that point was 81secs. They are not in near space.
In the background graph, the gird is 10" x 10" with the heavy divisions 50" apart.
Although the resolution of the photo evidence is not very good, a large area of damage as purported by some NASA engineers is not evident at all. In fact, no damage is evident. No gleaming white surfaces that would indicate damaged tiles.
I am now more than ever convinced that the foam hitting the wing is a red herring.
Again I believe that something not yet considered, was the catalyst for the failure of the craft. Their are so many possibilities that it boggles the mind but, we must figure it out and soon.
The media is putting up a statement that the 30 seconds of data could not be retrieved by NASA. They are wrong, that is not what NASA said. What they said was the data was too corrupted to make any sense.
The evidence then, must be on the ground. IMHO
I was looking at the drawings of the MLG system today, and noted that each gear door is held up by three hooks operated by a mechanical linkage system with push rods.
I was wondering whether the doors would open - or crack open - if one of those rods failed somehow.
Probably not, but the chances are good that we may never know what happened to Columbia.
I thought it might be slag, but then I wondered what a micrometeorite might look like or a piece of a larger one.
I have seen no more about it and found it interesting, to say the least.
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.
