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.
A chunk of styro foam would certainly cause no structural damage like dislodging the locking pin or what ever, so what did happen?
It could be as simple as the possibility that the door was not latched.
NASA has by it's own words, eliminated the ice theory. (they would know, because the crew viewed the tank on separation and likely saw the missing piece)
I am still looking for the cause. I cannot satisfy myself with the foam theory and neither can NASA.
"I read a study of the turbulence in the area between the shuttle and the tank, a few years back. and remember that the turbulence in this portion of the stream is very high. I don't remember the relative wind information, but do remember that near the nose it is very slow."
Yes the area between the tank and the obiter would have quite a bit of turbulence, becuse of the high reynolds number there. The area around the nose would be where the shock front is generated, in front of the nose would be effected as the streamlines from the tank and boosters would develope there.
The debris itself is riding the streamlines, except where it bumps the shock cone. It's being accelerated away from the tank, until it encounters the streamlines developed by the obiter, there it's slowed in the radial direction, so it passes under and wacks the underside of the wing.
Nope. Out looking for a job today. I'm finding out that there is no market for ex-shuttle engineers in the Carolinas...
There are (IIRC) 14 vent doors along the sides of the orbiter to accomplish that task. Frankly I never knew via what path the air in the wings and wheel wells got vented. I assume into the midbody then out the vent doors.
If the vent path for the LMG wheel well got plugged, I'm guessing it might blow out the bulb seal around the door perimeter.
At least we FReepers are ON THE PROBLEM!
Keep the faith! What is your forte? Mechanical or Electrical?
It could explain the head transference to the side wall I/R sensors, but the crack would be covered with refractor tiles, would it not?
Think of the bulb-seal around the landing gear door perimiter as weatherstripping. My memory of the stuff is fading, but I think it was kind of fuzzy looking from the outside. In cross section, it was round so as to fill the gap and expand and contract with movement.
The temp sensors around the shuttle were simple thermocouples, not IR sensors.
Your resume should be of interest to many in the construction industry. This is where I came from.
Brown&Root, (I hated them)Fluor, or Fluor Daniel, (I loved them) Shell oil, (not bad) and or Marathon, Borden, and a slew of others. Bridge outfits as well. I am also multi craft and never went without a check for more than a month. I currently hail as a retired master electrician, but can work as a millwright or whatever I please.
You will have to take a wack in pay from the Goobermint jobs, unless your get in with big time references or a fast track promotion setup.
The important thing, is to do what excites you and makes you take your work home with you, despite your females objections...........LOL!
Yep, and our Marines can't practice realistic landings on the Camp Pendleton beaches because of the danger to "fauna" and some "plover" bird. Damn stupidity that boggles the mind.
What a joke they are!
The fact that the shuttle began loosing tiles over California, and some bigger parts over Nevada and arizona, lead me to believe the damage was not minor dents, but serious damage and or a failure of some sort.
Could be a mechanical failure, a space debris strike, a meteorite or some other thing that had zilch to do with the tank.
Still looking and unconvinced.
You never know where a thread will go.
5.56mm
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.