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.
The piece the kid saw, was not in that category. It was large and illuminated the contrail. It appeared rectagular to me, but not sure.
I suggest we consider, though, that the port wing was rapidly breaking up at the end, starting with the leading edge and heading aft, and that the evidence of the gear box door opening, and the landing gear deploying, is better explained by the breakup reaching the gear box area.
"I was also trained in accident/loss investigation, to find the real original cause, and contributing causes."
The shuttle is launched with the tires uninflated, if I am not mistaken.
At what point in the re-entry process are they re-inflated, relative to the shuttle's re-entry timeline?
I am not clear if the tires had already been re-inflated when the loss occurred of vehicle.
Is it after falling below so many hundred thousand feet or 8-?
Does this process and its initiation ever vary?
What type of mechanism/mechinery is used and how is the process initiated, etc?
Any pyros involved in opening the wheel doors?
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Hot Plasma May Have Invaded Shuttle -Investigators ..
By Deborah Zabarenko
WASHINGTON (Reuters) - The extreme heat observed on the shuttle Columbia's left side during its fatal re-entry could have been caused by hot plasma penetrating the craft's wheel well, independent investigators said on Thursday.
 Reuters Photo Plasma is the super-heated gas that surrounded the shuttle as it streaked toward a landing at Kennedy Space Center (news - web sites) on Feb. 1. Plasma typically envelops a fast-descending space shuttle, but this time, preliminary analysis indicates it may have gotten inside the spacecraft's protective surface.
"Preliminary analysis by a NASA (news - web sites) working group this week indicates that the temperature indications seen in Columbia's left wheel well during entry would require the presence of plasma," the Columbia Accident Investigation Board said in a statement forwarded by NASA.
However, the board said the heat was so excessive that it could not have been caused by the absence of just one missing tile in the last minutes of flight.
This is significant since questions have centered on the possibility that some of Columbia's heat-shielding tiles were knocked off by a piece of foam insulation that fell off the shuttle's external fuel tank about 80 seconds after launch, apparently striking the left wing.
The board said investigators were looking at other ways the shuttle's skin might have been breached to let plasma into the wheel well area or elsewhere in the wing.
They also discounted fears that a problem with the landing gear on the left side of the spacecraft might have caused the shuttle to disintegrate over Texas, as a NASA engineer suggested in an e-mail two days before the shuttle's demise.
PROBLEMS ON COLUMBIA'S LEFT SIDE
"Other flight data including gear position indicators and drag information does not support the scenario of an early deployment of the left gear," the board said.
The board's statement was distributed by NASA, which has already come under criticism for failing to keep its distance from the independent inquiry that was appointed just hours after Columbia broke apart.
After a bruising four-hour congressional hearing on Wednesday with just one witness -- NASA Administrator Sean O'Keefe -- the space agency amended the investigative board's charter to address concerns about its independence.
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.
The data from sensitive devices that record infrasound, or low-frequency sound waves inaudible by humans, was sent to NASA, said Eugene Herrin, a geophysicist at Southern Methodist University in Dallas.
Herrin said data indicates a single explosion over Texas. A monitoring station in New Mexico showed the spacecraft as being intact as it passed over that state, he said.
Scientists operate a worldwide system of infrasound detectors that record items such as sonic booms. The devices look for any disturbance in the atmosphere such as a nuclear blast, meteor flights or even hurricanes.
Herrin said the infrasound likely recorded the moment when the shuttle blew apart, but the findings were preliminary.
The search on the ground shifted to Anderson County, west of Nacogdoches, where most of the reported shuttle debris fell. Officials said they have likely found more parts from the shuttle's wings and are checking serial numbers on recovered parts to see if they came from the left wing.
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Yes, that is the AZ video. I studied it, but could not save it, and my links do not work anymore either. I believe the footage has been zapped. Or the damn Real Player has crapped.
I checked the T.V. stations archive, and have not found it. My player refuses to play any of it anyway.
There are pyros on the latch that holds the wheel assy. in the up position. The door opens by a mechanical linkage which unlocks the door as the wheels begin to drop. No pyro on the door it'self.
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