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.
That would be the original .bmp. All the images posted are jpgs, with the artifacts that go with the handling. There's a lot that can be done , but it's all very tedious. The construction I posted above is very close. Locations, sizes, angles can be changed a few %, but it will be essentially the same.
As far as the telescope they used goes, I'm not sure which one they used and what wavelength they use to obtain it. They have the active optics to correct aberations from atmospheric effects, but this is close in. The tracking will be faster and so will the changes in atmospheric refraction they have to correct for. They may not want anyone to know how well they do yet, w/o having them do the work.
"where does the radar data indicating the object separating from the orbiter originate"
I don't know.
It confirms the left wing is going, and won't last for very much longer.
As to the details of the process, we just cannot see that. XBob's statement upon initial release of the photo that "the leading edge is now the MLG compartment" is as good of a assessment that has been made.
The questions and debate are all in the sequence of events prior to the picture. Therefore, little can be gained from analysis of this pic, other than the state of the wing at the time.
NASA is likely in the same boat with this image, no matter what the resolution is that they have.
7:52 a.m. CST: Three left main landing gear brakeline temperatures show an unusual rise. "This was the first occurrence of a significant thermal event in the left wheel well," Dittemore said. Engineers do not believe the left wheel well was breached, but rather that hot gasses were somehow finding a flow path within the wing to reach the wheel well.
7:53 a.m. CST: A fourth left brakeline strut temperature measurement rose significantly -- about 30-40 deg. in 5 min.
7:54 a.m. CST: With the orbiter over eastern California and western Nevada, the mid-fuselage mold line where the left wing meets the fuselage showed an unusual temperature rise. The 60F rise over 5 min. was not dramatic, but showed that something was heating the wing fuselage interface area at this time. Wing leading edge and belly temperatures were over 2,000F. While the outside fuselage wall was heating, the inside wall remained cool as normal.
7:55 a.m. CST: A fifth left main gear temperature sensor showed an unusual rise.
7:55.53 a.m. CST: A video image taken with this time stamp of Columbia showed a sizable brightly glowing object separate from the shuttle and fall back into it's wake. The object was too large to be a tile. These things had been seen before. No, it was much bigger than a tile. It could very well be the left side landing gear door. The kid who shot the video could be heard saying, "Did you see that?" "What was that?" (the object was bright enough to illuminate the contrail in the darkness.) It appeared to be rectangular, IMO.
7:57 a.m. CST: As Columbia was passing over Arizona and New Mexico, the orbiter's upper and lower left wing temperature sensors failed, probably indicating their lines had been cut. The orbiter was also rolling back to the left into about a 75-deg. left bank angle, again to dissipate energy and for navigation and guidance toward Runway 33 at Kennedy, then about 1,800 mi. away.
757:00 a.m. CST USAF photo is taken by telescope at the Starfire Range. It shows plasma burning and streaming debris from the left wing on the inboard leading edge going back over the wing resulting in a contrail.
7:58 a.m. CST: Still over New Mexico, the elevons began to move to adjust orbiter roll axis trim, indicating an increase in drag on the left side of the vehicle. That could be indicative of "rough tile or missing tile but we are not sure," Dittemore said. At the same time, the elevons were reacting to increased drag on the left side of the vehicle, the left main landing gear tire pressures and wheel temperature measurements failed. This was indicative of a loss of the sensor, not the explosion or failure of the left main gear tires, Dittemore believes. The sensors were lost in a staggered fashion.
7:59 a.m. CST: Additional elevon motion is commanded by the flight control system to counteract right side drag. The drag was trying to roll the vehicle to the left, while the flight control system was commanding the elevons to roll it back to the right. But the rate of left roll was beginning to overpower the elevons, so the control system fired two 870-lb. thrust right yaw thrusters to help maintain the proper flight path angle. The firing lasted 1.5 sec. and, along with the tire pressure data and elevon data, would have been noted by the pilots.
At about this time, the pilots made a short transmission that was clipped and essentially unintelligible
In Mission Control, astronaut Marine Lt. Col. Charles Hobaugh, the spacecraft communicator on reentry flight director Leroy Cain's team, radioed "Columbia we see your tire pressure [telemetry[ messages and we did not copy your last transmission."
One of the pilots then radioed "Roger," but appeared to be cut off in mid transmission by static. For a moment there was additional static and sounds similar to an open microphone on Columbia but no transmissions from the crew.
All data from the orbiter then stopped and the position plot display in Mission Control froze over Texas, although an additional 30 sec. of poor data may have been captured.
Controllers in Mission Control thought they were experiencing an unusual but non-critical data drop out. But they had also taken notice of the unusual buildup of sensor telemetry in the preceding few minutes.
About 3 min. after all data flow stopped, Hobaugh in mission control began transmitting in the blind to Columbia on the UHF backup radio system. "Columbia, Houston, UHF comm. check" he repeated every 15-30 sec., but to no avail. In central Texas, thousands of people at that moment were observing the orbiter break up at Mach 18.3 and 207,000 ft.
Milt Heflin, Chief of the Flight Director's office said he looked at the frozen data plots. "I and others stared at that for a long time because the tracking ended over Texas. It just stopped.
1231 posted on 02/10/2003 9:23 PM CST by wirestripper [ Post Reply | Private Reply | To 1217 | View Replies | Report Abuse ]
I plugged the USAF photo into the timeline I posted earlier. We have to assume the times are approximate, but within seconds due to timekeeping discrepencies that always exist.
IMO, this is precisely what I see as happening, via the timeline.
7:58 A.M. CST..........shuttle destroyed.
Going to bed now...........................
Again, one more attempt at clarity.
7:57 begin loosing control......
7:58 elevons not doing it, so thrusters assist.
7:59.......Shuttle yaws left and exposes right side to 3000 degrees.
Ditto that!
The camera buffs say the blue stuff is an aberration that affects the camera he used.
"1230 "Now that is useful: "... there seems to be a relatively unobstructed corridor in the wing adjacent to left side of main landing gear wheel well."
In addition, there is a zipper of tiles, just over this corridor.
By this I mean that there is an arrangement of tiles, one behind the other, just on either side of the wheel well which is unlike the other patterns, and would be prone to 'unzip'. the other tile areas are patterned to stop the 'zipper' effect.
The thingies, I agree, are likely tiles stripping. The location of the shot does not put those debris falling in California. This was the only point I was making on that.
These pics are not published, but it makes sense in the time line.
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