Observation on TPS damage on Orbiter

NASA photos | 2-3-03 | BoneMccoy

[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.

[Cold Heat]

You may be right. I thought the opposite of less conservative would be more liberal> LOL!

[Fitzcarraldo]

Excellent analysis! The way the solid object became a plume is significant. If that is shuttle tile pulverizing there was a real problem...

[small_l_libertarian]

I do see what might be a small plume before the large plume, but it may be a trick of sunlight. These photos are pretty dark, so it's hard to tell.

Fox News and MSNBC both have some very good video of this that they've been showing for the last two days. I will watch for the small plume and see if I can see it better in the video.

[AxelPaulsenJr]

Budge, what about the reports this morning that the trouble for the shuttle may have started a minute earlier thatn NASA had been saying? I heard they are now saying the trouble started at 8 minutes before the crash, not 7 as originally thought.

Where would the eight minute timeline put the shuttle over the earth as it was descending?

Thanks, Axel

[Budge]

Trick of sunlight...

That is why I was asking. I can't really tell.

I've only seen the video on FOX and assumed (silly me) that it was the same as the video FL Today has.

I honestly don't know about the small "plume" I see. But I thought it was worth bring up. Thanks.

[spunkets]

Here's a page from NASA with 3 mpegs of the debris hit. It looks like ice rather than foam, because the foam is too resilient to explode like that, larger frags leaving the impact area would be evident. If the ice weighted 1 lb and was going 300mph, it would have 6K ft-lbs of energy. Since it was bigger than pint size, I'm sure it had more. The ship was said to be going ~1000mph(mach 1.3) at this point. I also e-mailed NASA to get the frame rate of those flicks. If they answer, I'll post it.

[small_l_libertarian]

They may very well be using the same video, but what the news channels are showing is much clearer and brighter.

Maybe they just enhanced what they all have? (I have no idea how that works.)

[Starrgaizr]

"the object is tumbling"

the object is accelerating, relative to the Orbiter. The Orbiter is at maximum acceleration UP and the object is rapidly deccelerating as it is not aerodynamic and it is tumbling.

Also, how massive must a piece of ice be to withstand the relative wind as an intact piece of ice rather than be smashed to smithereens by the "slipstream" prior to impacting the wing?

The latter suggests at least some insulation, no? Would ice hold together? If so, it would have to be more than a thin, low-mass sheet.

[Budge]

Budge, what about the reports this morning that the trouble for the shuttle may have started a minute earlier thatn NASA had been saying?

I don't know, and can't confirm just when the trouble started.

NASA is reviewing the tape from the Australian astronomer in California that he took as it was passing over. It clearly shows something comming off Cloumbia then. That alone would put the beginning of trouble earlier.

Then there is the video the two young men took as it passed over Nevada. It clearly shows something comming off. They even comment on it on the tape. What I have no idea is, is that he same pice that the fellow in California saw and photographed, or another piece.

As far as your origional question of the time line, it will take someone much smarter than I to determine just that put Columbia. I'm thinking in the California/Nevada area though. Perhaps Snooperpod or bonesmccoy can better answer.

[elfman2]

I agree

[montag813]

Ron Dettemore mentioned the color during his press conference yesterday. He noted that the color could be called light rather than white. I got the impression he was stalling and playing rope-a-dope. He knows the color is significant just like you've noted, and one day he's going to be held accountable.

He should get 10 years in a Federal, "pound-me-in-the-a**" prison.

[Budge]

CORRECTION to my post #49.

Then there is the video the two young men took as it passed over Nevada.

That should be Arizona, not Nevada. They were in Wupatki National Monument (NE of Flagstaff) in northern Arizona.

The video, along with a still shot can be seen here.

[jpsb]

Ice requires low temps, what was the temps leading up to lanuch time?

[ContemptofCourt]

Ice forms on the ET because it is liquid-nitrogen cooled....also, the ET shrinks up to 6" at launch due to the cooling.

[ironman]

"NASA yesterday also released its engineers' initial analyses of the damage that might have been done to the shuttle's protective tiles when a piece of foam apparently broke free from its external tank during launch on Jan. 16.

The analyses, which were worked out while the shuttle was in orbit, included one hypothetical worst-case scenario involving a piece of foam 20 by 16 by 6 inches and weighing 2.67 pounds hitting the underside of a shuttle wing. That analysis estimated there could be "tiles missing over an area of about 7 in. by 30 in." It also predicted that even though there might be "localized heating, with some effect on the basic structure in that area, you would not have damage sufficient to cause a catastrophic event" or even affect the vehicle's flight capabilities, Dittemore said. The engineers' conclusion was that the scenario posed "no safety of flight issue."
http://www.washingtonpost.com/wp-dyn/articles/A21208-2003Feb3.html

[dfwgator]

Aren't there satellites that could have taken pictures of the shuttle as it was re-entering Earth in order to get a better idea of really happened?

[Budge]

Good find.

[Stefan Stackhouse]

I can imagine an alternative design for a smaller "space plane" designed to carry human payloads only. This smaller vehicle would be mated to a "service module" somewhat similar to that of the Apollo, containing engine, fuel tanks, and perhaps O2, H2O, and fuel cell tanks for in-flight supply, all of which would be jettisoned immediately after the re-entry burn. It would include enough fuel on each mission to assure that the spacecraft could make it to the ISS, and perhaps a rendezvous with the ISS should even be a routine feature of all missions, allowing the ISS crew to do a visual inspection of all tile surfaces.

This assembly in turn would sit atop one or a cluster of solid fuel boosters. Such a design would mean that there would be NO external fuel tank, and nothing adjacent to or above the orbiter as it was ascending -- thus nothing that could break off and damage the tiles. Such a design would vastly improve the safety of the tile system and drive down the risks of catastrophic failure to more acceptable levels.

Your thoughts?

[Atlas Sneezed]

"This plume has a white color. Unfortunately, ET insulation is orange/brown in color."

Good analysis, except that I am doubtful about the certainty of the above. Colored things can look white (and I see redness in the picture) when pulverized and illuminated brightly.

[Alamo-Girl]

Thanks for the heads up!