Observation on TPS damage on Orbiter

NASA photos | 2-3-03 | BoneMccoy

[txradioguy]

Supposedly the have images from some of the spy satellites. I say it on Dridge, but have seen no follow up on it.


IMHO, the debate on whether the insulation could cause that kind of damage needs to factor in this tidbit. At the time the video of the insulation hitting the shuttle was taken, they were already at about Mach 2. The insulation is of a fairly rigid type too if what I've read is correct. If a tornado with winds of only 250 - 400 mph can drive a piece of broom straw through a tree trunk, wouldn't it be safe to say that a piece of rigid foam insulation at mach 2 could do some pretty significant damage?

[holden]

I'm a flight instructor and have seen ice form on numerous occasions. It gets your attention any time you suspect it's there.

Ice is definitely a fickle thing. You may have come through a lot of visible moisture on a flight with nothing but a light dusting, then, as you come in from the outer marker, whammo--it builds up as if it's trying to convince you there's no tomorrow.

Comment was made herein that someone was surprised that a chuck of ice wouldn't break up in the slipstream, as it was not "aerodynamic." Though I'm surprised how far down the ET ice was forming (or perhaps traveling--channeled down grooves?), one has to note that roughly half the shape of ice would be as a result of a structure that was designed to be at least somewhat aerodynamic, such that, if it presents itself to the relative wind and behaves as something other than an irregular mass in low-velocity turbulence, it should surprise no one.

Fickle as ice seems to be, it forms in areas where moisture is generally visible. That is, when the air temp meets or falls below the dew point. If the visible moisture is ice, it usually will be resistant to sticking (melting sufficiently then refreezing), but not always. So-called supercooled droplets which have some, presumably environmental reason for not crystalizing (impurity, micro-turbulence, ?), may all-too-readily "decide" they have an affinity for some passing by structure (whose surface temperature also tends to be below freezing).

In my limited(thankfully) first-hand experience with such phenomena, those structures which pose the greatest divergent angle to the relative wind are most prone to build-up, apparently because water molecules "linger longer" and can contribute to uncohesive airflow (turbulence). This is to say that ice seems to form most readily on those wetted areas which directly impact the relative wind. Ice formation farther removed from airflow diversion is unusual in my understanding.

Supposing it's ice I saw in the clips under discussion, it seemd to me the ice departed the ET fairly near to the shuttle's nose. That's unexpected! I wonder if the surface air pressure on the ET in such a vicinity is reduced by the aeodynamics of the shuttle itself. Could the shuttle's aerodynamics "help lift" ice from the ET body, through what must be a really high-speed, largely cohesive relative wind. The camera angles I've seen (and what little I could discern) tempt me to conjecture that the "ice" came toward the shuttle at its steepest angle immediately after leaving the ET (though my eyes could have been fooled), then the angle thereof decreased as it neared the shuttle body, only to impact near the port leading edge. To maintain such a divergent angle across a Mach One relative wind bespeaks one astoundingly large mass "launched" in that direction. Did it slide off some structure as if it were a ski jumper? If those suppositions are at least partly true, it could be that the configuration of the two main bodies and aerodynamics in those areas actually increase the possibility of being struck by ice, should ice be present. (note to self: check correlation of increased problems with winter weather.)

WRT channeling of ice along the surface of the ET, I'm led to wonder whether differential surface temps on the ET contribute to an uneven ice buildup or detachment likelihood.

Because of the latitude and proximity to moisture-bearing weather, potentially ice-laden Florida clouds are taller in the atmosphere than they would be elsewhere, as the troposphere goes to its greatest heights nearer the equator. Thus, a shuttle's lingering through such potentially ice-laden environment is greater than elsewhere, and such circumstances may be outside the ken of those trained in higher-latitude environments.

Translation: don't launch that the shuttle in the winter when clouds of any significance lie in its flight path.

HF

[spunkets]

Here's the dimentions of the ship. Using the videos in the link I posted and using the arrow key to single frame the 30 frame/sec video, I get from 120min to 270mph max for the chunk at impact. The video isn't that good for an easy tell. It must be massive or the relative velocity would be larger. It appears to be ice, exploding when it wacks the wing. Must be at least 5lbs. So at 150mph, it's at least 3500 ft-lbs. That's a significant hit. If someone plays with the video, they can get better numbers.

[Fabozz]

"This information will increase understanding of leeside aeroheating phenomena and will be used to design a less conservative thermal protection system."

Boy, in retrospect that's an unfortunate choice of words.

[Ichneumon]

The color of the object seems inconsistent with ET insulation.

Is the ET insulation orangish all the way through, or like the shuttle tiles, is it white inside with only a colored outer coating?

[Kahuna]

I don't know about satellite photo's, however I was on top of Haleakala yesterday and confirmed with a friend that the Air Force took photos of Columbia on the fifth day of the mission and has downloaded the images to NASA.

[jpsb]

Ok we have low temps, what about water? Was the launch preceded by rain?

[jpsb]

Both foam and shuttle were traveling at the same speed and in the same direction. It is delta in speed/direction that counts.

[DoughtyOne]

I conclude it probably wasn't ice. I say that because review of the video clearly shows a mass still in tact moving away amidst the debris after impact. This isn't clearly visible in the photos to my knowledge. Thank you for your comments regarding foot pounds etc. We'll just have to see how this plays out. Take care.

[ConservativeLawyer]

Bump for later read.

[Cold Heat]

ET insulation is orange/brown in color."

I saw someone in the know from Florida say that it is actually a light tan. The surface gets a bit darker as it sits in the sunlight due to reflected light. This person said the color looks differnt depending on light intensity.

My own experiences say that the colors are in the light tan to chaulky reddish/white range.

[demlosers]

BTTT Bump....read

[bonesmccoy]

That is precisely my point.

By doing the colorimetric analysis, you could evaluate the composition of the chunk that hit the orbiter.

[bonesmccoy]

Thanks for your compliment.

[bonesmccoy]

I've been reviewing your comments but do not quite understand what area you are referring to.

The photo is not from IR. The original footage is probably based upon long range film shot by one of the movie cameras which surround the launch pad.

Press correspondents should request release of all films of the launch from all KSC cameras.

[bonesmccoy]

I heard some of that press conference, but have not been able to locate the exact statement. Please quote exactly what the shuttle program manager noted or point to a transcript so that I can comment most accurately.

Thanks.

[Political Junkie Too]

Since the space between the fuel tank and the shuttle is constricted, wouldn't this cause the air to rush through it at an accelerated rate? Would that cause any object that fell into that channel to propel at an increased rate than otherwise?

-PJ

[bonesmccoy]

SILTS was never to be installed on the other orbiters. The reason is that it reduces the payload capability for station resupply missions.

I believe that the data acquisition is not real-time. I believe that the data is available after landing and recovery of the data storage device.

The media has been showing recovery of the forward fuselage and crew module remains. The widespread wreckage is consistent with inflight breakup of major structural elements at very high altitude. The location of the verticle stablizer debris is puzzling.

With all the pictures of various portions of structure, I've not seen any evidence of aft fuselage material.

If there are any Freepers in the Oklahoma, West Texas, New Mexico, or Arizona area, please post.

[bonesmccoy]

Great comments (when you're not bagging on OMDP in California)!

1. ET LH2
I think you may have missed my point. The plume color suggests that TPS silica was aerosolized by the impact. I don't believe that ET insulation would make a plume like the one observed on the launch replay film.

3. Landing gear door
Heating loads at the landing gear door are high. It has been known for many years that loss of TPS near the gear door would create potential for loss of vehicle. However, penetrations around the orbiter are plentiful. There are any number of different penetrations that have higher heating loads than others. I share your observation regarding the Main landing gear door's conspicuous location near the ice impact.

[bonesmccoy]

Yes, that is precisely my point. The plume appears too large to be from only ET insulation or only ice. The plume is larger because it may include a substantial amount of pulverized TPS.