Posted on 02/05/2003 8:16:11 AM PST by TLBSHOW
Edited on 04/13/2004 1:40:21 AM PDT by Jim Robinson. [history]
On two previous flights, shuttle Columbia experienced re-entry problems similar to those that preceded its disastrous breakup Saturday, NASA records show.
In each case, damage to heat-shielding tiles on the shuttle's underside disrupted the flow of air under Columbia's wings earlier in the re-entry process than normal. That created excessive heat and stress on the damaged area.
(Excerpt) Read more at usatoday.com ...
Being in Arlington, Texas it was of ease for any of the local populace to see the breakup of the Shuttle IF they were inclined to be looking in the right direction at the right time. My sixteen year old boy was the only one in our family to see the break up.
The Shuttle over-flight was about 25 miles to our south. Given the height of 200'K and the horizontal distance, I would expect any sonic boom to be up to 2+ minutes after the fly-by. At the time, I was 3 miles east of my home and did not hear any sonic boom, let my wife did at home. Another friend 12 miles SE of our house heard a sonic boom. My son, whom was 6 miles east of our house and was outside did not hear a sonic boom yet saw the Shuttle.
Previous Shuttle over-flights did not create any felt sonic booms (house shaking also) and given that Shuttle debris has been found north and south of our house, was the sonic boom debris or the Shuttle itself?
Sonic booms should be correlation of the mass of the object. I have had rifle bullets fly just over my head on several occassions and only heard a "zing" and not a "crack" that others said should have been heard. So...give the sonic boom (house shaking boom), would one expect trash can size debris to be within one or two miles of my house?
I suspect that the three main shuttle engines caused the booms. Devoid of flammable materials and very heavy, they could have descended trailing relatively little flame in advance of the flimsier structures containing non-metallic materials. Traveling very fast through denser atmosphere they would have caused sonic booms. By tracking where booms were heard, it might be possible to locate the track that the engines were following. If they went far enough they might have reached the Gulf of Mexico.
When Mt. St. Helens erupted, there were basically concentric rings around the mountain in which the blast could be heard, and between which it could not be heard. This was because the sound would go up, bounce of a particular atmospheric layer, and then be directed back down to earth. Apparently this ricochet effect only occurred at certain angles with any efficiency (much like the way light only refracts in a prism or raindrop at certain angles), apparently having something to do with the way the air density changes at those layers. So it's just a guess that that's something like what you experienced.
An article posted here earlier mentioned that in the clinton years NASA changed over to a politically correct insulating foam, because the earlier foam contained Freon and offended environmentalists.
I'd be curious when the changeover occurred, how many flights have used the new foam, and in general what the experience has been with it.
I'd also be curious whether the new foam was more absortive of water than the earlier kind, since it's been said that there may have been a chunk of ice involved as well as the foam itself.
How large a mass is required for a felt sonic boom? How much does sound dissipate/diminish over distance?
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