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(meteorobs) TWA800 and meteors
I almost hate to jump in here, since myself and Dr. Meisel have both had
some unpleasant e-mail from Mr. Davias over this matter. Davias seems to
think that if you don't jump on his bandwagon, you're hiding from the facts.
I don't profess to know everything, and for the record I think it is indeed
possible that a meteor hit TWA800, I just think it's very VERY unlikely.
What I want to do in this post is correct a few of Mr. Mielke's blanket
statements. The internet is rife with bad science and worse information,
and inaccuracies must be pointed out and corrected.
>Group:
>I am becoming more involved in the TWA Flt 800 accident.
>According to USA Today The Boeing Company cannot even take a photo of the
>mocked up aircraft.
It would seem a lot of others can, and have, and have published the results.
There was a two page spread in U.S. News or Newsweek in the last month or
two showing the right side of the aircraft. There have been others in
Aviation Week.
>
>The fuel tank explosion was quickly discounted by TWA retired engineering and
>maintenance personnel. The most common remark was that there was no source of
>ignition.
Quoting from USA Today's web site:
"Bad wiring on fuel pumps caused arcing and a fire on a 747 that was in a
maintenance hanger in May 1995. Since then, Boeing asked airlines to check
all 14 pumps on each 747. The wiring was bad on 7%; eight were leaking fuel.
Repairs were made."
And an interesting, similar case:
"11.05.90 () Boeing 737-3Y0
EI-BZG (24466/1771) Philippine Air Lines
Crew: 0(6) + Pax: 8(113) = 8(119) +
Manila (Philippinesd) GR
SP Flight from Manila IAP to
A powerful explosion in the center fuel tank pushed the cabin floor
violently upwards, while the aircraft was being pushed back for a flight to
Iloilo. The wingtanks ruptured, causing the Boeing to burst into flames. The
center fuel tank was empty at the time, except for some fuel vapours. The
vapours ignited probably due to damaged wiring, because no bomb, incendiary
device or detonator
has been found."
"Source: IATA 1990 total losses list"
I personally recall a B-52 accident at K.I. Sawyer AFB in '87 or '88 in
which a fuel pump overheated, and detonated an empty wing tank. This stuff
does indeed happen.
>With experts carefully analyzing these streaks of light it was possible to
>determine the path of a meteor. Experts could then determine its size, speed
>and its flight path.
Which experts? And this was published where?
>When meteors enter the earth atmosphere the speed of some is approximately
>Mach 4 ( four times the speed of sound).
The speed of meteoroids entering the earth's atmosphere is between 11 and 72
kilometers per second, or mach 32 to mach 210!
>At this speed the force of air pressure on the meteor could be about 200
g's, a >force great enough to shatter the meteor.
"g" is a measure of acceleration, not pressure. Deceleration of a recent
fireball (Note 1) that entered the atmosphere at 15 km/sec averaged about
2,900 m/s^2 -- approaching 300 g's.
A meteoroid at 16 km altitude moving 11 km/sec would be subjected to 1,375
psi of pressure (Note 2).
>This point is referred to as the bolide.
A brilliant meteor is called a fireball. One that explodes is called a
bolide. A bolide is not a point on the path of a meteor.
>is estimated the bolide occurred at an altitude of approximately 9 miles
>which was approximately six miles above and 10 miles southwest of the
>aircraft.
So in order to strike the aircraft, a fragment would have had to travel 11.6
miles on an angle of 33.5 degrees from the horizontal. Bolides very rapidly
lose the balance of their speed after fragmentation and descend steeply to
earth on a ballistic path. The earth point in your scenario, a line drawn
from the fragmentation point through the aircraft would intersect the
surface at 16.3 miles from the sub-fragmentation point. Fragments from a
bolide that entered on a slightly shallower angle (22 degrees) in 1984, and
that detonated at a slightly higher altitude (16 miles) were estimated to
have travelled half the distance to the earth point (Note 3). Apply that as
a thumb rule to your bolide, and you come up with a surface impact point a
little more than 8 miles from the sub-fragmentation point. A little short,
but I'll give you that that would be the center of a dispersion ellipse, and
some fragments could fly farther.
>This fragmentation delivers a spray of objects, one or several
>could have hit the aircraft. Other fragments may have landed in the water
>closer to the Long Island shore and in more shallow water.
I don't think too many would have gone closer, see above.
>The sonic booms heard on shore were caused by these fragments.
IF it were a bolide, the first sound witnesses in the area would have heard
would have been the detonation, many seconds after the event. Then perhaps
sonic booms or a rumble as the sound from further back up the path of the
thing caught up. The fragments would have rapidly decerated to a sub-sonic
terminal velocity, creating no boom.
>While the theory of a meteor hitting an aircraft is incomprehensible to most
>people,
You insult us. It is not "incomprehensible" to the literate folks here.
Some of us just consider it highly unlikely. Thanks to Jim Richardson for
the following:
"Question:
What are the chances that a meteor will strike a 747 sized aircraft?
Answer:
A reasonable estimate is that about 30 meteorite events in the kilogram
range strike the earth each day, giving:
30 meteor / earth * day
converting to square meters of surface area gives:
1 meteor / 1.70e13 m^2 * day
Assuming that a TWA 747 presents about 2000 m^2 of surface area:
1 meteor / 8.50e9 TWA * day
In other words, the chances of a 747 being hit by a meteor during the
course of a day is about 1 in 8.5 billion.
In any given second, this is 1 in 7.34e14 (734 trillion).
Another way to look at this is that 1 747 will be hit about once every 23
million years.
Pretty unlikely, unless there was overwhelming evidence to support it."
>A 27 lb meteorite hit and destroyed a car of two 18 year old youths in
>Peekskill, NY on October 9, 1993. They sold the meteor for $69,000.
Destroyed? I have a picture of the car in front of me. It's certainly not
destroyed; it looks quite driveable. There's certainly a big hole in the
right rear of the trunk, and a fair bit of bent sheetmetal, though. The car
is reported to have sold for $10,000!
Please get the facts straight when you go to publish such material.
Note 1 -- Bolide AIDA: Death of an Aubrite Meteoroid, D.D. Meisel, V.S.
Getman, J.D. Mathews, S.C.Jacobs, and R.G. Roper 1995, Icarus, 116, 227-254
Note 2 -- Rocks from Space, O. Richard Norton, p. 69. Mountain Press
Publishing Co. 1994
Note 3 -- Fireball of 8 January 1984, P. H. Andersen, I. D. Cameron, D.
Weinrich, American Meteor Society Annual Report 1986
Jim Bedient
American Meteor Society
Electronic Information Coordinator
Honolulu, Hawaii