(meteorobs) Why do some meteors appear to zig-zag?
MexicoDoug at aol.com
MexicoDoug at aol.com
Fri Jul 9 21:58:06 EDT 2004
En un mensaje con fecha 07/09/2004 3:27:30 PM Mexico Daylight Time,
marco.langbroek at wanadoo.nl escribe:
> In the case of meteors during their visible meteor phase, you
> are talking of speeds at least tenfold that, and often (quite a lot) more.
> Even the slowest meteor has an initial speed of at least 11.2 km/s, and, in
> the case of surviving meteorites, extinguishes with speeds between 3 to 7
> km/s, and the latter speed values are reached only in the latest part of
Hola Marco, those are some very impressive statistics you present. You are
right when you say that we are comparing apples to pears in the case of Space
Shuttle Reentry and iron containing bolides. I made that clear, too, when I
brought it up: rather than compare I suggested just some consideration (which
has some, non-zero worth, in my opinion) as we focused a little more on the low
end of the energy spectrum. You discuss initial speeds of 11.2 km/s going as
low as 3 km/s at the ending of the pathways. For comparison, the Columbia
tragedy happened at 5.6 km/s, exactly half the initial speed you have quoted and
the normal navigation I mentioned happens at about twice the minimum you
mentioned - both within the range you accept for the "ending of the path".
In the tragedy, I am not ready to believe wind current is the only culprit of
scattering, and plenty of fragments did survive the macro "disintegration"
over an area I bet as large as France - at an altitude of the diameter of Paris
(Just speaking of order of magnitude loosely here, I don't remember the
"width" of the ellipse) Would you really expect the tiles traveling in the meteoroid
range of speeds that fell over near California to have followed smooth
arcs...and is that so bad an example as not worth considering?
I am still confused on one point, and that is: Of the over 1000 photo's
you've mentioned, none of which I have had a pleasure to see, not a single one was
recovered, according to your comments. Is it possible you and I are
discussing apples and oranges? You do mention that some are expected to have produced
meteorites. But that is a conjecture ...I do not dispute your frequencies you
imply, as I am not sure if the supposed slower speeds at the end of the
incandescent train can be I wonder, for example, if the Allende meteor(ite)
appeared to zigzag. It heavily sloughed (fragmented) and probably did not go out in
a single explosion I believe. Some pieces have primary fusion crust, others
secondary, others tertiary, and others none. Do you really think Allende came
in a nice arc like the meteor photos you have?
Finally, any information or graphs, or images or pdf's you might have would
be very interesting which you use to conclude that even toward the end of the
visible train of large probable meteorite producing bolides continue in a
straight line/arc. Also I would love to see some graphs relating mass, velocity,
and speed for a spherical blob entering the atmosphere at interesting angles,
to see its velocity profile vs. time, assuming a perfectly baked
(brazed...etc.) fusion crust at landing. That could help look for the limits for which
zigzagging might occur, if it does at all.
Thanks for your kind thoughts, also, still wondering if you really believe
in the objections for Pasamonte (motion, dust train only), but perhaps this is
viewed as to little a niche topic for this group which I am grateful to
benefit from, so I'll quit here, hoping you can address the real data and relevancy
question briefly. Saludos, Doug
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