[meteorite-list] Re: Meteorite-list Digest, Vol 26, Issue 30

From: Sterling K. Webb <sterling_k_webb_at_meteoritecentral.com>
Date: Sun Feb 12 23:11:31 2006
Message-ID: <002901c63053$8c24d240$7044e146_at_ATARIENGINE>

Steve, List,

    It's why I love tektites, as a puzzle.
Every theory explains some features;
no theory explains all the features of
those little devils.
    I regard them as still a wide open
mystery, the only scientific mystery
still going strong after more than 200
years of hypothesis. (The first tektite
theory was published in 1788, long
before the first scientific theory of
meteorites, which had not even been
accepted as real yet.)
    I keep a table of all the theories of
tektites, ancient and modern, and I have
39 listed, including the one that assays
that they are the gizzard stones of emus!
    There are several lunar theories. Nininger
(at one time) believed them to be Lunaites, or
ejecta from lunar meteoroid impact. Chapman
suggested that they were the material that
makes up the bright "rays" that a few young
lunar craters display, ejected all the way to the
Earth, thinking this would account for their
terrestrial distribution pattern (it doesn't).
    Lunar vulcanism of the ordinary
volcanic variety has been suggested
several times, the last time by John
O'Keefe, who refined it to a suggestion of
deep hydrogen volcanoes with hypersonic
hot gas plumes, before moving on to another
theory.
    I am not, BTW, denigrating O'Keefe
for changing theories in mid-stream. O'Keefe
put forward FIVE theories by my count, which
gives him more theories than any one else on
my list. He spent his not inconsiderable talents
on the problem, but all the theory buckets have
holes in them and leak like crazy, not just his,
but all of them.
    Today, we have the impact "consensus"
theory, which is actually not a consensus at
all, because every impact theorist of note
has a tektite impact origin theory of his own
which is not compatible with any other
impact theorist's tektite theory!
    But it's called a consensus because the
real consensus is that there is no point in
wasting any more time on tektites. We've
done them to death, performed every test;
it's time to move on and just accept the least
whacky answer by (unspoken) default.
    Don't get me started; I wrote that post
chewing over the impact theories a long
time ago... I even have a pet theory of
my own (I call him Bruno and feed him
regularly) that manages to explain a lot of
tektite puzzles that the other 39 theories
don't, but --- guess what? My pet theory
has different but glaringly obvious flaws
all its own, so it's DOA, just like all the
other tektite theories.
    They're a paradox. They're a problem.
They're like the jigsaw that seems to going
so well until somebody holds up a piece
you'd forgotten about and innocently says,
"Where's this go?"


Sterling K. Webb
------------------------------------------
----- Original Message -----
From: "Steve Schoner" <schoner_at_mybluelight.com>
To: <meteorite-list_at_meteoritecentral.com>
Sent: Sunday, February 12, 2006 2:41 PM
Subject: [meteorite-list] Re: Meteorite-list Digest, Vol 26, Issue 30


As Sterling Webb wrote, if the reasoning he posited follows then there is no
way that tectites came from the moon. The distribution on the earth, the
ablation shapes, stretch forms, and lack of cosmic ray exposure pretty much
eliminate the moon as the source.

Steve Schoner
IMCA #4470


Date: Sun, 12 Feb 2006 03:00:46 -0600
From: "Sterling K. Webb" <sterling_k_webb_at_sbcglobal.net>
Subject: Re: [meteorite-list] Orbital debris watching radar
To: <cynapse_at_charter.net>, "Meteorite List"
<meteorite-list_at_meteoritecentral.com>
Message-ID: <008e01c62fb2$d064d0f0$bb57e146_at_ATARIENGINE>
Content-Type: text/plain; format=flowed; charset="iso-8859-1";
reply-type=original

Hi, Darren,

    I gather from the phrase about having their orbits decay,
that by "Earth orbit," you mean "in orbit about the Earth."
Orbits around the Earth only "decay" because the orbit
touches the uppermost atmosphere enough to cause drag
which, however minute, reduces orbital velocity. It may seem
logical that materials kicked off the Moon would easily and
immediately end up in an orbit around the Earth, or at least
some of them would.

    But the truth is that it is nearly impossible to get from the
Moon to the Earth, and that lunar meteorites almost certainly
do not arrive at the Earth that way, however illogical that sounds.

    The many simulations of transfer of materials around the
solar system show the same result: impact materials from the
Moon mostly go into eccentric solar orbits. a small percentage
go into "co-orbits," that is, they enter solar orbits very similar
to the Earth's orbit, sort of wandering along with us, and it is
from that population that some get tangled up with the Earth's
gravity and get pulled in. "Short" transit times are 10,000 years.
When a lunar shows no cosmic ray exposure, that only means
that it was less than 25,000 years.

    The reason why it's so hard to get from the Moon to the Earth
is this: any object that falls to the Earth from a "great distance"
achieves escape velocity by the time it gets very near to the
Earth. And escape velocity is just that: you escape. No orbiting
for you...

   There is a point, between the Earth and the Moon where the
gravitational pull of the Earth and the Moon balance each other.
Since the Earth is heavier than the Moon that point is closer
to the Moon than the Earth. The point that lies in a straight line
between the Moon and the Earth is the first LaGrange Point,
BTW.

   But there are a multitude of points in every direction where
equal force vectors from the Moon and the Earth meet: a sheet
of zero gravitational potential.

    If an object is ejected from the Moon's surface toward the
Earth without enough velocity to reach the zero sheet, it falls
back toward the Moon.

    If it arrives at the zero sheet with just a smidge of velocity
more than zero, it will fall toward the Earth, ramping up to
escape velocity or near escape velocity at its closest approach
then roar on out into the solar system.

    If it arrives at the zero sheet with a good deal of velocity
more, it will fall on an Earth-influenced path and probably
ramp up to a lot more than escape velocity...

   So, you see, stranger, thar ain't no way to get thar from here...


Sterling K. Webb


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Received on Sun 12 Feb 2006 11:11:21 PM PST