[meteorite-list] Norway Meteorite Impact Site Believed to be Found

[Sterling K. Webb]

Hi, Doug,


    I still can't find the actual reference but it was a
paper by Aviva Brecher long ago. Oddly enough,
there's not much materials testing on meteorites
(maybe because it's destructive testing!), but
John S. Lewis reports on ten irons which yielded
crush strengths of 2.7 to 4.2 kiloBars (Gibeon was
3.2 kiloBars). This scarcely more than achondrites
(2.5 to 4.0 kiloBars). Wrought iron (or a mild
steel) measures 7.0 kiloBars. Cretaceous igneous
rocks from Greenland average 4.5 kiloBars, for
example. Terrestrial rock is stronger than iron
meteorites, in other words.

    Crushing strength of stone once very important.
Why is the Washington Monument the tallest stone
structure ever bult by man and probably the tallest
that ever can be built? You go up much further and
the load on the lowest trace of stones exceeds the
crushing strength of the stone. Bad news. You couldn't
built it out of iron meteorites -- too weak. Even so,
the other problem is that tall stone structures tend
to sink straight into the Earth because they exceed
the crushing strength of the crustal bedrock.
Whoops! That's why the Washington Monument
sits on a 140-foot cube of the hardest granite
known to man, which you never see, but which that
big stone plaza around the Washington Monument
is the top of!

    I love good engineering...


Sterling K. Webb
--------------------------------------------------
----- Original Message ----- 
From: <MexicoDoug at aol.com>
To: <sterling_k_webb at sbcglobal.net>
Cc: <meteorite-list at meteoritecentral.com>
Sent: Tuesday, June 13, 2006 12:04 PM
Subject: Re: [meteorite-list] Norway Meteorite Impact Site Believed to be 
Found


Hola Sterling,

>Turns out meteoric iron is often weaker than igneous
>rock while terrestrial iron is like, well...  like iron!

That is an interesting idea you have (and of course has nothing to do with
temperature).  On-the-surface, the crystalline structure giving rise  to the
Widmanstatten, and other figures, does seem like it could introduce  planes 
of
cleavage, especially when oxidation starts along the interfaces, but  as 
sexy
as a thought as that might be (and limiting to planar-'seeded'  fractures) 
I'll
definitely look forward to your posting on the issue not  have an opinion
until at least I read what you and that link have to say on this  subject 
subject
of iron meteorite brittleness.  What is ringing and  resonating in my ear as
I type this, though are thoughts of the Tucson Ring and  no shortage of 
other
meteoritic irons like Zacatecas (1969 )in history that have  be favored to 
be
used as anvils specifically for their superior properties vs.  other 
materials
when struck with a hammer.  Also the arduous chiseled  inscription on the
iron meteorite La Morita (apparently dating back to  at least 1821) comes to
mind: "Only God with His power --- this  iron shall destroy --- because in 
this
world there won't be --- another who  can undo it."  So field evidence and 
the
difficulty of even meteorite  hunters getting a piece of iron to take home 
as a
specimen might be at odds with  that...

OK, here's the link you asked for:
_http://www.diogenite.com/met-temp.html_
(http://www.diogenite.com/met-temp.html)

Remember the meteoroid shield failure (not due to a strike) of Skylab in 
the
mid 70's?  Here is another link for fun, related to the coldness of  space
(NOT) for those who forget we have a Sun in the neighborhood and why  skylab
could reach 165 deg C:

_http://history.nasa.gov/SP-4208/ch14.htm_
(http://history.nasa.gov/SP-4208/ch14.htm)
_http://history.nasa.gov/SP-4208/ch14.htm#t3_
(http://history.nasa.gov/SP-4208/ch14.htm#t3)
(actually all the links provide a great primer coat for thermal control in
space:-)

Extracted from the link text:  "The power shortage drew most attention  at 
an
evening press conference; little was said about an even more serious
problem, the apparent loss of the micrometeoroid shield. No one was 
particularly
worried about damage from a meteoroid strike, since the chances of a hit 
were
slim. i But the shield's secondary function, thermal control, loomed large 
in
the aftermath of the launch. The shield had been designed to keep the 
workshop
on the cool side of the comfort zone, heating being easier than cooling. The
outside of the shield was a black-and-white pattern designed to absorb the
desired amount of heat. The inside of the shield and the outside of the
workshop  were covered with gold foil, which regulated the flow of heat 
between the
two.  It was an admirable system as long as the shield stayed in place. 
Without
it,  the gold coating on the workshop would rapidly absorb excessive heat,
making the  interior uninhabitable.4

The shield had failed to deploy at the scheduled time and subsequent ground
commands had no effect. While officials were debating further action, Saturn
engineers discovered flight data indicating an anomalous lateral 
acceleration
about a minute after liftoff. The data, coming just before the space vehicle
reached its maximum dynamic pressure, suggested some structural failure. A
short  time later, workshop temperatures began rising, strong evidence that 
the
shield  was gone. Within a few hours, readings on many of the outside 
sensors
exceeded  82°C, the maximum scale reading. Internal temperatures moved above
38° C.  Working from the thermal model, Huntsville engineers figured that
workshop  temperatures would go as high as 77°C internally and 165°C on the
outside,  endangering food, film, perhaps even the structure itself. Mission 
Control
therefore began maneuvering the exposed area out of direct sunlight, and 
some
 cooling occurred.5

Saludos, Doug