Q1:First he wanted to know if a meteor hits the moon is it technically
a meteorite or are only meteors that hit the earth called a meteorite? My
answer was that once a meteoroid hits a terrestrial body it is technically a
meteorite.
Q2: Second he wanted to know what if any changes would occur to a
meteorite once it is on the moon? He is very smart and understands that
weathering and a general erosion begins once a meteorite hits the earth due
to the actions of our atmosphere, wind and rain. He was wondering if it
were common place to go to the moon easily and find meteorites if they
would be pristine or would solar winds, and other impacts by space
dust, micro meteorites and the such erode them? And if the swings in
temperature extremes that can occur on the moon effect them in any way. My
answer was that they would probably change a bit over time, but the amount
of time that would be needed to cause any changes would be exponentially
greater than that of earth.
A2: Yes, Yes, and Yes. Chemical
recycling and weathering on the moon is much different and would be limited
to contact of finely pulverized powders and scant gasses liberated by past
volcanos/heating/, gasses,(i.e. sulfites, ammonia, O2, CO , and etc)
liberatedfrom meteorites etc. It just isn't a player in the alteration
of a meteorite. Appearance-wise there is no fusion crust -- but there may
mainly only be meteorite "powder". There is a strong possibility that
only the very largest meteorites exist in that collision forces converts the
bulk of the meteorites into dust and molten dropplets. Meteorite nodules
/shards are likely below the surface unless reexcavated by a subsequent
impact. The dust layer on the moon is the 99.99%result of impacts.See Bill
Arnet's site on the Moon
<http://seds.lpl.arizona.edu/nineplanets/nineplanets/luna.html>
and Nasa's Apollo Discovery Page
<http://www.nasm.edu/apollo/apollotop10.htm>Moon
Dust is composed of angular grains of various sizes and melted glass beads.
The dust appears to contain grains of both moon rock and meteorites
alike. There are several websites which have photos and descriptions of moon
dust. Both the Americans and Russians brought back dust samples. Solar wind
and Cosmic rays change the nature of the minerals on the surface. By in
large lunar soil is well mixed, churned, and not unlike howardites.
The heating cooling cycle on the moon is less destructive due to the
lack of water/ice. There is virtually "no heat/cool cycle" transport
down slope such as seen by freeze/ thaw on Earth. be it remembered also that
lunar rotation is 28� days so the heat/cool (expansion/retraction) cycle is
far more gradual than on earth..
Q3: The third question he
asked was since there is virtually no weather on the moon to stir up
dust and bury them meteorites would it be harder to find meteorites on the
moon? My answer was that since there is no atmosphere to slow their descent
that the impact speed would probably determine whether the meteorites would
end up buried deeper in the surface and it would also depend on whether or
not they would even survive the impact.
A3: No weather but
electrostatic forces induced by soalr winds may casue dust to migrate.
Seems like I recall some astronauts talking aboutt particles hovering above
the ground The dust cloud generated by an impact settles back over the
impact hole so there tends to be a blanket of dust on everything. It is
cumulative over time. When visiting one of the Surveyor Landers, Apollo
Astronauts found very little dust accumulated after 6-8 years, suggesting
that the blanket accumulates over eons instead of decades. Lunar gravity may
be weaker but it still causes the dust to settle. Moon quakes and
impact quakes apparently jar unstable slopes and reduce/flatten crater rims
as loose powder creeps downhill . Apollo 16 coring experiments found
that the dust/regolyth/soil level exceded 16ft( I think, the maximum length
of a core drill with them) The top 2-6 inches were less compacted than
further down. Talking to Charlie Duke Jr., Apollo 16 astronaut, and he said
they found trails where rocks and or meteorites had rolled and bounced along
the surface . I think he said they didn't see any at the end of their
trails. I believe he also said that they didn't find any meteorites on
that trip. So at least for the bulk of the ride around the rift,
meteorites aren't obliviously lying around the
surface.
Q4: last but not least he asked since the moon
is smaller than earth would the density/number of meteorites on the moon be
less than that of the earth? My answer was I would ask the experts on
this list. (I took the easy way out on that one!) I told him that without an
atmosphere to burn up any potential meteors that might hit the moon though
it was smaller more would make it to the surface than on earth, but that
without that same atmosphere to slow them down, many more would probably not
survive the impact and would end up pulverized to dust by the
impact.
A4: The fact that the Moon shields Earth from meteorites and
that Meteoroids burn up 99% of the time,
I would say there is more
unaltered meteoritic material on the moon I agree with you answer
Mark!
A bright mind Chris has...you've mentored him
well!
Regards,
Elton
