Moon rocks, dust and lunar meteorites

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Moon rocks, dust and lunar meteorites
Key Features of the Moon pages 156 - 164 and
172 - 192
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Physical parameters for the Moon



1/6th the Earths


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Why study the Moon?

• The Moon is ancient and preserves an early
  history (the first billion years) that is common
  to all terrestrial planets.
• Active geologic forces, including plate tectonics
  and erosion, continuously destroy the oldest
  surfaces on Earth, whereas old surfaces persist
  with little disturbance on the Moon.
• Provides a key for unraveling time scales for the
  geologic evolution of Mercury, Venus, and Mars
  based on their individual crater records.
• Photogeologic interpretation of other planets is
  based largely on lessons learned from the Moon.

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The Moons face

• The highlands (terra) are brighter and have more
  craters than maria (pl mare).
• What caused these differences?

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Topography of the Moon
S. Pole/Aitkin Basin
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The types of soil and rock on the Moon
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Mare soil (regolith)
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The astronauts footprint in the lunar soil
(regolith) will last for millions of years, until
wiped out by impacts of meteoroids from space.
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This lunar soil, recovered by Apollo 11 from Mare
Tranquillitatis, was cleaned with acetone to
remove ultra-fine dust. It consists of
impact-produced glass spheres lt 1 mm in diameter,
brown pyroxene (an Fe,Mg silicate), white
anorthite (a calcium-aluminum silicate), and
various rock fragments.
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Mare basalts

• Maria
• Dark
• Low in aluminum
• High in iron
• Poor in plagioclase
• High in pyroxene olivine
• Exhibit younger isotopic dates (4.1-3.1 Ga)
• Have fewer craters

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Thin section photomicrograph in transmitted
polarized light of an Apollo 15 fine-grained
pyroxene-phyric mare basalt
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Thin section photomicrograph in transmitted
polarized light of an Apollo 15 Medium-grained
pyroxene-phyric mare basalt
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Thin section photomicrograph in transmitted
polarized light of an Apollo 15 Coarse-grained
pyroxene-phyric mare basalt
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Explosive volcanism Fire fountaining at Puu
Oo, Hawaii, on June 2, 1986.
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The famous orange soil glass spheres from the
Apollo 17 landing site. They are thought to have
formed by explosive volcanism (fire fountaining).
The spheres are lt 1mm in size.
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Thin section photomicrograph in polarized light
of a crystallized sphere of the famous green
glass that is also thought to have formed by
explosive volcanism (fire fountaining).
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Highlands Crust

• Highlands
• Bright
• High in aluminum
• Low in iron
• Rich in plagioclase
• Low in pyroxene olivine
• Exhibit old isotopic dates (4.3-4.1 Ga)
• Have lots of craters

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A highlands breccia from the Apollo 16 landing
site, consisting of comminuted anorthositic rocks.
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Photomicrograph in transmitted light of one of
the few unadulterated, pristine igneous rocks
from the lunar highlands, a spinel troctolite.
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Photomicrograph in transmitted polarized light
of one of the few unadulterated, pristine igneous
rocks from the lunar highlands, a spinel
troctolite.
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Search on the blue ice of Antarctica for
meteorites, including those ejected by impacts
from the Moon
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Discovery on the blue ice of Antarctica of
large numbers of meteorites, including some
ejected by impacts from the Moon.
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Antarctica is the best place to find meteorites
on Earth, because the ice preserves them for 106
years, and because the movement of ice
concentrates meteorites in areas of blue ice!
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Flow of ice from center of Antarctica to the
coast concentrates meteorites up-slope from
mountains
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Cross-section through the ice cap in Antarctica
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The first lunar meteorite ever recovered on Earth!
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Thin section photograph of the first lunar
meteorite recovered on Earth, ALHA 81005, a lunar
regolith breccia ( 2mm in diameter).
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For comparison, this is a photograph of an Apollo
14 regolith breccia, which clearly shows the
similarity in texture to the lunar meteorite,
ALHA 81005.
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The abundances of certain chemical elements (here
La and K) in rocks are finger prints for their
origin on a particular planet. Shergottites,
nakhlites, chassignites Mars Eucrites,
howardites asteroid Vesta. ALHA 81005 clearly
plots with analyses of Apollo Moon rocks!!!
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The value of the 30 known lunar meteorites is
that they, most likely, do not come from the
sites were the Apollo missions landed. Thus, they
provide us with rocks from new, previously not
visited sites on the Moon.
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Ice at the Poles
1 - 10
20 - 30
50 - 60
60 - 70
time in shadows at S. Pole region
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Ice at the Poles from neutron data