2 SESSION 2
Anorthosite
Large crystals
(asteroids and comets don’t have large amounts of anorthosite)
Large crystals have cooled slowly—are intrusive rocks
Largely accepted but still testing the idea that . . .
Basalt 3 billion years—younger
Flood basalt up out of the ground: Blue areas on the map—they are lower
Data suggests early in development of Solar System there were large items flying
around which left VERY large holes in planetary objects
Asteroid (size of Baltimore or larger) slams into the Moon will make a hole 10 X
larger throw out crust, crack crust with molten lava later . . .
Basalt may have escaped through the cracks
Dunite in the deep crater areas
Older rock
Spew out
Olivine/dunite under crust
Earth is mainly olivine deeper down (mantle)—can expect the same on the Moon
Make POSTERS about their ideas of what the rock location means—then present
their theories to each other
On Earth from deep explosive eruptions are deep green olivine
Green beach in Hawaii—pulverized olivine.
May be still molten
Mantle is plastic but SOLID rock being deformed slowly under the pressure—moves
at the rate that fingernails grow.
Outer core of Earth is liquid
All hot enough to be liquid—the high pressure keeps mantle as a solid
The outer core is a liquid. Why?
Earth
Crust
Mantle
Outer core
Inner core
Hotter
inside
Crater = indent
Don’t need impact for crater
Originally thought that the Moon craters were from volcanoes
Didn’t know until they went to the moon that the craters were formed from
impacts
A lot of rocks are breccias—bits and pieces lumped together angular—
confirmed impacts—metamorphosed by the impacts
Reflection data from Altas
Moon mineralogy Mapper—inquiry activity
Inquiry science
Asking questions (can be unstructured where the students come up with the
questions
Structured inquiry OR OPEN inquiry—but instructor asking the question or
piquing their interest.
OR start with questions and direct the students to develop more questions
“looking into”
Student led—no teacher guides
What do teachers do? Activity
Didactic, chalk and talk, traditional
There are times when it’s appropriate
Students will lose interest and no independent thinking
Will not retain it full time
Will misconceptions be changed with teacher-led statements?
No serious misconceptions dispelled.
Students don’t necessarily hear what is said.
Dr Jim Rice
Goddard
Working with Moon and Mars
Lunar Reconnaissance Orbiter, LRO
Origin and Geologic History of the Moon
Mars Rover Science Team
1955 Cecil Bannister
First space artist
Magma and early Earth, meteorites and Moon closer
Man in the Moon
15th century Norfolk church of St Mary
From mother goose nursery rhyme
Made of green cheese
1546 John Heywood proverbs (haste makes waste)
Green cheese is not the color it’s unripened
1968 mission round Moon Grissom what’s the Moon made of—“American
cheese”
Near side with landing sites
Large crater Tycho
Topography—not smooth
Flat areas –maria—flat basaltic seas
Back side is much more battered—more crater impacts, etc.
Highlands—heavily cratered
Mare serenitas
With wrinkle ridges. Info from LRO
6 Apollo missions, 12 landed on the Moon
6 locations mostly equatorial
Like visiting 6 places in Africa and thinking you know the whole continents
650 lb
some unopened for future technology
Russian’s brought back few oz
N plate tectonics on moon
Lunar interior—core solid
Crust Silicate, mantle silicate, core . . .
Iron/Ni in Earth molten and rotating forming magnetic fields
How did the Moon form
NOT
3.3 g/cm3
earth 5.5 g/cm3
Moon depleted in Fe, water, volatile elements—gases and l
Recently explosion on Moon to disturb materials
No oceans
Moon enriched in Ca, Al, Ti, all refractory elements-condense at hight T
Moon and earth have same isotopic compositions for several elements, O, W
(no 2 planet’s atmospheres are the same isotopic composition)
Physics constraints
Outer part molten in history
Mass ratio the largest in the Solar System Double planet system?
Mars 10-15 miles long axis and irregular shape like potato
Angular momentum equivalent to an original rotation period of 5 hours
Was closer to Earth
CAPTURE Model NOT TRUE—difficult to explain how velocity allowed orbit
capture
Explains differences in chemistry
Hard to dissipate energy to enter orbit
Does not explain isotopic similarities
FISSION model
NO
Angular momentum 2 x too small
Should orbit at equator
BINARY ACCRETION
NO
Explain isotope
Does not explain Fe depletion
Angular momentum too large
Current model
Giant impact model
Object the size of Mars hit Earth
Part of Earth broke off = Moon
Came after Apollo program ~1974
Iron remains in Earth’s core
Refractory element enrichment, volatile element depletion, magma ocean
Isotopic composition
C0mes from Earth’s mantle
Angular momentum—off center impact
Moon either near equator.
(volatiles on Moon haven’t been boiled away so MOT ! 100% explanation.
Magma ocean
Outer crust 200 km thick and Molten
Solified, Moon shrunk
Wrinkle ridges from LRO camera
Contraction still happening as the Moon cools off. Too small to measure but
still happening at rate of finger nail growing—thrust faults where
one part overlapping another
Pic -light coming from SW and wrinkle moving left over right
Can age rocks and the craters
(1 billion - 1.8 billion years)
Still learning more
Magma ocean rock image
Anorthosite 4.44-4.51 Ga (giga-annum, giga-Earth years)
Moon formed about same time as Earth . . .
Trocolite
4.2-4.3 Ga
Impact basin from GIANT impact
Blow out a big hole, gets hot enough to melt material and impactor—for
secondary craters
Deeper down material heats up and can escape and fill crater afterwards
Lunar IMPACT BASINS: IMBRIUM RING
ORIENTALE BASIN
Mountains of the Moon formed from IMPACTS
(Earth has plate tectonics, weather etc.)
Impacts form hydrogen
Siberia-enormous asteroid or comet 1908
Air burst
Not found Fe/Ni fragments
Dinosaur meteor 10 km (6 mi) across
(Recent meteor near Earth was the size of a bus)
Moon mountains formed by impacts and ejecta
Some more than one ring—terraced cratering
Ejecta-everything thrown out of the impact during crater formation
Regolith-“soil” of the moon
Formed by the impact—pulverized, broken rock.
Breccias and Impact melts
Breccia made of pre-existing rocks mixed-like concrete
Polymict breccia pic #67016
Ejecta heated/melted and solidifies
Polymict breccias are breccias made of breccias—secondary impacts
Impact melts and clasts pic # 15445
E1 gives directio of the rock when it was picked up
Mare volcanism
Mare imbrium
Molten material, basalts
#15555 3.3Ga old (N1 orientation) pits in rocks from micrometeorits-no
atmosphere
Laser ranging reflector-left on Moon
Japanese mission Kaguya
Marius hills (bumps) all volcanoes)
No gigantic volcanoes on the Moon
Far side—Thorium anomaly—high % thorium
See dome and crater—dome is thorium anomaly
Rocks, boulders around it.
Unusual to see volcanic domes in highlands—this is silicic volcanism—less
iron and Mg-Moon not all basaltic volcanism
Viscous on Moon,
First out basalt but some more viscous and cooking/evolving longer making
different magma
800 million-1 billion years old
The bigger the more complex craters
Slmall = bowl (like Meteor crater)
Then get terraced=Copernicus with peak in center (93 km diam)
Other peaks from rebounds
Tycho—LRO camera
Central peak NEW pic from June 2011 2 miles high
Lighter colored rock?
SEE Kuyuga mission fly-around
3.8 billion
overall crater
3.0 maria
not too different from today
40 years ago
Hadley Rille
Took a rover
To investigate what caused the rille, the Mare and the Highlands were
close—looked like a lava tube that collapsed
Previously thought carved out by water—No!! Nobel prize winner Uri
The Genesis rock
Wanted the early crust of the Moon
Anorthosite—4.1 billion years old some of the oldest crust of the Moon
30 km in 7 daysApollo 17
Mars rovers did 30km in 7 years
Rick Varner
Goddard
Borrowing Lunar samples
Public affairs office or being studied
Origin of moon and solar system
NASA analysis
Lunar sample compendium
http//:curator.jsc.nasa.gov/lunar/compendium.cfm
or Google lunar compendium
ACTIVITY: Modeling planetary interiors
dimensions of Earth’s inner core, outer core, mantle and crust
Measure on bottle how deep each layer will be
How to choose your layers—density wise.
Make a bottle of the Moon—you get to decide which materials will
differentiate for the crust to float and the core to sink
What are the current measurements?
Oil, water, syrup, gravel, wooden beads, plastic beads
You can use any other readily available materials
Geologic Mapping of the Moon
Density part of planetary formation
(could freeze water to get all solid)
Gr 8-HS
Activity focusing on Apollo 15 landing site
Determine the relative ages of various features on the Moon
Superposition of units—younger units on the top
Craters in middle of mare
Craters are YOUNGER
In Earth geology go into field and know younger layers on top and correlate
layers with fossils, etc.
On the Moon use photographs
Some unit ages obvious
Cross cutting, etc.
Highlands older and mare came in later filling cracks, etc.
Embayment
Hadley’s rille younger than the mare
Hadley’s rille is crosscutting the mare
(We’ve been told that the rille is a lava tube that had collapsed. (The top of
the lava cools first and solidifies.)
(On Earth could always tell if a fault was younger than the surrounding
material—if fault buried, it’s older, if fault exposed (on top) the fault is younger
Just relative dating—it does not date the features exactly
Lunar feature analog
Central crater uplift: Tycho : Mistastin Crater Canada
Crater ejecta Copernicus: Meteor crater
Dome Gruithusen Hills : Mt St Helens Washington
Lunar mare (basalt) Sinus indium: snake river plain ID
Rille: Hadley’s rille:
Kileau volcano Hawaii
Terraced crater
Earth and Moon STATISTICS
What do people see when they look at the Moon
Mars Odyssey pic of Earth and Moon in the same pic
Moon rotates every 27.3 days
Tilted 7 deg to the ecliptic
(Earth is 23.5)
Elliptical orbit
360000 km (224000 mi)
406000 km (252000 mi)
revolution of Moon is 27.3 days AS WELL. The Moon is tidally locked with
the Earth. New moon to new moon is two days later
2 types of month
synodic—with reference to Sun
sidereal—27.3 days 360o rotation ref to stars (its OWN rotation
Takes 27.3 days to revolve around Earth BUT the Earth has moved a bit so
takes 29.5 days to getback to the new Moon.
Tides decreasing and distance from earth increasing by ~2 cm /year
Earth’s rotation slower—21 hours in time of the dinosaurs—end of
cretaceous
Moon rotates and revolves at the same rate so only on side is presented to
the Earth.
South Pole Aikin Basin—on the FAR SIDE of the Moon
Eclipses:
Moon at 5o to the Earth’s plane
Moon revolves counterclockwise, and Earth rotates counterclockwise
Activity person as Moon moving around another person as the Earth
Another activity for 25% of class that doesn’t help the understanding
Penny Moon Quarter Earth
Abe Lincoln up with nose facing Earth/quarter
As you move the penny counterclockwise around the Earth (quarter), keep
the nose pointing towards the Earth (so Moon is rotating as the Moon revolves
around the Earth.)
Field Trip
Clean-room APL
Goddard Geophysical and Astronomical Observatory
http://cddis.nasa.gov/ggao/
laser ranging facility
VBLI
12 m satellite dish
2-12 GHz
LROLR.gsfc.nasa.gov
Beryllium casing of the receiver unit—Be used because its thermal expansion
approx. = to that of the crystal, etc.
80 x 106 km  Mars record for one way
24 x 106 km record for 2-way laser to MESSENGER probe
MOBLAS 7 “mobile laser” been there since ‘86
Can see the laser pulsing
SLR satellite laser ranging
ILRS
Google International Laser Ranging Service
(1 arc sec = 1/3600 deg)
NGSLR
Next Generation satellite laser ranging—less energy—greater frequency—
can’t see it pulsing
MOBLAS 7 and NGSLR lasers turned on and both focused on the same
satellite
Saw the intersection track across the sky as it tracked the satellite
(Doesn’t interfere with aircraft because a 3o radar beam (much wider than
the 1 arc sec laser) covers the laser beam and will cut off the laser if an aircraft
enters the radar beam)