Asteroids and Comets Don T Have Large Amounts of Anorthosite

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

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

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)