8: The Moon

Apollo 11

1969 H-class mission

• neil armstrong, buzz aldrin and mike collins

• sea of tranquility

• 21.6kg rocks and soils

• FIRST LUNAR SAMPLES

• basalts, pyroxenes and plagioclase

  

Apollo 12

1969

• Pete Conrad, alan bean, richard gordon

• ocean of storms

• 34.3kg rock

• mostly basalt

• KREEP rich in K, REE and Phosphorus

• COPERNICUS IMPACT 800Mya

  

Apollo 14

1971 H-class mission

• alan sheppard, edgar mitchell and stuart roosa

• Fra Mauro

• 42.3kg rocks

• date imbrium basin

• impact ~3.85Ga

Apollo 15

1971 J-class mission

• david scott, jim irwin, al wordon

• Hadley Rille

• 77.3kg rocks

• Edge of Mare Imbrium

• lava channel

• vesicles - gas rich, explosive volcanism, anorthosite

  

apollo 16

1972 J-class mission

• John young, charlie duke, ken mattingly

• Descartes Highlands

• impact melt 3.92ga

• anorthosites 4.5ga

  

apollo 17

1972 j-class mission

• gene cernan, harrison schmidt, ron evans

• 110.5kg rocks

• ORANGE SOIL - melt glass

• NORITES and TROCTOLITES

what are norites

plagioclase and pyroxene

what are troctolites

plagioclase and olivine

Who was the only geologists to walk on the Moon?

Jack Schmidtt: others were given a crash course in geology

Lunar rover capabilities

• some issues: dust covers equiptment

• up to 30km covered each mission

Summarise the apollo missions

What si the farside vs darkside of the moon

Farside: faces away from us - less is known

Darkside: faces us, more mare (darker)

how did moon exploration begin?

• soviet us spacerace - politically motivated

• 90s it picked up in momentum

• NASA Artemis would like to return people to the moon

• Change 5 & 6 both important

  

USSR and moon missions

• first soviet mission 1959 - flyby - first pictures of darkside (17)

• Lunokhod Rovers

• first robotic sampling of planetary surface

• funny shapes

what are Lunokhod Rovers

• ussr spacecrafts on moon

• sited surveys for possible crewed landings

• onboard experiments: cameras, soil, x-ray

• Luna 17: Mare Imbrium 1970, 10.5km

• Luna 21: Mare Serenitatis 1973, 37-42km

America and moon missions

• ranger programmes 1961-1965: hard landers (1-6 failed, 7-9 gave images till impact)

• Apollo: 2.4-3.5bil per launch, 6 successful landings 1969-1973 - 382kg rocks

  

Where did the apollo missions land?

All equitorial

o   Apollo 11 – Mare Tranquility mare basalt

o   Apollo 12 – Oceanus Procellarum mare basalt

o   Apollo 13 – did not land

o   Apollo 14 – Fra Mauro highlands (Imbrium ejecta)

o   Apollo 15 – Hadley Rille and Imbrium mare basalt

o   Apollo 16 – Cayley Plains and Descartes Highland

o   Apollo 17 – Taurus Littrow valley mare basalt and highlands

Lunar rocks

All shapes and sizes

• middle shows cesicular basalt

• bottom left shows apollo 15 white highland genesis rock

• top right shows orange glass beads (volcanic, fire fountain events)

Lunar minerals

• Silicates: plag, pyroxene, olivine, quartz

• oxides: ilmenite, spinel

• FeNi metal

• troilites (iron sulphide)

• glass

• ferroan anorthosites

• magnesian suite

• high alkali suite

  

observations and missions to see the moon from orbit

• earth based observations

• moon satellites

• 1950s-1960s: Luna, lunar orbiter, ranger, surveyor, apollo

• 1990s-now: galileo, clementine, lunar prospector, SMART1, kaguya, change 1&2, LRO, LCROSS, LADEE

• photography: illumination angle, oblique vs perppendicular sun

  

Clementine mission

• CCD camera mapping of lunar surface in 5 UV/VIS wavelength

• created topographic map

• apparent nearside/farside crustal asymmetry

• farside/nearside crustal asymmetry

• big basin southpole - aitken

  

chemical diversity

• farside highlands - Al2o3, CaO rich, FeO poor (anorthosites)

• nearside mare regions - FeO, TiO2-rich (basalts-lavas)

  

Makeup of the lunar crust

1. Primary: anorthosites (highlands)

2. secondary crust: volcanic/magmatic - intrusive volcanic processes or extrusive (mare)

3. tertiary crust: impact soil, sediments

Lunar geological ages

1. Pre-Nectarian

2. Imbrian

3. Eratosthenian

4. Copernican

   

Timing of Lunar origin

~4.5Ga

What is the Giant Impact theory?

• moon likely formed in giant impact event 4.456ga

• ~62Mya after formation of Solar System

• significantly later than formation of asteroids and Mars

• Theia (potential impactor, mars-sized)

  

Lunar differentiation

• small core, mantle and crust

• core ~330km (1-3% total moon mass)

• core formation event dated using lunar rocks by Hf-W system

• material remaining after core formation likely forms overlying magma ocean

  

lunar ingterior differentiation and crust formation

• magma ocean cooled

• minerals crystallised

• time of crystallisation unknown

  

how does lunar ocean crystallisation occur?

• dense minerals rich in Mg sink to form lunar mantle

• after ~80% magma ocean crystallisation plag formed as it is less dense and floats

• late stage KREEP plase and Fe-rich minerals (ilmenite) form and trapped between mantle and crust

What is Ferroan Anorthosite

• pre-nectarian >3.92ga

• primary crust

• white rock

• rich in Al, Ca and Si (plag)

• farside dominated by FAN rocks

  

When was the formation of lunar crust?

4.5-4.3Ga

When did early lunar magmatism occur?

• 4.5-4.0Ga

• secondary crust

• generated suites of intrusive events and erupted lavas

• High Mg, Alkali, Al and KREEP basalts

when did impact bombardment occur

• 4.5-3.8Ga to present

• asteroids, comets and dust impacts

• large impact craters and basins form on moon

Impact craters

What is the Aitken Basin?

• Largest basin in SS

• 2500km diameter, ~13km deep

• excavated through crust into underlying mantle

• formed ~4.33Ga

What is Lunar Cataclysm?

• Late Heavy Bombardment

• Violent Early Solar System

• cluster of ages, 3.85Ga

• all basins formed in 20Ma or 200Ma

what is the Nice Model?

• scattering of small objects in SS due to migration of giant planets (3.9Ga) - more impactors in inner solar system

What are the Lunar Maria?

• topographic lows, fe rich, low albedo

• impact basins with dark basaltic flows

• 3.8-3Ga

• effect of lunar volcanism

• basalt eruption and emplacement

• pyroclastic glass

What is the Hadley Rille?

• Apollo 15

• sinuous lava channel that ranges in depth (180-270m)

• 370m deep at apollo landing site