Lunar Earths Moon

Question 1

What type of satellites have been to the moon?

Answer 1

Lunar orbit - mapping satellite
Surveyor lander - in situ analysis
Rammer mission - took close up pictures

Question 2

What are the FAN deposits?

Answer 2

Lunar highlands (crustal) - mare basalts

Question 3

Volcanic features on the moon?

Answer 3

Rilles - resemble the shape of river valleys on earth. Small pitted structures formed by the collapse of lava tubes AND/OR the thermal erosion between weak points
Pressure (wrinkle ridges)
Impact basin flooding

Question 4

Summary of the main lunar rock types

Answer 4

FAN - plagioclase rich crustal rocks 
Mg-suite - gabbros
High-alkali suites - granites 
KREEP - basalts
Mare basalts - mantle melt
Impact melt breccias 
Mixing of them = Regolith (lunar soil)

Question 5

Is there a magnetic field around the moon now and reasons for or against and the same with the past?

Answer 5

A magnetic field implies presence of a mobile electrically conducting core. The moon ford no have a dipolar magnetic as this would be generated by a geodynamo.
However, early history geodynamo as basalts revealed substantial remanent magnetism thus at time of crystallisation a strong magnetic field. Also, sensitive free orbiting magnetometers detect localised external magnetic fields associated with large craters

Question 6

Remote sensing on the moon?

Answer 6

X-ray fluorescence - maps relative abundance of elements e.g. Mg. this provides information about spatial distribution and lithology cal composition - investigating crustal heterogeneity, lava flow mapping etc.
Light reflectance (Multi-mapper)
Gamma ray spectroscopy (natural radioactivity) 
Neutron spectrometer (h - water)
Alpha particle emoter (Radom gas)

Question 7

What did the satellite clementine achieve when launched in 1994?

Answer 7

First satellite to map geochemically 
Mapped the moon in different wavelength 
CCD camera mapping In wavelengths - ratios of different bands where used to map abundance of elements. This created distribution of mare basalts and basaltic composition diversity e.g. KREEP 
Farside - anorthositic (FAN)
Nearside - Mare basalts

Question 8

What are the theories behind the moons formation?

Answer 8

Rotational fission - Darwin (1880) believed that the moon was spun off by the rotating earth - this would have needed 4x the angular momentum of the earth
Binary accretion - created from a disk of material similar to other planets in the solar system - this would give identical geochemical properties to the earth
Gravitational capture - capture from elsewhere In the solar system - insufiecent KE as would either pass or collide with earth as well as geochemical similarity
Giant impact - Hartman and Davis (1880) the earth was struck. H a mars sized satellite early in history. Moon formed in earth orbit by debris from the collision. Accounts for chemical evidence

Question 9

What happened to the moon post collision?

Answer 9

The moon become a large ball of super heated magma. From this heavier elements (Fe-rich) sunk to form an unstable core where elements left over formed the magma ocean

Question 10

What is the magma ocean model?

Answer 10

The magma ocean model hypothesis that plagioclase rose to the surface forming a crust (FAN) where as mafic minerals sunk. During this meteorites continued to hit the moon causing localised regimes of reheating and melting. These rocks are referred to as lunar plutonic suite (HMS) and compositional different from the FAN crust

Question 11

How do KREEP and mare basalts form?

Answer 11

Under neither the plagioclase lies a dense fe-rich mafic phase. From this forms both KREEP and mare basalts
KREEP - trapped late stage residual melt is enriched with incompatible elements
Mare basalts - mafic accumulates subsequently partially melt to derive the younger mare basalts

Stricter of the moon from seismic
Crust thickness 50km
Moonquakes go down to 100km

Question 12

Stratigraphy of the moon?

Answer 12

Layered anorthositic sequence (FAN)
Intruded HMS
Intruded secondary mare basalts
Subsequent alteration by continental impact

Question 13

Missions to the moon and samples returned with there key discoveries?

Answer 13

Apollo and lunar returned samples from equatorial latitude on the near side showing an Al rich suite of crustal rocks
Ferroam anorthosites (>90% plagioclase)
Mg suite - gabbro
High alkali suite - granites
Mare basalts - partial mantle melting (no hydrous mineral present) ancient and modern
KREEP (potassium REE and phosphorous) - mare basalts (mantle)
Age - 4.5-4.2Ga