A Brief Geologic History of The Moon Walter

A Brief Geologic History of The Moon Walter S. Kiefer Lunar and Planetary Institute

Apollo Program Accomplishments • 6 human landings • 14 EVAs, total 80. 1 hours • Longest traverse 18 km • 382 kg samples

Apollo Landing Sites Apollo 11 Apollo 17 Apollo 15

Sample Collection

Sample Curation

Telling Time: Radioactive Decay

The Lunar Near Side 15 12 14 17 11 16 Visual Image Topography

The Lunar Farside Visual Image Topography

Lunar Mare and Highlands Mare Serenitatis

Lunar Interior Structure

Lunar Formation Models Capture Binary Accretion Major Problems Fission • Capture: Hard to dissipate orbital energy • Fission: Lack of angular momentum • Binary accretion: Chemical differences (iron, volatiles)

The Giant Impact Model

The Magma Ocean

Magma Ocean Rocks 76535 Troctolite 4. 2 -4. 3 Ga 60025 Anorthosite 4. 44 -4. 51 Ga

Impact Basin Formation

Lunar Impact Basins Imbrium Rim Orientale Basin

Breccias and Impact Melts 15445 Impact melt + clasts 67016 Polymict Breccia

Mare Volcanism Mare Imbrium SW Mare Imbrium

Hadley Rille 0. 5 -2 km wide 200 meters deep

Marius Hills Volcanic Domes

Lunar Basalts 15016 15555 3. 3 Ga

Ryder Crater 17 km diameter

Impact Crater Structure

Tycho Crater 85 km diameter 4. 7 km deep

Tycho Central Peak Central peak 2 km high, 12 km across

Time Evolution of Moon 3. 8 billion years 3. 0 billion years Today