Late Heavy Bombardment (LHB) hypothesisthe theory that meteorite bombardment of the inner solar system declined after accretion of the planets and then peaked again at 3.9 Ga. This event is proposed to have limited the emergence of life on Earth

LCROSSthe Lunar Crater Observation and Sensing Satellite, a secondary payload to be launched with the Lunar Reconnaissance Orbiter

LEAGthe NASA Lunar Exploration Analysis Group (LEAG) is responsible for analyzing scientific, technical, commercial, and operational issues associated with lunar exploration

LPRPthe Lunar Precursor and Robotic Program of the Exploration Systems Mission Directorate

LRONASA’s Lunar Reconnaissance Orbiter

LSAMNASA’s Lunar Surface Access Module

Lunar Aa Japanese Aerospace Exploration Agency lunar mission

lunar dynamofor the ancient Moon, the possibility that a lunar magnetic field might have been generated by the internal motion of an iron-rich molten core

Lunar Magma Ocean hypothesisthe hypothesis that when the Moon formed, it was molten to a depth of hundreds of kilometers; its crystallization produced the primary crust and mantle

mafic materialsa dark-colored, igneous rocks rich in ferromagnesian minerals

magmamolten rock from the interior of a planetary body

mantlethe geologic zone above the core and below the crust

MERNASA’s Mars Exploration Rover

obliquitythe angle between the orbital plane of an object and the plane of its rotational equator

olivinea magnesium iron silicate mineral (FeMg)2SiO4

parautochthonousa rock type intermediate in tectonic character between those found at the site of their formation and those that come from another site

Permian/Triassic boundaryon Earth, the layer of rocks between the Permian and Triassic periods, about 251 million years ago, the time of a major extinction event

petrologya branch of geology dealing with the composition, mineralogy, origin, occurrence, history, and structure of rocks

plagioclasea type of feldspar and one of the most common rock-forming minerals, (CaNa)(AlSi)4O8

plutona large body of igneous rock created by the subsurface intrusion of magma

pre-Nectarian periodthe lunar geologic period from the formation of the Moon to about 3.9 Ga ago

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