chondritea type of stony meteorite containing chondrules, roughly spherical bodies containing pyroxene or olivine embedded in the matrix

chronostratigraphythe branch of stratigraphy that studies the absolute age of rocks

cool early Earthhypothesis that the surface of Earth cooled relatively quickly after the formation of the core and the Moon, such that oceans and conditions hospitable for life could exist by 4.3 Ga

Copernicanthe lunar geologic period from about 1.1 Ga ago to the present

Cretaceous/Tertiary boundaryon Earth, the boundary between rocks of the Cretaceous and Tertiary periods, about 65.5 million years ago, around the time of a major extinction event

cumulatesigneous rocks formed by the accumulation of crystals from a magma

detrital zirconszircon crystals found in erosional deposits. Some grains are as old as 4.4 Ga and are the oldest known samples of Earth

differentiated planetary bodya planetary body whose interior is formed of separate internal geologic units with distinct mineralogical characteristics, e.g., core, mantle, crust

Erastosthenianthe lunar geologic period from 1.1 Ga to 3.2 Ga ago

ESMDNASA’s Exploration Systems Mission Directorate

EVAextravehicular activity

Exospherethe highest layer of an atmosphere

feldspathicpertaining to rocks rich in feldspar minerals

Gaone billion years

geochronologydetermination of the time at which a rock crystallized, usually by radioactive decay of parent-daughter isotope pairs: U-Pb, Sm-Nd, K-Ar, or Rb-Sr

hyperthermophilemicroorganisms that live in hot environments, above 60°C

igneous rocksrocks crystallized from a magma

ISRUin situ resource utilization

Isua greenstone rocksa geological formation in southwestern Greenland (Isua) composed of ancient surface rocks

KREEPlunar basalts and breccias that are rich in potassium (K), rare-earth elements (REE), and phosphorus (P)

Kuiper Belta region of the solar system distributed in a roughly circular disk extending from 40 to 100 astronomical units from the Sun



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