bulk composition: The makeup of a celestial body as a whole.

CAPTEM: Curation and Analysis Planning Team for Extraterrestrial Materials.

carbide: A compound of carbon with a more electropositive element or group.

CAREER award: National Science Foundation Faculty Early Career Development Program.

CATE: Cost and technical evaluation; specifically, a particular methodology for assessing the cost, schedule, and technical risk associated with a spacecraft mission.

CCSR: Cryogenic Comet Sample Return.

CH4: Methane.

chirality: The right- or left-handedness of an asymmetric molecule.

CHNOPS: Carbon, hydrogen, nitrogen, oxygen, phosphorus, sulfur—the six elements essential to life as we know it.

chondrite: A stony meteorite, unaltered from its parent body.

chondrule: Round grains that make up a fraction of chondrites, formed from molten or partially molten droplets of minerals.

CIDA: Cometary and Interstellar Dust Analyzer (on NASA’s Stardust spacecraft).

circumstellar disk: A broad ring of material orbiting around a star.

clathrate: A chemical substance consisting of a lattice of one type of molecule (e.g., water) trapping and containing a second type of molecule (e.g., methane).

clathration: The chemical process leading to the formation of a clathrate.

CNES: Centre National d’Etudes Spatiales (the French space agency).

CNSR: Comet Nucleus Sample Return.

CoBRA: Complexity Based Risk Assessment.

comparative planetology: Use of the knowledge gained from the study of one planetary body to understand processes and phenomena of another.

COMPLEX: Committee on Planetary and Lunar Exploration (National Research Council).

corotating: To rotate jointly, as with another object.

covalent bond: A chemical bond formed when atoms share electrons.

cryogenics: The branch of physics dealing with the behavior of matter at very low temperatures.

cryosphere: Portions of a planetary body where water is in solid form.

cryovolcanism: The eruption of water and other volatile materials onto the surface of a planet or moon due to internal heating.

CSSR: Comet Surface Sample Return.

D/H ratio: Deuterium-to-hydrogen ratio.

DARPA: Defense Advanced Research Projects Agency.

diagenesis: The sum of the physical, chemical, and biological changes that take place in sediments as they become consolidated into rocks, including compaction and cementation, but excluding weathering and metamorphic changes.

differentiation: The process by which the interior of a planetary body separates into layers of different compositions.

DOE: Department of Energy.

dropsonde: A meteorological instrument package designed to be dropped from altitude in a planetary atmosphere and to make measurements as it falls to the planet’s surface.

DSN: Deep Space Network (NASA).

dynamo: An electromagnetic process in which the movement of conductive material gives rise to a magnetic field.

eccentricity: A measurement of the degree to which an elliptical orbit deviates from a circular orbit. An ellipse of zero eccentricity is a circle.

ecliptic: The plane of Earth’s orbit around the Sun.

EDL: Entry, descent, and landing.

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