Glossary of Space Exploration Terminology

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C
C-band
A range of microwave radio frequencies in the neighborhood of 4 to 8 GHz, used for spacecraft communications on Mercury and Gemini flights (~5 Ghz).
C-stoff
A rocket fuel used by Germany in World War II: 30% hydrazine hydrate, 57% methanol, 13% water with traces of potassium cuprocyanate. Used in conjunction with T-stoff oxidizer: 80% hydrogen peroxide with 1 to 2% oxiquinoline as a stabilizer.
Calibration
Setting an measuring instrument before measuring for accurate results.
Carrier
The main frequency of a radio signal generated by a transmitter prior to application of modulation.
CAS
Chinese Academy of Sciences.
CAST
Chinese Academy of Space Technology.
CAT
Capsule Ariane Technologique.
Catalytic decomposition engine
A mono-propellant engine in which a liquid fuel decomposes into hot gas in the presence of a catalyst. The fuel is most commonly hydrazine.
CCD
Charged Coupled Device.
CDS
Command & Data Subsystem.
Celestial sphere
The apparent sphere of sky that surrounds the Earth; used as a convention for specifying the location of a celestial object.
Centripetal force
A force which is directed towards the center of rotation.
CEO
Close Earth Orbit.
CETI
Communication with Extra-Terrestrial Intelligence.
Chaff
Metallic foil ejected by a reentry module to enhance its radar image.
Charged coupled device
An imaging device consisting of a large-scale integrated circuit which has a two-dimensional array of hundreds of thousands of charge-isolated wells, each representing a pixel.
Cholorella
A genus of unicellular green algae, proposed for converting carbon dioxide into oxygen for use in spacecraft.
Chromosphere
A reddish layer in the Sun's atmosphere, the transition between the photosphere and the corona.
Cislunar
Relating to the space between the Earth and the orbit of the Moon.
CM
Command Module.
CNES
Centre National d'Etudes Spatiales (France).
CO
Circular Orbit.
Coherence
The property of being coherent, e.g. waves having similar direction, amplitude and phase that are capable of exhibiting interference.
Coma
The cloud of diffuse material surrounding the nucleus of a comet.
Combustion
A chemical reaction between two or more substances that releases heat, light, and gases.
Combustion chamber
The chamber in a rocket where the fuel and oxidizer are ignited and burned. By common usage the expansion nozzle is included as part of the combustion chamber, particularly for liquid-propelled rocket engines.
Comet
A body of small mass but large volume, compared to a planet, often developing a long luminous and partly transparent tail when close to the Sun.
Command & data subsystem
The onboard computer responsible for overall management of a spacecraft's activity.
Command module
The compartment of a spacecraft which contains the crew and main controls, and is used as the reentry vehicle.
Composites
Structural materials of metal alloys or plastics with built-in strengthening agents, e.g. carbon fibers.
Constellation
A group of stars that make a shape, often named after mythological characters, people, animals, and things.
Control rocket
A vernier or other rocket used to control the attitude of, or slightly change the speed of, a spacecraft.
Coolant
A medium, usually a fluid, which transfers heat from a object.
Core
The innermost layer of a planet or star.
Coreolis effect
Dizziness or nausea experienced when an astronaut in a spinning spacecraft moves his head in the opposite direction.
Corona
The Sun's outer layer. The corona's changing appearance reflects changing solar activity.
Coronal mass ejection
A huge cloud of hot plasma, expelled sometimes from the Sun. It may accelerate ions and electrons, and may travel through interplanetary space as far as the Earth's orbit and beyond it, often preceded by a shock front. When the shock reaches Earth, a magnetic storm may result.
Cosmic ray
An extremely energetic (relativistic) charged particle.
Cosmic year
The time it takes the Sun to revolve around the center of the galaxy, approximately 225 million years.
Cosmonaut
The Russian term for an astronaut. A space traveler.
COSPAR
The Committee on Space Research (established October 1958).
Countdown
A count in inverse numerical order, in hours, minutes and finally seconds, of time remaining before the launch of a rocket.
Crater
A round impression left in a planet or satellite from a meteoroid.
Crust
The outer layer of Earth and other terrestrial planets.
Cryogenic
A rocket fuel or oxidizer which is liquid only at very low temperatures, e.g. liquid hydrogen which has a boiling point of -217.2oC (-423oF).
CSA
1. Canadian Space Agency, 2. Chinese Society of Astronautics.
CSAA
Chinese Society of Aeronautics and Astronautics.
CSM
Command/Service Module.
Current
The amount of electric charge flowing past a specified circuit point per unit time.
Cut-off
The action of stopping a process abruptly, such as shutting off the flow of propellant to a rocket engine.

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Rocketry & Space Technology

Glossary courtesy of Robert Braeunig's
Rocketry & Space Technology website.