Page 92 - Apollo Moonships

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GLOSSARY
ABLATION
Dispersing of excessive heat from a surface by vaporization, chipping, melting, charring or other process of specially designed coating material (ablative material).
ACCELERATION
Rate at which the velocity of an object changes over time. An object’s acceleration is the net result of any and all forces acting on the object.
ACTUATOR
Motor responsible for transforming electrical signals into mechanical motion.
AEROZINE 50
Liquid fuel that consisted of a 50/50 mix
by weight of hydrazine and unsymmetrical dimethylhydrazine (UDMH). This type of fuel is mainly used for interplanetary probes and spacecraft propulsion because unlike other more common propellants like liquid oxygen or liquid hydrogen Aerozine 50 is liquid at room temperature and can be stored in liquid state without significant boil off, thus making it a storable propellant better suited for long term interplanetary missions.
ASCENT ENGINE
The 3 500 pounds–force Jet engine rocket that propelled the Lunar Excursion Module during the lunar landing phase.
ASCENT STAGE
Upper section of the Lunar Excursion Module that housed the crew cabin, the control panels and the ascent engine.
ATMOSPHERE
Layer of gases surrounding a planet or other material body of sufficient mass that is held in place by the gravity of the body. An atmosphere is more likely to be retained if the gravity is high and the atmosphere’s temperature is low.
ATMOSPHERIC REENTRY
Return from outer space into the Earth’s atmosphere of a spaceship or a celestial body.
ATTITUDE
Position or orientation of an spacecraft with respect to an inertial frame of reference or another entity as the fixed stars.
ATTITUDE CONTROL
Exercise of control over the orientation of the spacecraft rotational axis (X, Y and Z)
AXIS
Any of the tree straight lines about which an aircraft or spaceship rotate. This axis are known as X (Yaw), Y (Pitch) and Z (Roll).
BURN
Ignition of a jet engine. Burn time is the duration of a jet engine thrusting period.
BURNOUT
The point when the combustion ceases in a rocket engine.
COMBUSTION CHAMBER
Part of an engine in which fuel is burned.
COMMAND AND SERVICE MODULE
One of two spacecraft, along with the Lunar Module, used for the Apollo Program which
landed astronauts on the Moon. It consisted of two segments: the Command Module, a cabin that housed a crew of three astronauts and equipment needed for reentry into the Earth’s atmosphere and splashdown; and a Service Module that provided propulsion, electrical power and storage for various consumables required during a mission. The Service Module was cast off and allowed to burn up in the atmosphere before the Command Module re- entered and brought the crew home.
COMMAND MODULE
Spaceship with a truncated cone measuring
10 feet 7 inches (3.2 m) tall and having a diameter of 12 feet 10 inches (3.9 m) across the base. The forward compartment contained two reaction control engines, the docking tunnel, and the components of the Earth Landing System. The inner pressure vessel housed the crew accommodations, equipment bays, controls and displays, and many spacecraft systems. The last section, the aft compartment, contained 10 reaction control engines and their propellant tanks, fresh water tanks, and umbilical cables.
CRYOGENIC
Relating to extremely low temperatures (–319°F or less). Cryogenic propellants remains liquid only in supercold conditions.
DESCENT ENGINE
Variable throttle rocket engine used in the Apollo Lunar Module Descent Stage. It used Aerozine 50 fuel and N2O4 oxidizer.
DESCENT STAGE
Lower section of the Lunar Excursion Module designed to support a powered landing and surface extravehicular activity on the moon. When the excursion was over, it served as launch pad for the ascent stage.
DIPLEXER
Device that permits an antenna to be used by two transmitter at the same time.
DISPLAY
Output device for presentation of data.
DOCKING
Mating between two spacecrafts.
DROGUE SYSTEM
Latching mechanism used in the Lunar Excursion Module into which the Command Module probe was pushed during docking. The drogue was removed by the Apollo astronauts to have access to the lunar lander interior.
EXTRAVEHICULAR ACTIVITY
Any activity done by an astronaut outside a spacecraft beyond the Earth’s appreciable atmosphere. The term most commonly applies to a spacewalk made outside a craft orbiting Earth, but also has applied to the lunar surface exploration (known as moonwalks) performed by the Apollo Program from 1969 to 1972.
FAR SIDE OF THE MOON
Hemisphere of the Moon that always faces away from Earth. Only one side of the Moon is visible from Earth because the Moon rotates about its spin axis at the same rate that the Moon orbits the Earth, a situation known as synchronous rotation or tidal locking.
FUEL
Any material that store potential energy in forms that can be practicably released and used for work or as heat energy. The concept originally was applied solely to those materials storing energy in the form of chemical energy that could be released through combustion, but the concept has since been also applied to other sources of heat such as nuclear energy.
GIMBAL
Pivoted support that allows the rotation of an object about a single axis.
GNOMON
Part of a sundial that casts the shadow.
GUIDANCE COMPUTER
Digital computer with erasable and fixed memory used to calculate the attitude and thrust commands to maintain a course or correct a deviated a flight path.
HEAT SHIELD
Coating substance designed to reject the excessive heat from an outside source by either dissipating, reflecting or simply absorbing the heat. An ablative heat shield consists of a layer of plastic resin; the outer surface of which is heated to a gas which carries the heat away.
HONEYCOMB SANDWICH
A type of construction in which the space between the upper and lower surfaces is occupied a strengthening material of a structure resembling a honeycomb mesh.
INERTIA
Resistance of any physical object to any change in its state of motion, including changes to its speed and direction.
INERTIAL MEASUREMENT UNIT
Main unit of the Apollo inertial guidance system, that consisted in a stable platform equipped with three gyroscopes, three integrating accelerometers and three angular differentiating accelerometers used to sensed the attitude changes or accelerations of the spaceships.
INTERFACE
Place when to parts of a single system meet and communicate whit each other.
INTERSTAGE SKIRT
Flange of a rocket section that provide a ready means of fitting another stage or section to it.
JETTISON
To throw or eject from a ship, aircraft or vessel a cargo to lighten the vehicle. Discard in space a spacecraft or part of it.
LUNAR ROVING VEHICLE
Battery-powered four-wheeled rover used on the Moon in the last three missions of the Apollo Program during 1971 and 1972.
MANNED SPACE FLIGHT NETWORK
Set of tracking stations built to support the Mercury, Gemini, Apollo, and Skylab programs.
MICROMETEOROID
Tiny meteoroid. A small particle of rock in space, usually weighing less than a gram. Particle, often remnants of comets, that travels through space.