abort: to cancel; to stop something that is already in progress

aeronautic: the theory of navigation through air or space

aft: near or at the rear of an aircraft or other vessel

AOA: abort once around; a launch-abort procedure in which the shuttle lands after nearly one trip around Earth

APU: auxiliary power unit; each of three units that provide power to the shuttle's hydraulic system; the hydraulic system controls the orbiter's rudder, landing gear, flaps, and other steering and flying structures

ascent: journey upward

atmosphere: the mixture of gases that surround the planet

ATO: abort to orbit; a launch-abort procedure that takes the orbiter into a lower-than-planned Earth orbit; used if a main engine shuts down too soon

avionics: the electronic systems used to fly a vehicle

bacteria: microscopic living things; certain bacteria can cause disease

CAPCOM: Capsule Communicator; person who handles all communications between Mission Control and the Orbiter

cardiovascular system: the system that moves blood and oxygen throughout your body; includes the heart, veins, and arteries

coolant: something that is used to cool another thing, e.g. a liquid that flows through a hot engine to draw off heat and keep the engine cool

CRT: cathode ray tube; commonly known as computer screens; the Orbiter's CRTs display information to the crew

cryogenic: extremely low temperature

dehydration: removal of moisture from foods such as meats and vegetables; this process preserves the food and reduces its weight for space travel

depressurize: to decrease the air pressure within a closed area 

diameter: the width or thickness of a circular or cylindrical object; a straight line passing through the centre of a circular or cylindrical object 

DAP: digital autopilot; an automated system used to maintain a specific course or altitude in orbit

drogue: cone-shaped

entry: entry back into the EarthÕs atmosphere from space

ET: the External Tank of the Space Shuttle; this tank carries liquid oxygen and liquid hydrogen; the Shuttle burns this fuel in its main engines during launch and ascent


EVA: extravehicular activity; common term for spacewalks and other journeys outside the protection of a spacecraft

forward: near or at the front of an aircraft or other vessel

gimballed: attached so as to be able to swivel slightly back and forth while remaining horizontally fixed

GPC: general-purpose computer; on-board computer that provides control for the space shuttle and, in some cases, payloads; the shuttle has five GPCs

hygiene: cleanliness for health reasons

IMU: inertial measurement unit; keeps track of the shuttle's position relative to its launch point in latitude and longitude

JPL: Jet Propulsion Laboratory; NASA's centre for robotic exploration of the solar system; located near Pasadena, California

JSC: Johnson Space Center; NASA centre that coordinates all operations of shuttle missions except launch and landing; located in Houston, Texas

kilopascal: a unit of pressure equal to one thousand Newtons per square metre (abbreviation kPa)

KSC: Kennedy Space Center; NASA's shuttle launch and landing site at Cape Canaveral, Florida

MAX Q: maximum aerodynamic pressure; in a typical launch, the period during which the Shuttle is most affected by turbulence caused by the shuttle's motion through the atmosphere

MCC: Mission Control Center; NASA centre where all operations of the shuttle are coordinated during a mission; located at the Johnson Space Center in Houston, Texas

MECO: main engine cutoff; shutdown of the shuttle's main engines about eight minutes after launch; at this point, the orbiter is travelling fast enough to achieve orbit; pronounced "MEE-ko"

MET: mission elapsed time; the running time from liftoff through the entire mission

microbes: microscopic living things; bacteria are a form of microbes

microgravity: term used to describe the relative weightlessness of space; there is some gravity in space--force exerted by the planets, moons, and Sun--but it is too slight for people to notice without special instruments

NASA: National Aeronautics and Space Administration; U.S. agency set up in 1958 to carry out the non-military exploration of space; headquarters in Washington, DC

oceanographic: of the exploration and study of the worldÕs oceans

OMS: orbital maneuvering system; two engines that the orbiter uses to lower and raise its orbit during a mission; the OMS is also used to slow the orbiter down for re-entry; pronounced "ohms," not "O-M-S"

Orbiter: the main flying vehicle of the Shuttle where the crew work and live; it is reusable

oxidizer: something that causes the release of oxygen during a chemical reaction with another substance 

particles: a very tiny bit of matter

pressurized: to have the air pressure (e.g. of a can, chamber or vessel) artificially maintained at a specific level

propulsion: the act of propelling or driving something from one place to another

radiate: release or give off; for example, a car's radiator releases heat from the engine into the outside air so that the engine doesn't overheat

RCS: Reaction Control System; a series of 44 thrusters in various locations around the orbiter; the RCS allows the pilot to make small changes in the orbiter's location and position while in orbit

rehydrate: to add water or liquid back into a substance that previously had all of its moisture taken out of it

respiratory: having to do with breathing 

RMS: Remote Manipulator System; the robotic arm on the shuttle, also known as the Canadarm

RSLS: redundant set launch sequencer; a launch abort that occurs after main-engine start but prior to solid rocket booster ignition

RTLS: return to launch site; a launch-abort procedure in which the shuttle returns to the launch site for landing; used in case of an engine failure in the first 4 minutes and 20 seconds of flight

satellite: an object that is gravitationally bound to orbit another, larger object; the moon is a satellite of the Earth; human-made satellites are launched into orbit for communications and observation of the planet and outer space

spontaneous combustion: the act of burning without being exposed to heat or flame from an outside source

SRBs: each of two slender rockets attached to the side of the External Tank; the SRBs give the shuttle the extra boost it needs to get off the ground and into orbit; they use up all of their solid fuel in about two minutes

SSME: Space Shuttle Main Engine; the Orbiter has three main engines; they burn liquid hydrogen and liquid oxygen from the External Tank

STS: Space Transportation System; the entire space shuttle system, including the orbiter, external tank, and solid rocket boosters; the STS also includes the buildings, equipment, and people involved in assembling and launching the shuttle and recovering its parts after each mission

thrust: force exerted in one direction that sends an object in another direction, e.g., the forced ejection of gases from the rear of a rocket that propels the rocket forward 

TAL: trans-oceanic abort landing; a launch-abort procedure in which the shuttle lands in Africa or Europe; a TAL may be attempted when it's too late for the shuttle to return to the launch site but the shuttle has enough altitude and speed to cross the Atlantic Ocean.

turbine: machine in which the kinetic energy of a moving fluid is converted into mechanical power by the reaction of the fluid with revolving blades 

valve: a movable device that opens and closes to control the flow of liquid or gas through a pipe or other hollow passageway

Vernier engine: a small rocket engine that is used to make very fine adjustments in speed, direction, and position

WCS: waste collection system; the shuttle's toilet; it is much like a regular toilet, except that it has a negative-airflow system (similar to that on an airplane) that sucks all the waste to the bottom of the toilet