Basics of Space Flight

With the buzz generated by Chandrayaan-2,  the second lunar exploration mission developed by the Indian Space Research Organisation (ISRO), after Chandrayaan-1, here’s a Glossary on Basics of Space Flight to make oneself familiar with some common terms associated with a space exploration. 

 

Abort: To cancel or cut short a mission.

 

Accelerometer: A device that senses changes in speed along its axis.

 

Aeronautics: The science of building and operating vehicles for flight.

 

Air lock: A compartment separating areas a different environment, especially different air pressures, that is used for entry to and departure from a spacecraft.

 

Altimeter: A device that measures altitude above the surface of a planet or moon. Spacecraft altimeters work by timing the round trip of radio signals bounced off the surface.

 

Autopilot: A system or device that controls a vehicle's flight at a preset course and altitude.

 

Ballistics: The science that deals with the motion, behavior, appearance or modification of missiles acted upon by propellants, rifling, wind, gravity, temperature or other modifying conditions of force.

 

Bi-propellant: A rocket propellant consisting of two unmixed or uncombined chemicals (fuel and oxidizer) fed separately into the combustion chamber.

 

Boost: The extra power given to a rocket or space vehicle during liftoff, climb or flight, as with a booster rocket. Booster: The first stage of a missile or rocket.

 

Centrifugal force: A force which is directed away from the center of rotation.

 

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.

 

Control rocket: A vernier or other rocket used to control the attitude of, or slightly change the speed of, a spacecraft.

 

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).

 

Descent engine: The rocket used to power a spacecraft as it makes a controlled landing on the surface of a planet or moon.

 

Descent module: That part of a spacecraft that descends from orbit to the surface of a planet or moon.

 

Docking: The technique of connecting two or more spacecraft in space.

 

Downlink: The radio signal transmitted from a spacecraft to Earth.

 

Escape tower: A rocket-powered framework designed to separate spacecraft modules from their booster rockets in case of accident. Escape towers are mounted atop the spacecraft and jettisoned after launch.

 

Extravehicular activity: Action performed by an astronaut or cosmonaut outside a vehicle in space; a spacewalk.

 

Flyby spacecraft: A spacecraft which follows a continuous trajectory past a target object, never to be captured into an orbit. It must carry instruments that are capable of observing passing targets by compensating for the target's apparent motion.

 

Jet propulsion: Reaction propulsion in which the propulsion unit obtains oxygen from the air as distinguished from rocket propulsion in which the unit carries its own oxygen-producing material.

 

Lander spacecraft: A spacecraft designed to reach the surface of a planet or moon and survive long enough to telemeter data back to Earth.

 

Launch complex & pad: The complex of site, facilities and equipment used to launch a missile or space rocket. Lunch pad is the load-bearing base from which a rocket or spacecraft positioned on its launcher is fired.

 

Lunar roving vehicle: A battery powered wheeled vehicle used by Apollo astronauts to explore the lunar surface.

 

Mach: The ratio of the speed of a vehicle (or of a liquid or gas) to the local speed of sound.

 

Module: A self-contained unit of a spacecraft or space station which serves as a building block for the total structure.

 

Mono-propellant: A rocket propellant consisting of a single substance, especially a liquid containing both fuel and oxidizer, either combined or mixed together.

 

Motor: In spacecraft, a rocket that burns solid propellants.

 

Nautical mile: The distance spanned by one minute of arc in latitude, defined internationally as 1,852 meters (6,076.1033 feet).

 

Orbiter spacecraft: A spacecraft designed to travel to a distant planet or moon and enter orbit. It must carry a substantial propulsive capability to decelerate it at the right moment to achieve orbit insertion.

 

O-stage: Rocket boosters which operate during part of the burning time of the first stage of a launch vehicle to provide additional thrust.

 

Payload: Revenue-producing or useful cargo carried by a spacecraft; also, anything carried in a rocket or spacecraft that is not part of the structure, propellant, or guidance systems.

 

Pressure suit: A suit, with helmet attached, which is inflated to provide body pressure and air, worn by the crew of certain spacecraft and aircraft which fly at great altitudes.

 

Propellant: A chemical or chemical mixture burned to create the thrust for a rocket or spacecraft.
Retrorocket: A rocket fired to reduce the speed of a spacecraft.

 

Rocket: A missile or vehicle propelled by the combustion of a fuel and a contained oxygen supply. The forward thrust of a rocket results when exhaust products are ejected from the tail.

 

Rover: A rover (or sometimes planetary rover) is a space exploration vehicle designed to move across the surface of a planet or other celestial body.

 

Sounding rocket: A research rocket used to obtain data from the upper atmosphere.

 

Space: The universe beyond Earth's atmosphere. The boundary at which the atmosphere ends and space begins is not sharp but starts at approximately 100 miles above Earth's surface.

 

Spacecraft: A piloted or unpiloted vehicle designed for travel in space.

 

Spacecraft clock: A counter maintained by the command & data subsystem. It meters the passing of time during the life of the spacecraft, and regulates nearly all activity within the spacecraft systems.

 

Space platform: A large artificial satellite conceived as a habitable base in space with scientific, exploratory or military applications. A space station.

 

Space station: An orbiting spacecraft designed to support human activity for an extended time.

 

Sustainer engine: An engine that maintains propulsion of a launch vehicle once it has discarded its boosters.

 

Transponder: A device that transmits a response signal automatically when activated by an incoming signal.

 

Uplink: The radio signal transmitted to a spacecraft from Earth.

 

(Source: https://www.scss.tcd.ie/Stephen.Farrell/ipn/background/Braeunig/glossary.htm; https://spaceplace.nasa.gov/glossary/en/)