Type	Fewer Letters	More Letters
Acronym	301	Cr-Ni stainless steel (X10CrNi18-8): high tensile strength, good ductility
Acronym	304L	Cr-Ni stainless steel with low carbon (X2CrNi19-11): corrosion-resistant with good stress relief properties
Acronym	30X	SpaceX-proprietary carbon steel formulation (*"Thirty-X", "Thirty-Times"*)
Acronym	A-train	[Afternoon Train satellite constellation](https://en.wikipedia.org/wiki/A-train_%28satellite_constellation%29)
Acronym	ABS	[Acrylonitrile Butadiene Styrene](https://en.wikipedia.org/wiki/Acrylonitrile_butadiene_styrene), hard plastic Asia Broadcast Satellite, commsat operator
Acronym	ACES	[Advanced Cryogenic Evolved Stage](https://en.wikipedia.org/wiki/Advanced_Cryogenic_Evolved_Stage) [Advanced Crew Escape Suit](https://en.wikipedia.org/wiki/Advanced_Crew_Escape_Suit)
Acronym	ACS	Attitude Control System
Acronym	ACST	Australian Central Standard Time (UTC+9.5), Northern Territory and South Australia
Acronym	ADCS	Attitude Determination and Control System
Acronym	ADELINE	[Advanced Expendable Launcher with Innovative Engine Economy](https://en.wikipedia.org/wiki/Adeline_\(rocket_stage\)), Airbus Safran's returnable-engine first stage
Acronym	ADEPT	Adaptive Deployable Entry and Placement Technology carbon-fiber heatshield
Acronym	AEB	Agencia Espaciale Brasileira
Acronym	AFB	[Air Force Base](https://en.wikipedia.org/wiki/Military_airbase)
Acronym	AFRL	(US) Air Force Research Laboratory
Acronym	AFSS	Automated Flight Safety System
Acronym	AFTS	Autonomous Flight Termination System, see FTS
Acronym	AGL	Above Ground Level
Acronym	AGuS	Automatic Guidance System
Acronym	AHRS	Attitude and Heading Reference System
Acronym	AIS	[Automatic Identification System](https://en.wikipedia.org/wiki/Automatic_Identification_System)
Acronym	AIT	Assembly, Integration and Testing
Acronym	AJR	Aerojet Rocketdyne
Acronym	AoA	Angle of Attack
Acronym	AoE	Area of Effect
Acronym	AOS	Acquisition of Signal
Acronym	APOD	NASA's Astronomy Picture Of the Day
Acronym	AR	Area Ratio (between rocket engine nozzle and bell) Aerojet Rocketdyne Augmented Reality real-time processing Anti-Reflective optical coating
Acronym	AR-1	AR's [RP-1/LOX engine](https://en.wikipedia.org/wiki/Aerojet_Rocketdyne#AR1) proposed to replace RD-180
Acronym	ARM	Asteroid Redirect Mission Advanced RISC Machines, embedded processor architecture
Acronym	ARMD	Aeronautics Research Mission Directorate, NASA
Acronym	ASAP	Aerospace Safety Advisory Panel, NASA Arianespace System for Auxiliary Payloads
Acronym	ASAT	[Anti-Satellite weapon](https://en.wikipedia.org/wiki/Anti-satellite_weapon)
Acronym	ASDBC	Autonomous Spaceport Drone Bouncy Castle, for soft landings
Acronym	ASDS	Autonomous Spaceport Drone Ship (landing platform)
Acronym	ASIC	Application-Specific Integrated Circuit
Acronym	ASL	[Airbus Safran Launchers](https://en.wikipedia.org/wiki/Airbus_Safran_Launchers), builders of the Ariane 6
Acronym	ASOG	A Shortfall of Gravitas, landing ~~barge~~ ship
Acronym	ASS	Acronyms Seriously Suck
Acronym	ATA	Anthropomorphic Test Article (*Ripley*), flown on DM-1
Acronym	ATK	Alliant Techsystems, predecessor to Orbital ATK
Acronym	ATP	Acceptance Test Procedure
Acronym	ATV	Advanced Technology Vehicle, a launcher for sub-orbital experiments
Acronym	ATV	[Automated Transfer Vehicle](https://en.wikipedia.org/wiki/Automated_Transfer_Vehicle), ESA cargo craft
Acronym	AVI	Avionics Operator
Acronym	BARGE	[Big-Ass Remote Grin Enhancer](https://twitter.com/IridiumBoss/status/864579184483590144) coined by @IridiumBoss, see ASDS
Acronym	BCC	(Iron/steel) [Body-Centered Cubic](https://en.wikipedia.org/wiki/Allotropes_of_iron) crystalline structure Backup Control Center, MSFC (for ISS operations if Houston is inoperative)
Acronym	BE-3	Blue Engine 3 hydrolox rocket engine, developed by Blue Origin (2015), 490kN
Acronym	BE-4	Blue Engine 4 methalox rocket engine, developed by Blue Origin (2018), 2400kN
Acronym	BE-4U	Blue Engine 4 methalox rocket engine, Blue Origin (2018), vacuum-optimized
Acronym	BEAM	[Bigelow Expandable Activity Module](https://en.wikipedia.org/wiki/Bigelow_Expandable_Activity_Module)
Acronym	BECO	Booster Engine Cut-Off
Acronym	BEO	Beyond Earth Orbit
Acronym	BFB	Big Falcon Booster (see BFR)
Acronym	BFG	Big Falcon Grasshopper ("Locust"), BFS test article
Acronym	BFR	Big Falcon Rocket (2018 rebiggened edition) Yes, the F stands for something else; no, you're not the first to notice
Acronym	BFS	Big Falcon Spaceship (see BFR)
Acronym	BFT	Big Falcon Tanker (see BFS)
Acronym	BLEO	Beyond Low Earth Orbit, in reference to human spaceflight
Acronym	BN	(Starship/Superheavy) Booster Number
Acronym	BO	Blue Origin (*Bezos Rocketry*)
Acronym	BPC	BFR/ITS/MCT Planetary Colonizer, 2017 design
Acronym	BSS	Back-Shell Separation, event during Curiosity EDL
Acronym	C3	[Characteristic Energy](https://en.wikipedia.org/wiki/Characteristic_energy) above that required for escape
Acronym	CAA	Crew Access Arm, for transfer of crew on a launchpad
Acronym	CAP	[Combat Air Patrol](https://en.wikipedia.org/wiki/Combat_air_patrol)
Acronym	CARE	Crew module Atmospheric Re-entry Experiment
Acronym	CATO	Catastrophe At Take Off, see RUD
Acronym	CBC	Common Booster Core Canadian Broadcasting Corporation
Acronym	CBM	[Common Berthing Mechanism](https://en.wikipedia.org/wiki/Common_Berthing_Mechanism)
Acronym	CC	Commercial Crew program Capsule Communicator (ground support)
Acronym	CCAFS	Cape Canaveral Air Force Station
Acronym	CCAM	Collision and Contaminance Avoidance Maneuver
Acronym	CCDEV	[Commercial Crew DEVelopment](https://en.wikipedia.org/wiki/Commercial_Crew_Development)
Acronym	CCiCap	[Commercial Crew Integrated Capability](https://en.wikipedia.org/wiki/Commercial_Crew_Development#Commercial_Crew_integrated_Capability)
Acronym	CCtCap	[Commercial Crew Transportation Capability](https://en.wikipedia.org/wiki/Commercial_Crew_Development#Commercial_Crew_Transportation_Capability_.28CCtCap.29)
Acronym	Cd	[Coefficient of Drag](https://en.wikipedia.org/wiki/Drag_coefficient)
Acronym	CDR	Critical Design Review (As 'Cdr') Commander
Acronym	CELSS	Closed Ecological Life Support System
Acronym	CF	Carbon Fiber (Carbon Fibre) composite material CompactFlash memory storage for digital cameras
Acronym	CFD	Computational Fluid Dynamics
Acronym	CFRP	Carbon-Fibre-Reinforced Polymer
Acronym	CLCDr	Central Launch Command Director
Acronym	CLD	Commercial Low-orbit Destination(s)
Acronym	CLPS	[Commercial Lunar Payload Services](https://en.wikipedia.org/wiki/Commercial_Lunar_Payload_Services)
Acronym	CME	Coronal Mass Ejection
Acronym	CMG	Control Moment Gyroscope, RCS for the Station
Acronym	CMP	Command Module Pilot (especially for Apollo)
Acronym	CNC	Computerized Numerical Control, for precise machining or measuring
Acronym	CNES	Centre National d'Etudes Spatiales, space agency of France
Acronym	CNSA	Chinese National Space Administration
Acronym	CoG	Center of Gravity (see CoM)
Acronym	CoM	Center of Mass
Acronym	CONUS	[Contiguous United States](https://en.wikipedia.org/wiki/Contiguous_United_States)
Acronym	CoP	Center of Pressure (see CoG)
Acronym	COPV	[Composite Overwrapped Pressure Vessel](https://en.wikipedia.org/wiki/Composite_overwrapped_pressure_vessel)
Acronym	COSPAR	Committee for Space Research
Acronym	COTS	[Commercial Orbital Transportation Services contract](https://www.nasa.gov/cots) Commercial/Off The Shelf
Acronym	CREAM	Cosmic Radiation Effects and Activation Monitor, Station experiment slated for CRS-12
Acronym	CRS	[Commercial Resupply Services contract with NASA](http://www.nasa.gov/mission_pages/station/structure/launch/)
Acronym	CRS2	Commercial Resupply Services, second round contract; expected to start 2019
Acronym	CSA	Canadian Space Agency
Acronym	CST	(Boeing) Crew Space Transportation capsules Central Standard Time (UTC-6)
Acronym	CTB	Cargo Transfer Bag
Acronym	CUCU	COTS UHF Communications Unit (ISS-to-Dragon radio)
Acronym	C^(3)PO	Commercial Crew and Cargo Program Office, NASA
Acronym	DARPA	(Defense) Advanced Research Projects Agency, DoD
Acronym	DCS	Decompression Sickness *Digital Combat Simulator*, the flight simulator
Acronym	DCSS	Delta Cryogenic Second Stage
Acronym	DIVH	Delta IV Heavy
Acronym	DLR	Deutsches Zentrum fuer Luft und Raumfahrt (German Aerospace Center), Cologne
Acronym	DMLS	[Selective Laser Melting](https://en.wikipedia.org/wiki/Direct_metal_laser_sintering) additive manufacture, also Direct Metal Laser Sintering
Acronym	DoD	US Department of Defense
Acronym	DP	[Dynamic Positioning](https://en.wikipedia.org/wiki/Dynamic_positioning) ship navigation systems
Acronym	DPL	Downrange Propulsive Landing (on an ocean barge/ASDS)
Acronym	DRL	Downrange Landing
Acronym	DRO	[Distant Retrograde Orbit](http://ccar.colorado.edu/asen5050/projects/projects_2013/Johnson_Kirstyn/finalorbit.html)
Acronym	DRRPL	Down-Range Retro-Propulsive Landing
Acronym	DRRRPL	Down-Range Re-entry and Retro-Propulsive Landing
Acronym	DRRRRPL	Down-Range Retrograde, Re-entry, and Retro-Propulsive Landing maneuver
Acronym	DRRRRRRPL	Down-Range Retrograde RCS Rotation, Re-entry, and Retro-Propulsive Landing maneuver
Acronym	DSG	NASA [Deep Space Gateway](https://www.nasa.gov/feature/deep-space-gateway-to-open-opportunities-for-distant-destinations), proposed for lunar orbit
Acronym	DSH	Deep Space Habitat
Acronym	DSN	Deep Space Network
Acronym	DST	NASA Deep Space Transport operating from the proposed DSG
Acronym	DTN	Delay/Disruption Tolerant Networking
Acronym	DUR	Delightful Unscheduled Recovery
Acronym	DVIC	Digital Voice Inter-Communications subsystem between consoles in launch/mission control
Acronym	E2E	Earth-to-Earth (suborbital flight)
Acronym	EA	Environmental Assessment
Acronym	EAR	Export Administration Regulations, covering technologies that are not solely military
Acronym	ECLSS	Environment Control and Life Support System
Acronym	EDAC	Error Detection And Correction in integrated circuits
Acronym	EDL	Entry/Descent/Landing
Acronym	EDRS	European Data Relay System
Acronym	EELV	[Evolved Expendable Launch Vehicle](https://en.wikipedia.org/wiki/Evolved_Expendable_Launch_Vehicle)
Acronym	EELV2	Second phase of the EELV program
Acronym	EGSE	Electrical Ground Support Equipment
Acronym	EHT	Event Horizon Telescope
Acronym	EIS	Environmental Impact Statement
Acronym	ELC	EELV Launch Capability contract ("assured access to space")
Acronym	ELDRS	Enhanced Low Dose Rate Sensitivity (lower-intensity radiation causing more damage)
Acronym	ELE	[Extinction-Level Event](http://www.imdb.com/title/tt0120647/)
Acronym	ELT	Extremely Large Telescope, under construction in Chile
Acronym	EM-1	[Exploration Mission 1](https://en.wikipedia.org/wiki/Exploration_Mission_1), Orion capsule; planned for launch on SLS
Acronym	EML1	Earth-Moon Lagrange point 1
Acronym	EMU	Extravehicular Mobility Unit (spacesuit)
Acronym	EOI	Earth Orbital Insertion maneuver
Acronym	EOL	End Of Life
Acronym	ERP	Effective Radiated Power
Acronym	ERV	Earth Return Vehicle
Acronym	ESA	European Space Agency
Acronym	ESM	European Service Module, component of the Orion capsule
Acronym	ESO	[European Southern Observatory](https://en.wikipedia.org/wiki/European_Southern_Observatory), builders of the VLT and EELT
Acronym	ESPA	EELV Secondary Payload Adapter standard for attaching to a second stage
Acronym	ETLA	Extended Three Letter Acronym (4+ letters)
Acronym	ETO	Earth-To-Orbit transport of materials
Acronym	ETOV	Earth To Orbit Vehicle (common parlance: "rocket")
Acronym	EUS	Exploration Upper Stage
Acronym	EVA	Extra-Vehicular Activity
Acronym	EVEEGA	Earth/Venus/Earth/Earth Gravity Assist
Acronym	EVS	Extra-Vehicular Suit (see EVA)
Acronym	F1	Rocketdyne-developed rocket engine used for Saturn V SpaceX Falcon 1 (obsolete small-lift vehicle)
Acronym	F9EFT	Falcon 9 v1.2.1, Even Fuller Thrust (uprated, 2016)
Acronym	F9FT	Falcon 9 Full Thrust *or* Upgraded Falcon 9 *or* v1.2
Acronym	F9R	Falcon 9 Reusable, test vehicles for development of landing technology
Acronym	FAA	Federal Aviation Administration
Acronym	FAA-AST	Federal Aviation Administration [Administrator for Space Transportation](http://www.faa.gov/about/office_org/headquarters_offices/ast/)
Acronym	FAP	Fairing Acoustic Protection
Acronym	FAR	[Federal Aviation Regulations](https://en.wikipedia.org/wiki/Federal_Aviation_Regulations)
Acronym	FCC	Federal Communications Commission (Iron/steel) [Face-Centered Cubic](https://en.wikipedia.org/wiki/Allotropes_of_iron) crystalline structure
Acronym	FFSC	Full-Flow Staged Combustion
Acronym	FFSCC	Full Flow Staged Combustion Cycle
Acronym	FFSS	Firefly Space Systems
Acronym	FISO	[Future In-Space Operations teleconferences](http://spirit.as.utexas.edu/%7Efiso/archivelist.htm)
Acronym	FLEA	Four Letter Extended Acronym (see ETLA)
Acronym	FLP	First Launch Pad at Satish Dhawan Space Centre, operational since 1990s
Acronym	FLW	The Following (as found on NOTAMs)
Acronym	FMEA	[Failure-Mode-and-Effects Analysis](https://en.wikipedia.org/wiki/Failure_mode_and_effects_analysis)
Acronym	FOD	[Foreign Object Damage](https://en.wikipedia.org/wiki/Foreign_object_damage) / Debris
Acronym	FOIA	(US) [Freedom of Information Act](https://www.foia.gov/)
Acronym	FoS	Factor of Safety for design of high-stress components (see COPV)
Acronym	FPIP	Flight Planning Integration Panel, FPWG
Acronym	FPWG	Flight Planning Work Group for the Space Station
Acronym	FRAM	Flight Releasable Attachment Mechanism
Acronym	FRL	Fire-Retardant Latex (White rocket paint)
Acronym	FRSC	Fuel-Rich Staged Combustion
Acronym	FSS	Fixed Service Structure at LC-39
Acronym	FSW	[Friction-Stir Welding](https://en.wikipedia.org/wiki/Friction_stir_welding)
Acronym	FTBA	"Flip This ~~Bi-~~ Booster Around" boostback burn, part of first-stage landing procedure
Acronym	FTS	Flight Termination System
Acronym	FTV	Flight Test Vehicle (see hopper)
Acronym	G-LOC	G-force-induced Loss Of Consciousness
Acronym	GAO	(US) Government Accountability Office
Acronym	GCR	Galactic Cosmic Rays, incident from outside the star system
Acronym	GEO	Geostationary Earth Orbit (35786km)
Acronym	GeV	Giga-Electron-Volts, measure of energy for particles
Acronym	GLOW	Gross Lift-Off Weight
Acronym	GNC	Guidance/Navigation/Control
Acronym	GNSS	Global Navigation Satellite System(s)
Acronym	GOX	Gaseous Oxygen (contrast LOX)
Acronym	GPC	General-Purpose Computer (the [IBM AP-101](https://en.wikipedia.org/wiki/IBM_AP-101) on Shuttle)
Acronym	GRB	Gamma-Ray Burst
Acronym	GSE	Ground Support Equipment
Acronym	GSFC	Goddard Space Flight Center, Maryland
Acronym	GSLV	(India's) Geostationary Launch Vehicle
Acronym	GSLV	Geosynchronous Satellite Launch Vehicle
Acronym	GSO	Geosynchronous Orbit (any Earth orbit with a 24-hour period) Guang Sheng Optical telescopes
Acronym	GTC	Gran Telescopio Canarias, Spain
Acronym	GTE	Ground Test Equipment (as opposed to Ground Support Equipment, which would support a launch)
Acronym	GTO	[Geosynchronous Transfer Orbit](http://www.planetary.org/blogs/jason-davis/20140116-how-to-get-a-satellite-to-gto.html)
Acronym	GTO-1500	Geosynchronous Transfer Orbit (185 x 35786km, 0 inclination), requires 1500m/s to reach GEO
Acronym	GTO-1800	Geosynchronous Transfer Orbit (185 x 35786km, 27-degree inclination), requires 1800m/s to reach GEO
Acronym	H1	First half of the year/month
Acronym	H2	Molecular hydrogen Second half of the year/month
Acronym	HALO	Habitation and Logistics Outpost
Acronym	HAN	[Hydroxylammonium Nitrate](https://en.wikipedia.org/wiki/Hydroxylammonium_nitrate)
Acronym	HASC	(US) House (of Representatives) Armed Services Committee
Acronym	HCO	Heliocentric Orbit
Acronym	HDEV	High Definition Earth Viewing experiment, fitted to ISS
Acronym	HEEO	Highly Elliptical Earth Orbit
Acronym	HEMO	Highly Elliptical Mars Orbit
Acronym	HEO	High Earth Orbit (above 35780km) Highly Elliptical Orbit Human Exploration and Operations (see HEOMD)
Acronym	HEOMD	Human Exploration and Operations Mission Directorate, NASA
Acronym	HERA	[Human Exploration Research Analog](https://www.nasa.gov/analogs/hera)
Acronym	HEU	Highly-Enriched Uranium, fissile material with a high percentage of U-235 ("boom stuff")
Acronym	HIAD	Hypersonic Inflatable Aerodynamic Decelerator (derived from LDSD)
Acronym	HIF	Horizontal Integration Facility
Acronym	HIL	Hardware in the Loop, see HITL
Acronym	HITL	Hardware in the Loop Human in the Loop
Acronym	HLC-39A	**Historic** Launch Complex 39A, Kennedy (Saturn V, Shuttle, SpaceX F9/Heavy)
Acronym	HLLV	Heavy Lift Launch Vehicle (20-50 tons to LEO)
Acronym	HLS	[Human Landing System](https://en.wikipedia.org/wiki/Artemis_program#Human_Landing_System) (Artemis)
Acronym	HLV	Heavy Lift Launch Vehicle (20-50 tons to LEO)
Acronym	HPFTP	High Pressure Fuel Turbopump
Acronym	HPOTP	High Pressure Oxidiser Turbopump
Acronym	HPTP	High Pressure Turbopump
Acronym	HRLV	[ISRO] Human Rated Launch Vehicle
Acronym	HSF	Human Space Flight
Acronym	HST	Hubble Space Telescope
Acronym	HTHL	Horizontal Takeoff, Horizontal Landing (*Skylon* (proposed))
Acronym	HTPB	Hydroxyl-terminated polybutadiene, solid propellant
Acronym	HTS	Horizontal Test Stand
Acronym	HUD	Head(s)-Up Display, often implemented as a projection
Acronym	IAC	International Astronautical Congress, annual meeting of IAF members In-Air Capture of space-flown hardware
Acronym	IAF	[International Astronautical Federation](http://www.iafastro.org/) Indian Air Force Israeli Air Force
Acronym	IANARS	I Am Not A Rocket Scientist, but...
Acronym	ICBM	Intercontinental Ballistic Missile
Acronym	ICPS	Interim Cryogenic Propulsion Stage
Acronym	ICT	Interplanetary Colonial Transport (see ITS)
Acronym	IDA	[International Docking Adapter](https://en.wikipedia.org/wiki/International_Docking_Adapter) [International Dark-Sky Association](https://en.wikipedia.org/wiki/International_Dark-Sky_Association)
Acronym	IDSN	Indian Deep Space Network
Acronym	IDSS	[International Docking System Standard](https://en.wikipedia.org/wiki/International_Docking_System_Standard)
Acronym	IFA	In-Flight Abort test
Acronym	IFR	[Instrument Flight Rules](https://en.wikipedia.org/wiki/Instrument_flight_rules)
Acronym	IIP	Instantaneous Impact Point (where a payload would land if Stage 2 failed)
Acronym	ILC	Initial Launch Capability
Acronym	ILS	[International Launch Services](https://en.wikipedia.org/wiki/International_Launch_Services) [Instrument Landing System](https://en.wikipedia.org/wiki/Instrument_landing_system)
Acronym	IM	Initial Mass deliverable to a given orbit, without accounting for fuel
Acronym	IMGTO	Initial Mass deliverable to GTO, see IM
Acronym	IMLEO	Initial Mass deliverable to LEO, see IM
Acronym	IMRS	International Mars Research Station (proposed by Blue Mars)
Acronym	IMU	Inertial Measurement Unit
Acronym	INS	[Inertial Navigation System](https://en.wikipedia.org/wiki/Inertial_navigation_system)
Acronym	IRFNA	Inhibited Red Fuming Nitric Acid, mixed with hydrogen fluoride for stability
Acronym	IRNSS	Indian Regional Navigation Satellite System
Acronym	IRT	Independent Review Team
Acronym	ISAP	In-Situ Air Production
Acronym	ISC	Institutional Services Contract, under which a private company provides support services to NASA/USAF
Acronym	ISECG	International Space Exploration Coordinating Group
Acronym	ISEP	In-Situ Electricity/Energy Production
Acronym	ISFP	In-Situ Food Production
Acronym	ISL	Inter-Satellite Link communication between satellites in orbit
Acronym	Isp	Specific impulse (as explained by [Scott Manley](https://www.youtube.com/watch?v=nnisTeYLLgs) on YouTube) Internet Service Provider
Acronym	ISPP	In-Situ Propellant Production
Acronym	ISPR	International Standard Payload Rack
Acronym	ISRO	Indian Space Research Organisation
Acronym	ISRU	[In-Situ Resource Utilization](https://en.wikipedia.org/wiki/In_situ_resource_utilization)
Acronym	ISSP	[International Space Station Program](https://en.wikipedia.org/wiki/International_Space_Station_program), the legal framework for ISS maintenance
Acronym	ISTRAC	ISRO Telemetry, Tracking and Command Network
Acronym	ISW	(US) Institute for the Study of War
Acronym	ISWP	In-Situ Water Production
Acronym	ITAR	(US) International Traffic in Arms Regulations
Acronym	ITN	Interplanetary Transport Network
Acronym	ITS	Interplanetary Transport System (2016 oversized edition) (see MCT) [Integrated Truss Structure](https://en.wikipedia.org/wiki/Integrated_Truss_Structure)
Acronym	ITU	International Telecommunications Union, responsible for coordinating radio spectrum usage
Acronym	IVA	Intra-Vehicular Activity
Acronym	IVS	Intra-Vehicular Suit (see IVA)
Acronym	JATO	[Jet-Assisted Take-Off](https://en.wikipedia.org/wiki/JATO), used by aircraft on short runways
Acronym	JAXA	Japan Aerospace eXploration Agency
Acronym	JCSAT	Japan Communications Satellite series, by JSAT Corp
Acronym	JOI	Jovian Orbital Insertion maneuver
Acronym	JPADS	Air Force [Joint Precision Air Drop System](https://en.wikipedia.org/wiki/Joint_Precision_Airdrop_System), possible parafoils for fairing recovery
Acronym	JPL	Jet Propulsion Lab, California
Acronym	JRTI	Just Read The Instructions, ~~Pacific~~ Atlantic landing ~~barge~~ ship
Acronym	JSC	Johnson Space Center, Houston
Acronym	JWST	James Webb infra-red Space Telescope
Acronym	KARI	Korean Aerospace Research Institute
Acronym	KOS	Keep Out Sphere, 200m radius from ISS Kerbal Operating System, the KSP in-game rocket OS
Acronym	KSC	Kennedy Space Center, Florida
Acronym	KSP	*Kerbal Space Program*, the rocketry simulator
Acronym	L1	[Lagrange Point](https://en.wikipedia.org/wiki/Lagrangian_point) 1 of a two-body system, between the bodies
Acronym	L2	[Lagrange Point](https://en.wikipedia.org/wiki/Lagrangian_point) 2 ([Sixty Symbols](https://www.youtube.com/watch?v=mxpVbU5FH0s) video explanation) Paywalled section of the NasaSpaceFlight forum
Acronym	L3	[Lagrange Point](https://en.wikipedia.org/wiki/Lagrangian_point) 3 of a two-body system, opposite L2
Acronym	L4	"Trojan" [Lagrange Point](https://en.wikipedia.org/wiki/Lagrangian_point) 4 of a two-body system, 60 degrees ahead of the smaller body
Acronym	L5	"Trojan" [Lagrange Point](https://en.wikipedia.org/wiki/Lagrangian_point) 5 of a two-body system, 60 degrees behind the smaller body
Acronym	LAS	Launch Abort System
Acronym	LBT	Large Binocular Telescope, Arizona
Acronym	LC-13	Launch Complex 13, Canaveral (SpaceX Landing Zone 1)
Acronym	LC-39A	Launch Complex 39A, Kennedy (SpaceX F9/Heavy)
Acronym	LCC	Launch Control Center
Acronym	LCH4	Liquid Methane
Acronym	LDRO	Lunar Distant Retrograde Orbit
Acronym	LDSD	Low-Density Supersonic Decelerator test vehicle
Acronym	LEM	(Apollo) [Lunar Excursion Module](https://en.wikipedia.org/wiki/Apollo_Lunar_Module) (also Lunar Module)
Acronym	LEO	Low Earth Orbit (180-2000km) Law Enforcement Officer (most often mentioned during transport operations)
Acronym	LES	Launch Escape System
Acronym	LEU	Low-Enriched Uranium, fissile material that's not explosively so
Acronym	LH2	Liquid Hydrogen
Acronym	LIDAR	[Light Detection and Ranging](https://en.wikipedia.org/wiki/Lidar)
Acronym	LIGO	Laser Interferometer Gravitational-wave Observatory
Acronym	LISA	Laser Interferometer Space Antenna
Acronym	LLCC	(SpaceX) Launch and Landing Control Center, Port Canaveral
Acronym	LLO	Low Lunar Orbit (below 100km)
Acronym	LMO	Low Mars Orbit
Acronym	LMP	(Apollo) Lunar Module Pilot
Acronym	LN2	Liquid Nitrogen
Acronym	LNG	Liquefied Natural Gas
Acronym	LO2	Liquid Oxygen (more commonly LOX)
Acronym	LOC	Loss of Crew
Acronym	LOLI	Limited-Operational-Life Item (lasts a number of cycles before needing replacement)
Acronym	LOM	Loss of Mission
Acronym	LOP-G	Lunar Orbital Platform - Gateway, formerly DSG
Acronym	LOS	Loss of Signal | |Line of Sight
Acronym	LOV	Loss Of Vehicle
Acronym	LOX	Liquid Oxygen
Acronym	LPFTP	Low Pressure Fuel Turbopump
Acronym	LPG	Liquified Petroleum Gas [Liquified Pigeon Guts](https://www.reddit.com/r/SpaceXLounge/comments/6to7zk/how_many_pigeons_can_a_falcon_9_launch_into_leo/dlmmcg3/)
Acronym	LPOTP	Low Pressure Oxidiser Turbopump
Acronym	LPSC	Liquid Propulsion Systems Centre
Acronym	LPTP	Low Pressure Turbopump
Acronym	LRR	Launch Readiness Review
Acronym	LSA	Launch Services Agreement
Acronym	LSP	Launch Service Provider (US) [Launch Service Program](https://www.nasa.gov/content/lsp-overview)
Acronym	LUT	Launch Umbilical Tower Look-Up Table
Acronym	LV	Launch Vehicle (common parlance: "rocket"), see ETOV
Acronym	LZ	Landing Zone
Acronym	LZ-1	Landing Zone 1, Cape Canaveral (see LC-13)
Acronym	LZ-2	Landing Zone 2, Vandenberg (see SLC-4W)
Acronym	MAF	Michoud Assembly Facility, Louisiana
Acronym	MAV	*Mars Ascent Vehicle* ([possibly fictional](https://en.wikipedia.org/wiki/The_Martian_\(Weir_novel\)))
Acronym	MaxQ	Maximum aerodynamic pressure
Acronym	MBA	~~Moonba-~~ Mars Base Alpha
Acronym	MCC	Mission Control Center Mars Colour Camera
Acronym	MCC-H	Nasa's Mission Control Center (Houston), Texas
Acronym	MCC-M	Roscosmos' Mission Control Center (Moscow), Russia
Acronym	MCC-X	Mission Control Center (SpaceX), Hawthorne, California
Acronym	MCF	Main Component Failure
Acronym	MCP	Mechanical Counterpressure spacesuit
Acronym	MCT	Mars Colonial Transporter (see ITS)
Acronym	MDA	[Missile Defense Agency](https://en.wikipedia.org/wiki/Missile_Defense_Agency) [MacDonald, Dettwiler and Associates](https://en.wikipedia.org/wiki/MacDonald,_Dettwiler_and_Associates), owner of SSL, builder of Canadarm
Acronym	MECO	Main Engine Cut-Off [MainEngineCutOff](https://mainenginecutoff.com/) podcast
Acronym	MegaROSA	Multi-element Roll-Out Solar Array
Acronym	MENA	Middle East and North Africa, Morocco to Iran
Acronym	MEO	Medium Earth Orbit (2000-35780km)
Acronym	MEOP	Maximum Expected Operating Pressure
Acronym	MER	Mars Exploration Rover (Spirit/Opportunity) Mission Evaluation Room in back of Mission Control
Acronym	MES	Main Engine Start
Acronym	MET	[Mission Elapsed Time](https://en.wikipedia.org/wiki/Mission_Elapsed_Time)
Acronym	MeV	Mega-Electron-Volts, measure of energy for particles
Acronym	MFR	Medium ~~Fu-~~ Falcon Rocket (Falcon 9/Heavy), contrast BFR Manipulator Foot Restraint, support equipment for Hubble servicing
Acronym	MGS	Mars Global Surveyor satellite
Acronym	MHI	Mitsubishi Heavy Industries, builder of the H-IIA
Acronym	MLLV	Medium Lift Launch Vehicle (2-20 tons to LEO)
Acronym	MLP	Mobile Launcher Platform
Acronym	MLV	Medium Lift Launch Vehicle (2-20 tons to LEO)
Acronym	MMH	Mono-Methyl Hydrazine, (CH3)HN-NH2; part of NTO/MMH hypergolic mix
Acronym	MMOD	Micro-Meteoroids and Orbital Debris
Acronym	MMSEV	[Multi-Mission Space Exploration Vehicle](https://www.nasa.gov/exploration/technology/space_exploration_vehicle/index.html)
Acronym	MMT	Multiple-Mirror Telescope, Arizona Multiscale Median Transform, an alternative to wavelet image compression
Acronym	MMU	[Manned Maneuvering Unit](https://en.wikipedia.org/wiki/Manned_Maneuvering_Unit), untethered spacesuit propulsion equipment
Acronym	MOI	Mars Orbital Insertion maneuver
Acronym	MOM	Mars Orbiter Mission
Acronym	MON	Mixed Oxides of Nitrogen
Acronym	MPLM	[Multi-Purpose Logistics Module](https://en.wikipedia.org/wiki/Multi-Purpose_Logistics_Module) formerly used to supply ISS
Acronym	MRO	Mars Reconnaisance Orbiter Maintenance, Repair and/or Overhaul
Acronym	MSFC	Marshall Space Flight Center, Alabama
Acronym	MSL	Mars Science Laboratory (Curiosity) Mean Sea Level, reference for altitude measurements
Acronym	mT	~~Milli-~~ *Metric* Tonnes
Acronym	MZ	(Yusaku) Maezawa, first confirmed passenger for BFR
Acronym	N1	Raketa Nositel-1, Soviet super-heavy-lift ("Russian Saturn V")
Acronym	NA	New Armstrong, super-heavy lifter proposed by Blue Origin
Acronym	NAC	NASA Advisory Council
Acronym	NAP	No-Acronym Policy
Acronym	NAS	National Airspace System [Naval Air Station](https://en.wikipedia.org/wiki/Naval_air_station)
Acronym	NAVIC	Navigation with Indian Constellation
Acronym	NDA	Non-Disclosure Agreement
Acronym	NdGT	Neil deGrasse Tyson
Acronym	NDS	[NASA Docking System](https://en.wikipedia.org/wiki/NASA_Docking_System), implementation of the international standard
Acronym	NEO	Near-Earth Object
Acronym	NEPA	(US) [National Environmental Policy Act]https://en.wikipedia.org/wiki/National_Environmental_Policy_Act) 1970
Acronym	NERVA	Nuclear Engine for Rocket Vehicle Application (proposed engine design)
Acronym	NET	No Earlier Than
Acronym	NEV	Nuclear Electric Vehicle propulsion
Acronym	NG	New Glenn, two/three-stage orbital vehicle by Blue Origin Natural Gas (as opposed to pure methane) Northrop Grumman, aerospace manufacturer
Acronym	NGIS	Northrop Grumman Innovation Systems, formerly OATK
Acronym	NGLLC	Northrop-Grumman [Lunar Lander Challenge](https://en.wikipedia.org/wiki/Lunar_Lander_Challenge), 2006-09
Acronym	NGSO	Non-Geostationary Orbit
Acronym	NIAC	NASA Innovative Advanced Concepts program
Acronym	NICER	[Neutron star Interior Composition ExploreR](http://www.nasa.gov/mission_pages/station/research/experiments/1966.html), an ISS experiment
Acronym	NLS	NASA Launch Services contracts
Acronym	NOAA	National Oceanic and Atmospheric Administration, responsible for US ~~generation~~ monitoring of the climate
Acronym	NORAD	North American Aerospace Defense command
Acronym	NOTAM	[Notice to Air Missions](https://en.wikipedia.org/wiki/NOTAM) of flight hazards
Acronym	NPT	Nuclear (Non-)Proliferation Treaty
Acronym	NRE	Non-Recurring Expense
Acronym	NRHO	Near-Rectilinear Halo Orbit
Acronym	NRO	(US) National Reconnaissance Office Near-Rectilinear Orbit, see NRHO
Acronym	NROL	Launch for the (US) National Reconnaissance Office
Acronym	NS	New Shepard suborbital launch vehicle, by Blue Origin Nova Scotia, Canada Neutron Star
Acronym	NSF	[NasaSpaceFlight forum](http://forum.nasaspaceflight.com) National Science Foundation
Acronym	NSSL	National Security Space Launch, formerly EELV
Acronym	NTO	diNitrogen TetrOxide, N2O4; part of NTO/MMH hypergolic mix
Acronym	NTP	Nuclear Thermal Propulsion Network Time Protocol Notice to Proceed
Acronym	NTR	Nuclear Thermal Rocket
Acronym	OATK	Orbital Sciences / Alliant Techsystems merger, launch provider
Acronym	OCISLY	Of Course I Still Love You, Atlantic landing ~~barge~~ ship
Acronym	OECD	Organisation for Economic Cooperation and Development
Acronym	OFT	Orbital Flight Test
Acronym	OG2	Orbcomm's Generation 2 17-satellite network (see OG2-2 for first successful F9 landing)
Acronym	OLIT	Orbital Launch Integration Tower
Acronym	OLM	Orbital Launch Mount
Acronym	OML	Outer Mold Line, outer profile of an aircraft/aeroshell
Acronym	OMS	Orbital Maneuvering System
Acronym	OOA	Orbit Once Around launch maneuver
Acronym	OPTEMPO	Operating/Operational Tempo
Acronym	ORSC	Oxidizer-Rich Staged Combustion
Acronym	OSM	Operations Safety Manager
Acronym	OTF	Orbital Tank Farm
Acronym	OTV	Orbital Test Vehicle
Acronym	OWL	[Overwhelmingly Large Telescope](https://en.wikipedia.org/wiki/Overwhelmingly_Large_Telescope) project, abandoned in favor of ELT
Acronym	PAF	Payload Attach Fitting
Acronym	PAO	Public Affairs Officer
Acronym	PAS	Payload Adapter System
Acronym	PAZ	Formerly [SEOSAR-PAZ](https://directory.eoportal.org/web/eoportal/satellite-missions/p/paz), an X-band SAR from Spain
Acronym	PCV	Port Canaveral
Acronym	PDR	Preliminary Design Review
Acronym	PDV	Powered Descent Vehicle for retro-propulsive landing
Acronym	PGO	Probability of Go
Acronym	PICA-X	Phenolic Impregnated-Carbon Ablative heatshield compound, as modified by SpaceX
Acronym	PLASSF	People's Liberation Army Strategic Support Force, China
Acronym	PLF	Payload Fairing
Acronym	PLSS	Personal Life Support System
Acronym	PMA	ISS Pressurized Mating Adapter
Acronym	PMD	Propellant Management Device
Acronym	PMF	Propellant Mass Fraction
Acronym	PNT	Positioning, Navigation and Timing
Acronym	PPE	Power and Propulsion Element
Acronym	PPF	SpaceX Payload Processing Facility, Cape Canaveral
Acronym	PSLV	Polar Satellite Launch Vehicle
Acronym	PSLV	[Polar Satellite Launch Vehicle](https://en.wikipedia.org/wiki/Polar_Satellite_Launch_Vehicle)
Acronym	PSLV-CA	Polar Satellite Launch Vehicle - Core Alone (without strap-on boosters)
Acronym	PSLV-G	Polar Satellite Launch Vehicle, with six 1 m diameter, 10 m long strap-on boosters
Acronym	PSLV-XL	Polar Satellite Launch Vehicle, with six 1 m diameter, 13.5 m long strap-on boosters
Acronym	PSOM	Solid Propellant Strap-On Motor, used in the PSLV
Acronym	PSP	Parker Solar Probe
Acronym	PTC	Passive Thermal Control
Acronym	PTK-NP	Roscosmos [Piloted Transport Ship, New Generation](https://en.wikipedia.org/wiki/Prospective_Piloted_Transport_System)
Acronym	QA	Quality Assurance/Assessment
Acronym	QAM	Quality Assurance Manager [Quadrature Amplitude Modulation](https://en.wikipedia.org/wiki/QAM)
Acronym	QD	Quick-Disconnect
Acronym	RAAN	[Right Ascension of the Ascending Node](https://en.wikipedia.org/wiki/Longitude_of_the_ascending_node)
Acronym	RAL	Rutherford Appleton Laboratory, UK
Acronym	RCC	Reinforced Carbon-Carbon
Acronym	RCO	Range Control Officer
Acronym	RCS	Reaction Control System
Acronym	RD-180	[RD-series Russian-built rocket engine](https://en.wikipedia.org/wiki/RD-180), used in the Atlas V first stage
Acronym	REL	Reaction Engines Limited, England
Acronym	RFIC	Radio Frequency Integrated Circuit
Acronym	RFNA	Red Fuming Nitric Acid, hypergolic oxidiser
Acronym	RFP	Request for Proposal
Acronym	RIO	[Radar Intercept Officer](https://en.wikipedia.org/wiki/Naval_flight_officer)
Acronym	RLV	Reusable Launch Vehicle
Acronym	RLV-TD	Reusable Launch Vehicle - Technology Demonstrator
Acronym	RNTLS	Return Near To Launch Site (ASDS in port)
Acronym	ROC	Range Operations Coordinator Radius of Curvature
Acronym	ROFI	Radial Outward-Firing Initiator
Acronym	Roomba	[Remotely-Operated Orientation and Mass Balance Adjuster](https://www.reddit.com/r/spacex/comments/6k8gzg//djk5g68/), used to hold down a stage on the ASDS
Acronym	ROSA	Roll-Out Solar Array (designed by Deployable Space Systems)
Acronym	Roscosmos	[State Corporation for Space Activities, Russia](https://en.wikipedia.org/wiki/Roscosmos_State_Corporation)
Acronym	RP-1	Rocket Propellant 1 (enhanced kerosene)
Acronym	RPA	["Rocket Propulsion Analysis"](http://www.propulsion-analysis.com/index.htm) computational tool
Acronym	RPY	Roll/Pitch/Yaw
Acronym	RRR	Reflight Readiness Review (see LRR)
Acronym	RS-25	Rocketdyne-developed rocket engine used for Shuttle; see SSME, SLS
Acronym	RSI	Reusable Surface Insulation (Shuttle's ceramic fiber tiles)
Acronym	RSS	[Rotating Service Structure](https://en.wikipedia.org/wiki/Kennedy_Space_Center_Launch_Complex_39#Launch_towers) at LC-39 Realscale Solar System, mod for KSP
Acronym	RTF	Return to Flight
Acronym	RTG	Radioisotope Thermoelectric Generator
Acronym	RTLS	Return to Launch Site
Acronym	RUAG	Rüstungs Unternehmen Aktiengesellschaft (Joint Stock Defense Company), Switzerland
Acronym	RUD	Rapid Unplanned Disassembly Rapid Unscheduled Disassembly Rapid Unintended Disassembly
Acronym	RUS	Raptor-powered Upper Stage, and/or ground equipment to support same
Acronym	s/c	Spacecraft
Acronym	SAA	[Space Act Agreement](https://en.wikipedia.org/wiki/Space_Act_Agreement), formal authorization of 'other transactions'
Acronym	SABRE	Synergistic Air-Breathing Rocket Engine, hybrid design by REL
Acronym	SAFER	[Simplified Aid For EVA Rescue](https://en.wikipedia.org/wiki/Simplified_Aid_For_EVA_Rescue)
Acronym	SAR	Synthetic Aperture Radar (increasing resolution with parallax)
Acronym	SAS	[Stability Augmentation System](http://wiki.kerbalspaceprogram.com/wiki/SAS), available when launching craft in KSP
Acronym	SBSP	Space-Based Solar Power generation
Acronym	SCADA	[Supervisory Control And Data Acquisition](https://en.wikipedia.org/wiki/SCADA) remote monitoring and control
Acronym	SDS	[Satellite Data System](https://en.wikipedia.org/wiki/Satellite_Data_System)
Acronym	SDSC	Satish Dhawan Space Centre
Acronym	SEB	Single-Event induced Burnout, radiation damage causing destructively high current
Acronym	SECO	Second-stage Engine Cut-Off
Acronym	SEE	Single-Event Effect of radiation impact
Acronym	SEGR	Single-Event Gate Rupture, transistor gate destroyed by radiation impact
Acronym	SEL	Single-Event Latchup, transistor stuck high due to radiation damage Sun-Earth Lagrange point
Acronym	SEP	Solar Electric Propulsion [Solar Energetic Particle](https://en.wikipedia.org/wiki/Solar_energetic_particle) Société Européenne de Propulsion
Acronym	SES	Formerly Société Européenne des Satellites, a major SpaceX customer Second-stage Engine Start
Acronym	SET	Single-Event Transient, spurious radiation discharge through a circuit
Acronym	SFNA	Stable Fuming Nitric Acid, hypergolic oxidizer
Acronym	SHAR	Sriharikota Range
Acronym	SHLLV	Super-Heavy Lift Launch Vehicle (over 50 tons to LEO)
Acronym	SHLV	Super-Heavy Lift Launch Vehicle (over 50 tons to LEO)
Acronym	SIP	Strain Isolation Pad for Shuttle's heatshield tiles
Acronym	SIRCA	Silicone Impregnated Reusable Ceramic Ablator
Acronym	SITVC	Secondary Injection Thrust Vector Control
Acronym	SLC-37	Space Launch Complex 37, Canaveral (ULA Delta IV)
Acronym	SLC-40	Space Launch Complex 40, Canaveral (SpaceX F9)
Acronym	SLC-41	Space Launch Complex 41, Canaveral (ULA Atlas V)
Acronym	SLC-4E	Space Launch Complex 4-East, Vandenberg (SpaceX F9)
Acronym	SLC-4W	Space Launch Complex 4-West, Vandenberg (SpaceX F9, landing)
Acronym	SLCH4	Slush/Supercooled Liquid Methane
Acronym	SLP	Second Launch Pad at Satish Dhawan Space Centre, operational since 2005
Acronym	SLS	Space Launch System heavy-lift
Acronym	SMAB	(Former) Solid Motor Assembly Building, Cape Canaveral
Acronym	SMART	"Sensible Modular Autonomous Return Technology", ULA's engine reuse philosophy
Acronym	SMAW	[Shielded Metal Arc Welding](https://en.wikipedia.org/wiki/Shielded_metal_arc_welding)
Acronym	SMD	Science Mission Directorate, NASA
Acronym	SN	(Raptor/Starship) Serial Number
Acronym	SNC	Sierra Nevada Corporation
Acronym	SoI	Saturnian Orbital Insertion maneuver Sphere of Influence
Acronym	SOMD	Space Operations Mission Directorate, NASA
Acronym	SOP	Standard Operating Procedure
Acronym	SOX	Solid Oxygen, generally not desirable Sarbanes-Oxley US accounting regulations
Acronym	SPAM	*SpaceX Proprietary Ablative Material* (backronym)
Acronym	SPICE	SPectral Imaging of the Coronal Environment, instrument on ESA's Solar Orbiter
Acronym	SPIF	Spacecraft Processing and Integration Facility, Cape Canaveral (now PPF)
Acronym	SPMT	Self-Propelled Mobile Transporter
Acronym	SPoF	Single Point of Failure
Acronym	SRB	Solid Rocket Booster
Acronym	SRP	Supersonic Retro-Propulsion
Acronym	SSAU	State Space Agency of Ukraine
Acronym	SSBA	Space Situational Based Awareness
Acronym	SSC	Stennis Space Center, Mississippi
Acronym	SSH	Starship + SuperHeavy (see BFR)
Acronym	SSL	Space Systems/Loral, satellite builder
Acronym	SSME	[Space Shuttle Main Engine](https://en.wikipedia.org/wiki/Space_Shuttle_main_engine)
Acronym	SSO	Sun-Synchronous Orbit
Acronym	SSP	Space-based Solar Power
Acronym	SSRMS	Space Station Remote Manipulator System (*Canadarm*)
Acronym	SSTO	Single Stage to Orbit Supersynchronous Transfer Orbit
Acronym	SSVP	Sistema Stykovki i Vnutrennego Perekhoda, Russian docking standard
Acronym	STA	Special Temporary Authorization (issued by FCC for up to 6 months) Structural Test Article
Acronym	STEREO	Solar TErrestrial RElations Observatory, GSFC
Acronym	STLS	South Texas Launch Site, Boca Chica
Acronym	STP	[Standard Temperature and Pressure](https://en.wikipedia.org/wiki/Standard_conditions_for_temperature_and_pressure) [Space Test Program](https://en.wikipedia.org/wiki/Space_Test_Program), see STP-2
Acronym	STP-2	[Space Test Program 2](https://en.wikipedia.org/wiki/Space_Test_Program#Upcoming_Activities), DoD programme, second round
Acronym	STS	Space Transportation System (*Shuttle*)
Acronym	SUFR	Straighten Up and Fly Right, weight jettison event during Curiosity EDL
Acronym	SV	Space Vehicle
Acronym	T/E	Transporter/Erector launch pad support equipment
Acronym	TAL	[Transoceanic Abort Landing](https://en.wikipedia.org/wiki/Space_Shuttle_abort_modes#Transoceanic_abort_landing)
Acronym	TAN	[Thrust Augmented Nozzle](http://selenianboondocks.com/2007/11/thrust-augmented-nozzles/)
Acronym	TCM	Trajectory Correction Maneuver
Acronym	TDRSS	(US) Tracking and Data Relay Satellite System
Acronym	TE	Transporter/Erector launch pad support equipment
Acronym	TEA-TEB	[Triethylaluminium](https://en.wikipedia.org/wiki/Triethylaluminium)-[Triethylborane](https://en.wikipedia.org/wiki/Triethylborane), igniter for Merlin engines; spontaneously burns, green flame
Acronym	TEI	Trans-Earth Injection maneuver
Acronym	TEL	Transporter/Erector/Launcher, ground support equipment (see TE)
Acronym	TFR	Temporary Flight Restriction
Acronym	TID	Total Ionizing Dose of radiation
Acronym	TIG	[Gas Tungsten Arc Welding](https://en.wikipedia.org/wiki/Gas_tungsten_arc_welding) (or Tungsten Inert Gas)
Acronym	TLA	Three Letter Acronym
Acronym	TLE	Two-Line Element dataset issued by NORAD
Acronym	TLI	Trans-Lunar Injection maneuver
Acronym	TLP	Third Launch Pad at Satish Dhawan Space Centre (Proposed)
Acronym	TMI	Trans-Mars Injection maneuver
Acronym	TMT	Thirty-Meter Telescope, Hawaii
Acronym	TOSC	Test and Operations Support Contract
Acronym	TPA	TurboPump Assembly, feeds fuel to a rocket engine
Acronym	TPS	Thermal Protection System for a spacecraft (on the Falcon 9 first stage, the engine "Dance floor")
Acronym	TRL	Technology Readiness Level
Acronym	TS	Thrust Simulator
Acronym	TSFC	Thrust Specific Fuel Consumption (fuel used per unit thrust)
Acronym	TSM	Tail Service Mast, holding lines/cables for servicing a rocket first stage on the pad
Acronym	TSTO	Two Stage To Orbit rocket
Acronym	TT&C;	Telemetry, Tracking and Control communications with a satellite
Acronym	TVC	Thrust Vector Control
Acronym	TWR	Thrust-to-Weight Ratio
Acronym	UDMH	Unsymmetrical dimethylhydrazine, liquid hypergolic propellant
Acronym	UDMH	[Unsymmetrical DiMethylHydrazine](https://en.wikipedia.org/wiki/Unsymmetrical_dimethylhydrazine), used in hypergolic fuel mixes
Acronym	UHF	Ultra-High Frequency radio
Acronym	ULA	United Launch Alliance (Lockheed/Boeing joint venture)
Acronym	USAF	United States Air Force
Acronym	USOS	United States Orbital Segment
Acronym	USSF	United States Space Force
Acronym	VAB	Vehicle Assembly Building
Acronym	VAFB	Vandenberg Air Force Base, California
Acronym	VBB	Very Big Brother (Blue Origin's proposed VTVL vehicle, unknown payload to LEO)
Acronym	VEEGA	Venus/Earth/Earth Gravity Assist
Acronym	VFR	[Visual Flight Rules](https://en.wikipedia.org/wiki/Visual_flight_rules)
Acronym	VG	Virgin Galactic
Acronym	VIF	Vertical Integration Facility
Acronym	VLBI	Very-Long-Baseline Interferometry
Acronym	VLEO	V-band constellation in LEO Very Low Earth Orbit
Acronym	VLT	Very Large Telescope, Chile
Acronym	VSAT	Very Small Aperture Terminal antenna (minimally-sized antenna, wide beam width, high power requirement)
Acronym	VSSC	Vikram Sarabhai Space Centre
Acronym	VTHL	Vertical Takeoff, Horizontal Landing (*Shuttle*)
Acronym	VTOL	Vertical Take-Off and Landing
Acronym	VTS	Vertical Test Stand
Acronym	VTVL	Vertical Takeoff, Vertical Landing
Acronym	VV	Visiting Vehicle (visitor to the Station)
Acronym	WDR	Wet Dress Rehearsal (with fuel onboard)
Acronym	WFIRST	Wide-Field Infra-Red Survey Telescope
Acronym	WFNA	White Fuming Nitric Acid, hypergolic oxidiser
Acronym	WISP	Wireless Internet Service Provider
Acronym	WSMR	White Sands Missile Range, New Mexico
Acronym	WSO	[Weapons Systems Officer](https://en.wikipedia.org/wiki/Weapon_systems_officer)
Acronym	XIPS-25	[25cm Xenon Ion Propulsion System](https://en.wikipedia.org/wiki/XIPS-25) used on Boeing 702 satellites
Acronym	XIRCA	SpaceX SIRCA TPS, as [placed in context](/r/spacex/comments/7p6763/_/dsfw57y/) by brickmack
Acronym	ZBP	Zero Pre-Breathe (spacesuit and habitat at same pressure
Acronym	ZPS	Zero Prebreathe Spacesuit
Jargon	ablative	Material which is intentionally destroyed in use (for example, heatshields which burn away to dissipate heat)
Jargon	apoapsis	Highest point in an elliptical orbit (when the orbiter is slowest)
Jargon	apogee	Highest point in an elliptical orbit around Earth (when the orbiter is slowest)
Jargon	apohelion	Highest point in an elliptical orbit around the Sun (when the orbiter is slowest)
Jargon	autogenous	(Of a propellant tank) Pressurising the tank using boil-off of the contents, instead of a separate gas like helium
Jargon	bipropellant	Rocket propellant that requires oxidizer (eg. RP-1 and liquid oxygen)
Jargon	blisk	Portmanteau: [Bladed disk](https://en.wikipedia.org/wiki/Blisk)
Jargon	cislunar	Between the Earth and Moon; within the Moon's orbit
Jargon	crossfeed	Using the propellant tank of a side booster to fuel the main stage, or vice versa
Jargon	cryogenic	Very low temperature fluid; materials that would be gaseous at room temperature/pressure (In re: rocket fuel) Often synonymous with hydrolox
Jargon	dancefloor	Attachment structure for the Falcon 9 first stage engines, below the tanks
Jargon	deep throttling	Operating an engine at much lower thrust than normal
Jargon	electrolysis	Application of DC current to separate a solution into its constituents (for example, water to hydrogen and oxygen)
Jargon	EMdrive	Prototype-stage reactionless propulsion drive, using an asymmetrical resonant chamber and microwaves
Jargon	engine-rich	Fuel mixture that includes engine parts on fire
Jargon	granularity	(In re: rocket engines) Allowing for engine-out capability when determining minimum engine count
Jargon	high beta	Times of year when the Earth-Sun line and the plane of orbit are nearly perpendicular
Jargon	hopper	Test article for ground and low-altitude work (eg. Grasshopper)
Jargon	hydrolox	Portmanteau: liquid hydrogen fuel, liquid oxygen oxidizer
Jargon	hypergolic	A set of two substances that ignite when in contact
Jargon	iron waffle	Compact "waffle-iron" aerodynamic control surface, acts as a wing without needing to be as large; also, "grid fin"
Jargon	kerolox	Portmanteau: kerosene fuel, liquid oxygen oxidizer
Jargon	lithobraking	"Braking" by hitting the [ground](https://en.wiktionary.org/wiki/lith-)
Jargon	methalox	Portmanteau: methane fuel, liquid oxygen oxidizer
Jargon	milspec	Military Specification
Jargon	monopropellant	Rocket propellant that requires no oxidizer (eg. hydrazine)
Jargon	periapsis	Lowest point in an elliptical orbit (when the orbiter is fastest)
Jargon	perigee	Lowest point in an elliptical orbit around the Earth (when the orbiter is fastest)
Jargon	perihelion	Lowest point in an elliptical orbit around the Sun (when the orbiter is fastest)
Jargon	powerpack	Pre-combustion power/flow generation assembly (turbopump etc.) Tesla's Li-ion battery rack, for electricity storage at scale
Jargon	prepreg	[Pre-impregnated composite fibers](https://en.wikipedia.org/wiki/Pre-preg) where the matrix/binding resin is applied before wrapping, instead of injected later
Jargon	pyrophoric	A substance which ignites spontaneously on contact with air
Jargon	quess	Portmanteau: Qualified Guess (common parlance: "estimate")
Jargon	rainbirds	Water deluge system at the launch tower base, activated just before ignition
Jargon	Raptor	[Methane-fueled rocket engine](https://en.wikipedia.org/wiki/Raptor_\(rocket_engine_family\)) under development by SpaceX
Jargon	regenerative	A method for cooling a rocket engine, by [passing the cryogenic fuel through channels in the bell or chamber wall](https://en.wikipedia.org/wiki/Regenerative_cooling_\(rocket\))
Jargon	retropropulsion	Thrust in the opposite direction to current motion, reducing speed
Jargon	Sabatier	Reaction between hydrogen and carbon dioxide at high temperature and pressure, with nickel as catalyst, yielding methane and water
Jargon	scrub	Launch postponement for any reason (commonly GSE issues)
Jargon	Starliner	Boeing commercial crew capsule [CST-100](https://en.wikipedia.org/wiki/Boeing_CST-100_Starliner)
Jargon	Starlink	SpaceX's world-wide satellite broadband constellation
Jargon	tanking	Filling the tanks of a rocket stage
Jargon	tripropellant	Rocket propellant in three parts (eg. lithium/hydrogen/fluorine)
Jargon	turbopump	High-pressure turbine-driven propellant pump connected to a rocket combustion chamber; raises chamber pressure, and thrust
Jargon	ullage motor	Small rocket motor that fires to push propellant to the bottom of the tank, when in zero-g
Event	Amos-6	2016-09-01|F9-029 Full Thrust, core B1028, ~~GTO comsat~~ Pre-launch test failure
Event	AsiaSat-6	2014-09-07|F9-013 v1.1, GTO comsat
Event	AsiaSat-8	2014-08-05|F9-011 v1.1, GTO comsat
Event	CASSIOPE	2013-09-29|F9-006 v1.1, [Cascade, Smallsat and Ionospheric Polar Explorer](https://en.wikipedia.org/wiki/CASSIOPE); engine starvation during landing attempt
Event	COTS-1	2010-12-08|F9-002, COTS demonstration
Event	COTS-2	2012-05-22|F9-003, COTS berthing demonstration
Event	CRS-1	2012-10-08|F9-004, first CRS mission; secondary payload sacrificed
Event	CRS-10	2017-02-19|F9-032 Full Thrust, core B1031, Dragon cargo; first daytime RTLS
Event	CRS-2	2013-03-01|F9-005, Dragon cargo; final flight of Falcon 9 v1.0
Event	CRS-3	2014-04-18|F9-009 v1.1, Dragon cargo; soft ocean landing, first core with legs
Event	CRS-4	2014-09-21|F9-012 v1.1, Dragon cargo; soft ocean landing
Event	CRS-5	2015-01-10|F9-014 v1.1, Dragon cargo; first ASDS landing attempt, maneuvering failure
Event	CRS-6	2015-04-14|F9-018 v1.1, Dragon cargo; second ASDS landing attempt, overcompensated angle of entry
Event	CRS-7	2015-06-28|F9-020 v1.1, ~~Dragon cargo~~ Launch failure due to second-stage outgassing
Event	CRS-8	2016-04-08|F9-023 Full Thrust, core B1021, Dragon cargo; first ASDS landing
Event	CRS-9	2016-07-18|F9-027 Full Thrust, core B1025, Dragon cargo; RTLS landing
Event	DM-1	2019-03-02|SpaceX CCtCap Demo Mission 1
Event	DM-2	2020-05-30|SpaceX CCtCap Demo Mission 2
Event	DSCOVR	2015-02-11|F9-015 v1.1, [Deep Space Climate Observatory](https://en.wikipedia.org/wiki/Deep_Space_Climate_Observatory) to L1; soft ocean landing
Event	DSQU	2010-06-04|Maiden Falcon 9 (F9-001, B0003), Dragon Spacecraft Qualification Unit
Event	Echostar-23	2017-03-16|F9-031 Full Thrust, core B1030, GTO comsat; stage expended
Event	Eutelsat-115WB	2015-03-02|F9-016 v1.1, dual GTO comsat
Event	Eutelsat-117WB	2016-06-15|F9-026 Full Thrust, core B1024, dual GTO comsat; ASDS landing failure due to early burn
Event	F1F1	2006-03-24|Falcon 1 first launch attempt; failure
Event	F1F2	2007-03-21|Falcon 1 second flight attempt; failure
Event	F1F3	2008-08-03|Falcon 1 third flight attempt; failure
Event	F1F4	2008-09-28|Falcon 1 fourth flight attempt, first success
Event	F1F5	2009-07-14|Falcon 1 fifth launch attempt, RazakSat to LEO
Event	Inmarsat-5 F4	2017-05-16|F9-034 Full Thrust, core B1034, GTO comsat; expended
Event	Iridium-1	2017-01-14|F9-030 Full Thrust, core B1029, 10x Iridium-NEXT to LEO; first landing on JRTI
Event	Jason-3	2016-01-17|F9-019 v1.1, [Jason-3](https://en.wikipedia.org/wiki/Jason-3); leg failure after ASDS landing
Event	JCSAT-14	2016-05-06|F9-024 Full Thrust, core B1022, GTO comsat; first ASDS landing from GTO
Event	JCSAT-16	2016-08-14|F9-028 Full Thrust, core B1026, GTO comsat; ASDS landing
Event	NROL-76	2017-05-01|F9-033 Full Thrust, core B1032, ^(classified payload); landed at LZ-1
Event	OA-4	2015-12-06|ULA Atlas V, OATK Cygnus cargo
Event	OA-5	2016-10-17|OATK Antares 230, Cygnus cargo
Event	OA-6	2016-03-23|ULA Atlas V, OATK Cygnus cargo
Event	OG2-1	2014-07-14|F9-010 v1.1, six OG2 satellites to LEO; soft ocean landing
Event	OG2-2	2015-12-22|F9-021 Full Thrust, core B1019, 11 OG2 satellites to LEO; first RTLS landing
Event	Orb-1	2014-01-09|Orbital Antares 120, first Cygnus cargo
Event	Orb-2	2014-07-13|Orbital Antares 120, Cygnus cargo
Event	Orb-3	2014-10-28|Orbital Antares 130, ~~Cygnus cargo~~ Thrust loss at launch
Event	Orb-D1	2013-09-18|Orbital Antares 110, Cygnus cargo; COTS demo
Event	SES-8	2013-12-03|F9-007 v1.1, first SpaceX launch to GTO
Event	SES-9	2016-03-04|F9-022 Full Thrust, core B1020, GTO comsat; ASDS lithobraking
Event	TGO	2016-03-14|(Launch of) Trace Gas Orbiter at Mars, an ESA mission
Event	Thaicom-6	2014-01-06|F9-008 v1.1 to GTO, re-entry burn attempted
Event	Thaicom-8	2016-05-27|F9-025 Full Thrust, core B1023, GTO comsat; ASDS landing
Event	TurkmenAlem52E	2015-04-27|F9-017 v1.1, GTO comsat