| 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 | 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 under construction |
| 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 | 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 | 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 | DLRR | Delta Launch Readiness Review |
| 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 | EAR | Export Administration Regulations, covering technologies that are not solely military |
| Acronym | EBAM | [Electron Beam Additive Manufacture](https://en.wikipedia.org/wiki/Electron_beam_additive_manufacturing) |
| Acronym | EBM | [Electron Beam Melting](https://en.wikipedia.org/wiki/Electron_beam_additive_manufacturing) additive manufacture |
| 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 | 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 medium-lift vehicle) |
| Acronym | F9E | Falcon 9 expendable |
| 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 | 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 | FHR | Falcon Heavy reusable |
| 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 | FONSI | [Findings of No Significant Environmental Impact](http://energy.gov/nepa/findings-no-significant-impact-fonsi) |
| 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 | FRR | Flight Readiness Review |
| 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 | 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 | Geosynchronous Satellite Launch Vehicle |
| Acronym | GSLV | (India's) Geostationary Launch Vehicle |
| Acronym | GSO | Geosynchronous Orbit (any Earth orbit with a 24-hour period) Guang Sheng Optical telescopes |
| 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 (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 | 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 | I*_sp_* | Specific impulse (as discussed by [Scott Manley](https://www.youtube.com/watch?v=nnisTeYLLgs), and detailed by [David Mee](https://www.youtube.com/watch?v=lo-gg6e6ctw) on YouTube) |
| 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) |
| 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 | IVF | [Integrated Vehicle Fluids ^PDF](http://www.ulalaunch.com/uploads/docs/Published_Papers/Supporting_Technologies/Space_Access_Society_2012.pdf) |
| 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, Pasadena, 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 mod |
| 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 | Paywalled section of the NasaSpaceFlight forum [Lagrange Point](https://en.wikipedia.org/wiki/Lagrangian_point) 2 of a two-body system, beyond the smaller body ([Sixty Symbols](https://www.youtube.com/watch?v=mxpVbU5FH0s) video explanation) |
| 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 | 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 |
| 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 | M1a | Merlin 1 kerolox rocket engine, original (2006), 340kN |
| Acronym | M1b | Merlin 1 kerolox rocket engine, revision B (unflown), 360kN |
| Acronym | M1c | Merlin 1 kerolox rocket engine, revision C (2008), 556-660kN |
| Acronym | M1d | Merlin 1 kerolox rocket engine, revision D (2013), 620-690kN, uprated to 730 then 845kN |
| Acronym | M1dVac | Merlin 1 kerolox rocket engine, revision D (2013), vacuum optimized, 934kN |
| 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 | 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 | NDE | Non-Destructive Examination |
| Acronym | NdGT | Neil deGrasse Tyson |
| Acronym | NDS | [NASA Docking System](https://en.wikipedia.org/wiki/NASA_Docking_System), implementation of the international standard |
| Acronym | NDT | Non-Destructive Testing |
| Acronym | NEO | Near-Earth Object |
| 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 | 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 Airmen](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 | NSS | National Security Space |
| 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 |
| 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 | 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 | 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 | 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 | 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 | PUG | [Payload User Guide (PDF)](http://www.spacex.com/sites/spacex/files/falcon_9_users_guide_rev_2.0.pdf) |
| 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 | RSD | Rapid Scheduled Disassembly (explosive bolts/charges) |
| 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 | SD | SuperDraco hypergolic abort/landing engines |
| 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, comsat operator Second-stage Engine Start |
| Acronym | SET | Single-Event Transient, spurious radiation discharge through a circuit |
| Acronym | SF | Static fire |
| 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 | SLM | [Selective Laser Melting](https://en.wikipedia.org/wiki/Selective_laser_melting) additive manufacture |
| 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 | SSF | Sneaky Static Fire |
| 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 | 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 | 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 | VIF | Vertical Integration Facility |
| Acronym | VLBI | Very-Long-Baseline Interferometry |
| Acronym | VLEO | V-band constellation in LEO Very Low Earth Orbit |
| 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 | 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 |