| SSPFA | Space Shuttle Program Flight Assignment | In English | |
| SSPGSE | Space Shuttle Program Ground Support Equipment | In English | |
| SSPII | Space Shuttle Program Implementing Instruction | In English | |
| SSPM | Space Shuttle Program Manager | In English | → Management |
| SSPO | Space Station Projects Office | In English | |
| SSPO | Space Shuttle Program Office | In English | |
| SSPP | Space Station Program Participant | In English | |
| SSPPSG | Space Shuttle PAyload Planning Steering Group | In English | → Management |
| SSPRO | Space Shuttle Program Resident Office | In English | |
| SSPS | Solar Satellite Power Station | In English | → Energy economics |
| SSPS | Space Shuttle Program Schedule | In English | |
| SSRIMp | Space Station Resource Impact Model | In English | |
| SSRMS | Space Station Remote Manipulator System | In English | |
| SSROP | Space Station Resource Optimization Program | In English | |
| SSS | Spacecraft Software System | In English | → Software |
| SSS | Space Shuttle Segment | In English | |
| SSS | Spinning Sun Sensor | In English | → Astronomy |
| SSSC | Space Station Support Center | In English | |
| SSSS | Space Shuttle System Specification | In English | |
| SSSSR | Space Shuttle System Safety Review | In English | |
| SSST | Space Station System Trainer | In English | |
| SST | Shuttle System Test | In English | |
| SST | Space Surveillance and Tracking | In English | → Astronomy |
| SST | Spacecraft Systems Test | In English | |
| SSTC | Space Shuttle Test Conductor | In English | |
| SSTCLS | Space Shuttle Test, Checkout, and Launch Support | In English | |
| SSTF | Space Station Training Facility | In English | |
| SSTO | Single Stage To Orbit | In English | |
| SSTS | Satellite Surveillance and Tracking System | In English | |
| SSTS | Space Surveillance and Tracking System | In English | |
| SSTS | Space-Based Surveillance and Tracking System | In English | |
| SSUS | Spinning Solid Upper Stage | In English | |
| SSUSA | SSUS for Atlas-centaur-class spacecraft | In English | |
| SSUSD | SSUS for Delta-class spacecraft | In English | |
| SSUSP | Spinning Solid Upper Stage Project | In English | |
| SSV | Space Shuttle Vehicle | In English | |
| SSV | Space Sortie Vehicle | In English | |
| SSWG | Shuttle Security Working Group | In English | |
| SSWP | Space Station Work Package | In English | |
| ST | Star Tracker | In English | → Astronomy |
| ST | Space Telescope | In English | → Astronomy |
| ST | Spacelab Technology | In English | |
| STA | Shuttle Training Aircraft | In English | |
| STACC | Standard Telemetry And Communications Component | In English | → Astronomy → Telecommunications |
| STADAN | Satellite Tracking And Data Acquisition Network | In English | → Data |
| STADAN | Space Tracking And Data Acquisition Network | In English | → Data |
| STAG | Shuttle Turnaround Analysis Group | In English | |
| STAR | Space Transportation Automated Reconfiguration | In English | |
| STAR | Shuttle Turnaround Analysis Report | In English | |
| STARS | Space Transportation Automated Reconfiguration System | In English | |
| STAS | Space Transportation Architecture Study | In English | |
| STATS | Star Tracker Alignment Test Set | In English | → Astronomy |
| STBE | Space Transportation Booster Engine | In English | |
| STC | Satellite TRacking Center | In English | |
| STC | Shuttle Test Conductor | In English | |
| STC | Spacecraft Test Conductor | In English | |
| STC | Satellite Test Center | In English | |
| STC | Space Technology Center | In English | |
| STD | Spacecraft Technology Division | In English | |
| STD | Shuttle Test Detector | In English | |
| STDN | Spacecraft Tracking and Data Network | In English | → Data → Networks, communication |
| STEP | Space Test Experiments Platform | In English | |
| STF | Satellite Test Facility | In English | |
| STG | Space Task Group | In English | |
| STG | Shuttle Test Group | In English | |
| STIC | Space Test Integration Contract | In English | |
| STICA | Space Technology Industrial and Commercial Applications | In English | → Serial publications, periodicals → Astronomy |
| STL | Space Technology Laboratories | In English | → Research institutes |
| STME | Space Transportation Main Engine | In English | |
| STOL | Short Takeoff and Landing | In English | → Aeronautics, aircraft |
| STP | Space Test Program | In English | |
| STP | Shuttle Technology Panel | In English | |
| STP | Space Technology Payload | In English | |
| STS | Shuttle Test Station | In English | |
| STS | Space Transportation System | In English | |
| STSAM | Space Transportation System Analysis Model | In English | |
| STSOC | Space Transportation System Operations Contract | In English | |
| STSOPO | Space Transportation System Operations Program Office | In English | |
| STSYM | Space Transportation System Model | In English | |
| SUMC | Space Ultrareliable Modular Computer | In English | → Hardware |
| SUMS | Shuttle Upper Atmosphere Mass Spectrometer | In English | → Astronomy → Analytical chemistry |
| SURE | Shuttle Users' Review and Evaluation | In English | |
| SURTEX | Shuttle-Released Technology Experiment | In English | |
| SURTEX | Shuttle-Released Target Experiment | In English | |
| SV | Shuttle Vehicle | In English | |
| SV | Space Vehicle | In English | |
| SVA&C | Shuttle Vehicle Assembly and Checkout | In English | |
| SVAB | Shuttle Vehicle Assembly Building | In English | |
| SVAC | Shuttle Vehicle Assembly and Checkout | In English | |
| SVB | Space Vehicle Booster | In English | |
| SVB | Shuttle Vehicle Booster | In English | |
| SVC | Spacecraft Vehicle Contractor | In English | |
| SVCDS | Space Vehicle Computer Design System | In English | → Hardware |
| SVCDS | Space Vehicle Control/Display Simulation | In English | → Human-computer interaction |
| SVCMU | Space Vehicle Control and Monitor Unit | In English | → 0054 |
| SVDS | Space Vehicle Dynamics Simulation | In English | |
| SVDT | Space Vehicle Development Team | In English | |
| SVE | Space Vehicle Equipment | In English | |
| SVIU | Space Vehicle Interface Unit | In English | |
| SVO | Space Vehicle Operations | In English | |
| SVOD | Space Vehicle Operations Director | In English | |
| SVR | Space Vehicle Requirement | In English | |
| SVS | Shuttle Vehicle Simulator | In English | |
| SVS | Space Vehicle System | In English | |
| SVT | Space Vehicle Test | In English | |
| SW | Solar Wing | In English | |
| SWPA | Shuttle Wing Panel Analysis | In English | |
| TAB | Time After Burst | In English | |
| TAL | Transatlantic Abort Landing | In English | → Aeronautics, aircraft |
| TAL | Trans-Atlantic Abort Landing | In English | |
| TALAR | Tactical Approach and Landing Radar | In English | → Aeronautics, aircraft |
| TALO | Time After Lift-Off | In English | |
| TBC | The Boeing Company | In English | |
| TDRS | Tracking and Data Relay Satellite | In English | |
| TDRSS | Tracking and Data Relay Satellite System | In English | |
| TDS | Technology Demonstration Satellite | In English | |
| TET | Trajectory Events Time Line | In English | |
| TETRA | Terminal Tracking Telescope | In English | |
| TFCS | Triplex Flight Control Subsystem | In English | |
| TFI | Technology Flight Instrumentation | In English | → Aeronautics, aircraft |
| TFI | Time From Ignition | In English | |
| TFL | Time From Launch | In English | |
| TFS | Telemetry Format Selection | In English | |
| TGS | Telemetry Ground System | In English | |
| TGS | Telemetry Ground Station | In English | |
| TGSE | Telemetry Ground Support Equipment | In English | |
| THEMIS | Time History of Events and Macroscale Interactions during Sunstorms | In English | → Astronomy |
| TIFDL | TOPEX Interfacility Data Link | In English | |
| TIFS | Total In-Flight Simulator | In English | → Aeronautics, aircraft |
| TIG | Time of/until Ignition | In English | |
| TIO | Target Insertion Orbit | In English | |
| TIPS | Thruster Instability Protection System | In English | |
| TIR | Terminal Imaging Radar | In English | → Geodesy, cartography |
| TIROS | Television Infrared Observation Satellite | In English | → Telecommunications |
| TKSC | Tsukuba Space Center | In English | → Astronomy |
| TLI | Translunar Injection | In English | |
| TLV | Target Launch Vehicle | In English | |
| TMECO | Time of Main Engine Cutoff | In English | |
| TMG | Thermal Meteoroid Garment | In English | |
| TMI | Transmars Injection | In English | |
| TMR | TOPEX Microwave Radiometer | In English | |
| TO | Takeoff | In English | → Aeronautics, aircraft |
| TOI | Transfer Orbit Insertion | In English | |
| TOPS | Transfer Orbit Perigee Stage | In English | |
| TOS | Transfer Orbit Stage | In English | |
| TOW | Tank and Orbiter Weight | In English | |
| TP | Time to Perigee | In English | |
| TPL | Transpacific Landing | In English | |
| TR | Time to Retrofire | In English | |
| TR/SBS | TeleOperator Retrieval/Skylab Boost System | In English | |
| TRDDS | Teal Ruby Data Documentation System | In English | |
| TRDF | Teal Ruby Data Formatter | In English | |
| TRE | Teal Ruby Experiment | In English | |
| TRE/ITU | Teal Ruby Experiment/Infrared Telescope Unit | In English | → Astronomy |
| TRS | Teal Ruby Spacecraft | In English | |
| TSP | Trajectory Shaping Program | In English | → Software |
| TSP | Trajectory Synthesis Program | In English | → Software |
| TsPK | Tsentr Podgotovka Kosmonavti | In Russian | |
| TSS | Tethered Satellite System | In English | |
| TT&C | Tracking, Telemetry, and Command | In English | |
| TT&C | Tracking, Telemetry, and Control | In English | |
| TT&C | Telemetry, Tracking, and Communications | In English | → Telecommunications |
| TTA | Time To Apogee | In English | → Astronomy |
| TTC | Telemetry, Telecommand and Control | In English | |
| TTCV | Tracking, Telemetry, Command, and Voice | In English | → Telecommunications |
| TTP | Time To Perigee | In English | → Astronomy |
| U3P | Union pour la Promotion de la Propulsion Photonique | In French | |
| UARS | Upper Atmosphere Research Satellite | In English | → Meteorology, climatology |
| UFO | Unknown Flying Object = OVNI | Objet Volant Non Identifié | In French = OVNI | Objecte Volador No Identificat | In Catalan = НЛО | Неидентифициран летящ обект | In Bulgarian = OVNI | Objeto Volador No Identificado | In Spanish = UFO | Unidentifiziertes Flugobjekt | In German = UFO | Unidentified Flying Object | In English = UFO | Uidentificeret flyvende objekt | In Danish = NIFO | Neidentigita Fluganta Objekto | In Esperanto = UFO | Unbekend fleanend objekt | In Frisian = עב"מ | עצם בלתי מזוהה | In Hebrew = OVNI | Oggetto Volante Non Identificato | In Italian = NLO | Neidentificēts lidojošs objekts | In Latvian = UFO | Uidentifisert flygende objekt | In Norwegian = UFO | Uidentifisert flygande objekt | In Nynorsk = NOL | Niezidentyfikowany Obiekt Latający | In Polish = OVNI | Objeto Voador Não Identificado | In Portuguese = OZN | Obiect Zburător Neidentificat | In Romanian = НЛО | Неопознанный летающий объект | In Russian = NLO | Neidentifikovani leteći objekat | In Serbo-Croatian |
In English | |
| UFO | Unbekend fleanend objekt = OVNI, НЛО, NIFO, עב"מ, NLO, NOL, OZN (look above) |
In Frisian | |
| UFO | Uidentifisert flygande objekt = OVNI, НЛО, NIFO, עב"מ, NLO, NOL, OZN (look above) |
In Nynorsk | |
| UFO | Uidentifisert flygende objekt = OVNI, НЛО, NIFO, עב"מ, NLO, NOL, OZN (look above) |
In Norwegian | |
| UFO | Unidentifiziertes Flugobjekt = OVNI, НЛО, NIFO, עב"מ, NLO, NOL, OZN (look above) |
In German | |
| UFO | Unidentified Flying Object = OVNI, НЛО, NIFO, עב"מ, NLO, NOL, OZN (look above) |
In English | |
| UFO | Uidentificeret flyvende objekt = OVNI, НЛО, NIFO, עב"מ, NLO, NOL, OZN (look above) |
In Danish | |
| ULO | Unmanned Launch Operations | In English | |
| ULV | Unmanned Launch Vehicle | In English | |
| UMO | Unmanned Orbital | In English | |
| UMVF | Unmanned Vertical Flight | In English | → Aeronautics, aircraft |
| UNOOSA | United Nations Office for Outer Space Affairs | In English | → United Nations → Astronomy |
| UoSAT | University of Surrey Satellite | In English | → Higher education, universities |
| UPS | Upright Perigee Stage | In English | |
| USA | United Space Alliance (www.unitedspacealliance.com) | In English | |
| USBI | United Space Booster, Incorporated | In English | |
| USS | Unmanned Space Satellite | In English | |
| UTS | Unmanned Teleoperator Spacecraft | In English | |
| UVF | Unmanned Vertical Flight | In English | → Aeronautics, aircraft |
| VFI | Verification Flight Instrumentation | In English | → Aeronautics, aircraft |
| VFR | Visual Flight Rule | In English | → Aeronautics, aircraft |
| VFT | Verification Flight Test | In English | → Aeronautics, aircraft |
| VFT | Vertical Flight Test | In English | → Aeronautics, aircraft |
| VGRF | Variable-Gravity Research Facility | In English | → Research institutes → Astronomy |
| VHAA | Very High Altitude Abort | In English | → Aeronautics, aircraft |
| VISTAR | Visible Space Tracking and Reconnaissance | In English | → Astronomy |
| VLF | Vertical Launch Facility | In English | → Aeronautics, aircraft |
| VLPS | Vandenberg Launch Processing System | In English | |
| VLS | Vertical Launch System | In English | → Aeronautics, aircraft |
| VLS | Vandenberg Launch Site | In English | |
| VLS | Vandenberg Launch and Landing Site | In English | |
| VLSST | Vandenberg Launch Site Support Team | In English |