| S | Spiral (for Galaxies) | - | Atmospheric Research Center |
| S/C | SpaceCraft | - | Atmospheric Research Center |
| SAA | South Atlantic Anomaly / Single Access Antenna | - | Atmospheric Research Center |
| SAGA | Solar Array Gain Augmentation | - | Atmospheric Research Center |
| SAIL | Shuttle Avionics Integration Laboratory | - | Atmospheric Research Center |
| SAM | Shuttle Activation Monitor | - | Atmospheric Research Center |
| SAMPEX | Solar Anomalous And Magnetospheric Particle EXplorer | - | Atmospheric Research Center |
| SAMS | Space Acceleration Measurement System | - | Atmospheric Research Center |
| SAO | Smithsonian Astrophysical Observatory | - | Atmospheric Research Center |
| SAR | Search And Rescue / Synthetic Aperture Radar | - | Atmospheric Research Center |
| SARA | Satellite Pour Astronomie Radio Amateur | - | Atmospheric Research Center |
| SAREX | Search And Rescue Exercise / Shuttle Amateur Radio Experiment | - | Atmospheric Research Center |
| SAS | Space Activity Suit / Space Adaptation Syndrome | - | Atmospheric Research Center |
| SAT | Synthetic Aperture Telescope | - | Atmospheric Research Center |
| SB | Spiral | - | Atmospheric Research Center |
| SBIR | Small Business Innovation Research | - | Atmospheric Research Center |
| SCA | Shuttle Carrier Aircraft | - | Atmospheric Research Center |
| SCT | Schmidt-Cassegrain Telescope | - | Atmospheric Research Center |
| SDI | Strategic Defense Initiative | - | Atmospheric Research Center |
| SDIO | Strategic Defense Initiative Organization | - | Atmospheric Research Center |
| SDSS | Sloan Digital Sky Survey | - | Atmospheric Research Center |
| SECO | Sustainer Engine Cutoff | - | Atmospheric Research Center |
| SEDS | Students For The Exploration And Development Of Space | - | Atmospheric Research Center |
| SEI | Space Exploration Initiative | - | Atmospheric Research Center |
| SEM | Space Environment Monitor | - | Atmospheric Research Center |
| SEP | Societe Europeenne De Propulsion | - | Atmospheric Research Center |
| SEPAC | Space Experiments With Particle Accelerators | - | Atmospheric Research Center |
| SEST | Swedish ESO Submillimeter Telescope | - | Atmospheric Research Center |
| SETI | Search For ExtraTerrestrial Intelligence | - | Atmospheric Research Center |
| SHARE | Space Station Heat Pipe Advanced Radiator Element | - | Atmospheric Research Center |
| SID | Sudden Ionospheric Disturbance | - | Atmospheric Research Center |
| SIR | Shuttle Imaging Radar | - | Atmospheric Research Center |
| SIRTF | Space InfraRed Telescope Facility | - | Atmospheric Research Center |
| SIXA | Silicon X-ray Array | - | Atmospheric Research Center |
| SL | (Comet) Shoemaker-Levy / SpaceLab | - | Atmospheric Research Center |
| SL-J | SpaceLab Japan | - | Atmospheric Research Center |
| SLAP | Space Link Access Protocol | - | Atmospheric Research Center |
| SLAR | Side-Looking Airborne Radar | - | Atmospheric Research Center |
| SLC | Space Launch Complex | - | Atmospheric Research Center |
| SLF | Shuttle Landing Facility | - | Atmospheric Research Center |
| SLS | Space(lab) Life Sciences | - | Atmospheric Research Center |
| SMC | Small Magellanic Cloud | - | Atmospheric Research Center |
| SME | Solar Mesosphere Explorer | - | Atmospheric Research Center |
| SMEX | Small EXplorers | - | Atmospheric Research Center |
| SMM | Solar Maximum Mission | - | Atmospheric Research Center |
| SMS | Shuttle Mission Simulator | - | Atmospheric Research Center |
| SN | SuperNova | - | Atmospheric Research Center |
| SNG | Sodruzhestva Nezabisimikh Gosudarst | - | Atmospheric Research Center |
| SNR | Signal To Noise Ratio / SuperNova Remnant | - | Atmospheric Research Center |
| SNU | Solar Neutrino Units | - | Atmospheric Research Center |
| SOB | Strap-On Booster | - | Atmospheric Research Center |
| SOCC | Satellite Operations Control Center | - | Atmospheric Research Center |
| SOFI | Spray-on Foam Insulation | - | Atmospheric Research Center |
| SOFIA | Stratospheric Observatory For Infrared Astronomy | - | Atmospheric Research Center |
| SOHO | SOlar Heliospheric Observatory | - | Atmospheric Research Center |
| SOLSTICE | Solar Stellar Irradiance Comparison Experiment | - | Atmospheric Research Center |
| SPAN | Space Physics And Analysis Network | - | Atmospheric Research Center |
| SPARTAN | Shuttle Pointed Autonomous Research Tool For Astronomy | - | Atmospheric Research Center |
| SPAS | Space Pallet Satellite | - | Atmospheric Research Center |
| SPDM | Special Purpose Dextrous Manipulator | - | Atmospheric Research Center |
| SPH | Smoothed-Particle Hydrodynamics | - | Atmospheric Research Center |
| SPOT | Systeme Probatoire Pour L'Observation De La Terre | - | Atmospheric Research Center |
| SPS | Solar Power Satellite | - | Atmospheric Research Center |
| SPTN | SPARTAN | - | Atmospheric Research Center |
| SR | Special Relativity | - | Atmospheric Research Center |
| SRB | Solid Rocket Booster | - | Atmospheric Research Center |
| SRM | Solid Rocket Motor | - | Atmospheric Research Center |
| SSBUV | Shuttle Solar Backscatter Ultraviolet Experiment | - | Atmospheric Research Center |
| SSCE | Solid Surface Combustion Experiment | - | Atmospheric Research Center |
| SSF | Space Station Freedom | - | Atmospheric Research Center |
| SSI | Solid-State Imager / Space Studies Institut | - | Atmospheric Research Center |
| SSME | Space Shuttle Main Engine | - | Atmospheric Research Center |
| SSO | Spurious Shut-off | - | Atmospheric Research Center |
| SSPF | Space Station Processing Facility | - | Atmospheric Research Center |
| SSPO | Space Shuttle Program Office | - | Atmospheric Research Center |
| SSPS | Sky Survey Prototype System | - | Atmospheric Research Center |
| SSRMS | Space Station Remote Manipulator System | - | Atmospheric Research Center |
| SSRT | Single Stage Rocket Technology | - | Atmospheric Research Center |
| SSRV | Solar-Sail Race Vehicle | - | Atmospheric Research Center |
| SST | Spectroscopic Survey Telescope / SuperSonic Transport | - | Atmospheric Research Center |
| SSTO | Single Stage To Orbit | - | Atmospheric Research Center |
| STARCAL | Star Calibration | - | Atmospheric Research Center |
| STC | Stennis Test Center | - | Atmospheric Research Center |
| STC | SHAPE Technical Center | - | Atmospheric Research Center |
| STDCE | Surface Tension Driven Convection Experment | - | Atmospheric Research Center |
| STIKSCAT | Stick Scatterometer | - | Atmospheric Research Center |
| STIS | Space Telescope Imaging Spectrometer | - | Atmospheric Research Center |
| STS | Shuttle Transport System / Space Transportation System | - | Atmospheric Research Center |
| STSCI | Space Telescope Science Institute | - | Atmospheric Research Center |
| STSDAS | Space Telescope Science Data Analysis System | - | Atmospheric Research Center |
| SUSIM | Solar Ultraviolet Spectral Irradiance Monitor | - | Atmospheric Research Center |
| SWAN | Solar Wind Anisotropy Experiment | - | Atmospheric Research Center |
| SWAS | Submillimeter Wave Astronomy Satellite | - | Atmospheric Research Center |
| SWF | ShortWave Fading | - | Atmospheric Research Center |
| SWLC | Salt Water Leak Check | - | Atmospheric Research Center |
