| Abbreviation | Definition |
|---|---|
| SPALS | Society for Popular Astronomy Lunar Section |
| SPAM | Special People Admiring Meteors |
| SPARC | Space Physics Aeronomy Research Collaboratory |
| SPARSO | Space Research And Remote Sensing Organization |
| SPC | Short Period Comet |
| SPD | Southern Polar Distance |
| SPTN | Shuttle Pointed Autonomous Research Tool for Astronomy (NASA; aka SPARTAN) |
| SR | Spectral Recording |
| SRAA | Scenic Rim Astronomy Association |
| SS | Shooting Stars |
| SSCP | Simultaneous Stretching and Corona Poling |
| SSDA | Solar System Data Archive |
| SSE | Secret Space Encryptor |
| SSID1 | Soviet Space Insertion Diverter One |
| SSLB | Steady-State Leaky-Box |
| SSO | SpaceShipOne |
| SSS | Solar Single Scattering |
| SST | SpaceShipTwo |
| SSU | Steady State Universe |
| SSWG | Space Science Working Group |