| Abbreviation | Definition |
|---|---|
| SST | Single System Trainer |
| SST | Spacecraft Systems Test |
| SST | Structural Static Test |
| SST | Subsystem Terminal on Spacelab |
| SSTC | Space Shuttle Test Conductor |
| SSTF | Space Station Training Facility |
| SSTG | Space Shuttle Task Group |
| SSTO | Single Stage To Orbit |
| SSU | Space Science Update |
| SSU | Space Station Utilization Office |
| SSU | Star Sensor Unit |
| SSUS | Spinning Solid Upper Stage |
| SSUS-A | Spinning Solid Upper Stage for Atlas-Centaur class Spacecraft |
| SSUS-A | SSUS for Atlas-Centaur Class Spacecraft |
| SSUS-D | Spinning Solid Upper Stage for Delta class Spacecraft |
| SSUS-D | SSUS for Delta Class Spacecraft |
| SSUSP | Spinning Solid Upper Stage Project |
| SSV | Space Shuttle Vehicle |
| SSV | Station Support Vehicle |
| SSWG | Solar System Working Group |