| Abbreviation | Definition |
|---|---|
| OSS | Orbiting Space Station |
| OSSA | Office of Space Science and Applications |
| OSSE | Oriented Scintillation Spectrometer Experiment |
| OSSRH | Orbiter Sub-System Requirements Handbook |
| OST | Operations Support Team |
| OST | Orbiter Support Trolley |
| OSTA | Office of Space and Terrestrial Applications |
| OSTDS | Office of Space Tracking and Data Systems |
| OSTO | Office of Space Transportation Operations |
| OSTP | Orbiting System Test Plan |
| OSTS | Office of Space Transportation Systems |
| OT | Operating Time |
| OT | Operational Instrumentation MDM (Manipulator Deployment Mechanism) -Tank |
| OT | Operational Instrumentation MDM-Tank |
| OT | Operational Test |
| OT | Operational Trajectory |
| OT | Optical Tracker |
| OT | Out Temperature |
| OTA | Optical Telescope Assembly |
| OTB | Orbiting Tanker Base |