| Abbreviation | Definition |
|---|---|
| RIT | Request for Interface Tool |
| RIU | Remote Interface Unit |
| RIV | Recirculation Isolation Valve |
| RJ | Radius of Jupiter |
| RJ/EC | Reaction Jet/Engine Control |
| RJC | Reaction Jet Control |
| RJD | Reaction Jet Device |
| RJD | Reaction Jet Driver |
| RJDA | Reaction Jet Driver Aft |
| RJDF | Reaction Jet Driver Forward |
| RJEC | Reaction Jet Engine Control |
| RJOD | Reaction Jet OMS Driver |
| RK | Recharge |
| RK | Re-charge |
| RKD | Rocketdyne |
| RL | Return Link |
| RLA | Repair Level Analysis |
| RLA | Repair Line Agreement |
| RLBV | Reusable Lifting Body Vehicle |
| RLC | Remote Load Controller |