| Abbreviation | Definition |
|---|---|
| ITS | Instrumentation Telemetry Station |
| ITS | Interim Teleprinter System |
| ITSC | Imaging Technology Space Center |
| IU | Instrument Unit |
| IUA | Inertial Unit Assembly |
| IUA | Interface Unit Adapter |
| IUCS | Instrumentation Unit Update Command System |
| IUCS | Instrumentation Update Command System |
| IUE | Interface Unit Error-count table |
| IUE | International Ultraviolet Explorer |
| IUS | Inertial Upper Stage |
| IUS | Inertial Upper Stage (was Interim Upper Stage) |
| IUS | Interim Use Sheet |
| IUS | Interim/Intermediate Upper Stage |
| IUS | Interior Upper Stage |
| IUS | International Ultrasonics Symposium |
| IUS | Inter-University Seminar |
| IV | Initial Velocity |
| IV | Integrated Vehicle |
| IV | Interface Volume |