| Abbreviation | Definition |
|---|---|
| ATMS | Advanced Technology Microwave Sounder |
| ATO | Abort to Orbit |
| ATO | Abort-To-Orbit |
| ATP | Accelerated Training Program |
| ATP | Acceptance Test Procedure |
| ATP | Authorization To Proceed |
| ATR | Above The Rest |
| ATSC | AlliedSignal Technical Services Corporation |
| ATTCS | Automatic Takeoff Thrust Control System |
| ATU | Across The Universe |
| ATV | Advanced Tether Vehicle |
| ATV | Agena Target Vehicle |
| ATV | Automated Transfer Vehicle |
| AU | Astronomical Unit |
| AUDS | ALFA Ultra Deep Survey |
| AUS | Advanced Upper Stage |
| AUSEP | Affordable Upper Stage Engine Program |
| AVC | Automatic Vector Control |
| AVD | Alternate Voice/Data |
| AVS | Air Valve Secondary |