| Abbreviation | Definition |
|---|---|
| ASM | Attached Synchronization Marker |
| ASP | Attitude Sensor Package |
| ASRS | Automated Support Requirements System |
| AST | Aero Space Technology |
| AST | Astro Star Tracker |
| ASTER | Advanced Spaceborne Thermal Emission and Reflection |
| ASTER | Advanced Spaceborne Thermal Emission and Reflection Radiometer |
| ASTG | AeroSpace Test Group |
| ASTID | ASTrobiology Instrument Developement program |
| ASW | Address and Synchronization Word |
| ASW | Application SoftWare |
| AT | Acceptance Testing |
| ATC | Absolute Time Command |
| ATCS | Active Thermal Control System |
| ATE | Automated Test Equipment |
| ATLAS | ATmospheric Laboratory for Applications and Science |
| ATLIT | Advanced Technology Light Twin-Engine airplane |
| ATLO | Assembly, Test, and Launch Operations |
| ATM | Atmosphere |
| ATMOS | ATmospheric Trace Molecule Spectroscopy |