| Acronym | Meaning |
| HTHL | Horizontal Takeoff Horizontal Landing |
| APT | Automatic Photoelectric Telescope |
| ESRO | European Space Research Organisation |
| NRO | National Reconnaissance Office |
| CASSINI | Saturn Orbiter And Titan Probe |
| ACF | Automated Control Function |
| HRPT | High Resolution Picture Transmission |
| HTVL | Horizontal Takeoff Vertical Landing |
| ECS | Environmental Control System |
| STIKSCAT | Stick Scatterometer |