| Acronym | Meaning |
| FAP | Freedom Attached Payloads |
| AFWTR | USAF's WTR |
| HTHL | Horizontal Takeoff Horizontal Landing |
| DSSC | Deep Space Station Complex |
| RKA | Rossiskoye Kosmicheskoye Agentsvo |
| CDDT | Countdown Demonstration Test |
| ACR | Active Cavity Radiometer |
| NSF | National Science Foundation |
| EUV | Extreme UltraViolet |
| HRSC | High Resolution Stereo Camera |