Key: DSCS—Defense Satellite Communications System; TDRS—Tracking and Data Relay System; DSP—Defense Support Program
| Inertial Upper Stage Unclassified Flight History | ||||
|---|---|---|---|---|
| ||||
| Tag no. | Booster | Date | Payload | Notes |
| IUS-2 | Titan-34D | 10/30/1982 | DSCS II/III | 1st IUS; telemetry loss |
| IUS-1 | STS-6/Challenger | 4/4/1983 | TDRS 1 | SRM-2 anomaly |
| IUS-3 | STS-51L/Challenger | 1/28/1986 | TDRS 2 | Shuttle explosion |
| IUS-7 | STS-26R/Discovery | 9/29/1988 | TDRS 3 | IUS return to flight |
| IUS-9 | STS-29/Discovery | 3/13/1989 | TDRS 4 | |
| IUS-18 | STS-30/Atlantis | 5/4/1989 | Magellan | Magellan to Venus |
| Titan IV | 6/14/1989 | DSP 14 | 1st Titan IV | |
| IUS-19 | STS-34/Atlantis | 10/18/1989 | Galileo | Galileo to Jupiter |
| IUS-17 | STS-41/Discovery | 10/6/1990 | Ulysses | Ulysses to solar Polar orbit |
| Titan IV | 11/13/1990 | DSP 15 | ||
| IUS-15 | STS-43/Atlantis | 8/2/1991 | TDRS 5 | |
| STS-44/Atlantis | 11/24/1991 | DSP 16 | ||
| IUS-13 | STS-54/Endeavour | 1/13/1993 | TDRS 6 | |
| IUS-20 | Titan IV | 12/22/1994 | DSP 17 | |
| IUS-26 | STS-70/Discovery | 7/13/1995 | TDRS 7 | |
| IUS-4 | Titan IV | 2/23/1997 | DSP 18 | |
| IUS-21 | Titan IV | 4/9/1999 | DSP 19 | Failed separation of SRM-2 |
| IUS-27 | STS 93/Columbia | 7/23/1999 | Chandra | Chandra Observatory |
| IUS-22 | Titan IV | 5/8/2000 | DSP 20 | |
| IUS-16 | Titan IV | 8/6/2001 | DSP 21 | |
| ||||
Key: DSCS—Defense Satellite Communications System; TDRS—Tracking and Data Relay System; DSP—Defense Support Program | ||||