Inertial Upper Stage
 Painting of Ulysses deploying from the Space Shuttle | |
| Manufacturer | Boeing United Technologies |
|---|---|
| Country of origin | United States |
| Used on | Space Shuttle Titan 34D Titan IV |
| General characteristics | |
| Height | 5.2 m (17 ft) |
| Diameter | 2.8 m (9 ft 2 in) |
| Gross mass | 14,700 kg (32,400 lb) |
| Associated stages | |
| Derivatives | TOS |
| Launch history | |
| Status | Retired |
| Total launches | 24 |
| Successes (stage only) | 21 |
| Failed | 2 |
| Lower stage failed | 1 |
| First flight | 30 October 1982 |
| Last flight | 14 February 2004 |
| First stage | |
| Height | 3.15 m (10.3 ft) |
| Diameter | 2.34 m (7 ft 8 in) |
| Gross mass | 10,400 kg (22,900 lb) |
| Propellant mass | 9,700 kg (21,400 lb) |
| Powered by | Orbus-21 |
| Maximum thrust | 190 kN (43,000 lbf) |
| Specific impulse | 295.5 s (2.898 km/s) |
| Burn time | up to 150 seconds |
| Propellant | Solid |
| Second stage | |
| Height | 1.98 m (6 ft 6 in) |
| Diameter | 1.60 m (5 ft 3 in) |
| Gross mass | 3,000 kg (6,600 lb) |
| Propellant mass | 2,700 kg (6,000 lb) |
| Powered by | Orbus-6 |
| Maximum thrust | 80 kN (18,000 lbf) |
| Specific impulse | 289.1 s (2.835 km/s) |
| Propellant | Solid |
The Inertial Upper Stage (IUS), originally designated the Interim Upper Stage, was a two-stage, solid-fueled space launch system developed by Boeing for the United States Air Force beginning in 1976 for raising payloads from low Earth orbit to higher orbits or interplanetary trajectories following launch aboard a Titan 34D or Titan IV rocket as its upper stage, or from the payload bay of the Space Shuttle as a space tug.