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Boeing Inertial Upper Stage Space Payload Booster

The IUS and the Defense Support Program (DSP) satellite are stacked together in the 4th BLDG Space Gallery.

The Inertial Upper Stage (IUS) is an unpiloted upper-stage booster rocket used from 1982-2004. After launch on an unmanned rocket or inside a space shuttle, the IUS boosted its payload into a higher orbit or sent planetary and solar probes on their way through space.

Twenty-four IUS vehicles were launched. Inertial Upper Stages flew with nine Defense Support Program (DSP) satellites plus a variety of other defense satellites. Other notable IUS launches included the Magellan spacecraft to Venus in 1988 and, in 1990, the Galileo probe to Jupiter and the Ulysses orbiter to the sun. The Chandra X-ray observatory also used an IUS on its 1999 launch. When the Space Shuttle Challenger was lost in 1986, the accident also destroyed an IUS carrying a NASA Tracking and Data Relay Satellite.

Typically, when boosting a satellite, an IUS launched aboard a Titan IVB rocket like the one in the museum's Space Gallery. It then separated from the rocket about nine minutes after launch. The IUS would carry its satellite for the next 6-7 hours, performing all the functions needed to place the satellite in a geosynchronous orbit about 22,300 miles above the Earth. In placing a DSP satellite into orbit, the IUS performed two rocket burns, about one hour and then six and a half hours into its flight. After that, the satellite separated from the IUS as the vehicle reached its proper orbit.

32,500 lbs. (vehicle 5,100 lbs., propellant 27,400 lbs.)

Propulsion: Two solid-fuel rockets. First stage 45,600 lbs. thrust with 21,400 lbs. propellant; second stage 18,500 lbs. thrust with 6,000 lbs. propellant
Launch vehicles: Space Shuttle, Titan 34D, Titan IVA, Titan IVB
Boost capability: 5,000 lb. payload to geosynchronous orbit or up to 8,000 lbs. beyond Earth’s gravitational field

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