The Inertial Upper Stage (initially known as the Interim Upper Stage) was a two-stage solid-propellant upper stage combination used for high-energy orbital insertions of satellites launched aboard the Space Shuttle and Titan rocket. The first stage was composed of an Orbus-21 solid rocket motor and a metallic interstage structure; the second stage was built around an Orbus-6E SRM and also contained the avionics and attitude control/orbit trimming thrusters used for the combined assembly.

IUS was initially intended as a temporary stage to support Shuttle-based satellite launches to geosynchronous orbit prior to the development of Shuttle-Centaur. Following the Challenger disaster, Shuttle-Centaur was canceled, and IUS was used for all remaining missions of this type. IUS also flew several times on the Titan-34D and Titan IV expendable launch vehicle, offering performance in between the basic no-upper-stage and Titan-Centaur variants. A few other upper stages were developed or proposed based on IUS components, such as the Transfer Orbit Stage.

All materials and textures are packed into the .blend file. Instancing and modifiers have been used to reduce file size and enable easy editing. A zip file containing image textures is also included

Changelog:

November 13 2023: Initial upload

Jan 27 2025: Added 3d printable STL version