IRIS - A new Italian upper stage system

IRIS (Italian Research Interim Stage) is designed to launch a satellite having a maximum weight of 900 kg from the Space Shuttle. IRIS comprises two modules. One is the Airborne Support Equivalent (ASE), which is mounted in the cargo bay of the Shuttle and supports the deployable stage module and the payload during the ground operations, the launch, and the ascent to the on-orbit separation. The other module is the IRIS Spinning State (ISS), a deployable and expendable stage carrying the payload to be launched; the ISS is spin stabilized and has a solid rocket motor whose ignition allows the payload transfer orbit insertion. The reusable ASE consists of a cradle in a truss structure for mounting the deployable stage with its payload inside the Shuttle cargo bay. The cradle has four lateral attachment fittings and one keel fitting, the latter positioned on the rear part.