IRIS system and future application to expandable launchers

The Italian Research Interim Stage (IRIS) is described. It consists of a Shuttle upper stage system designed to inject light payloads up to 900 kg mass from the Shuttle circular parking orbit into a geostationary transfer orbit. A summary of the information included in the IRIS users manual provides users with the necessary performance data, environment and interfaces for their payloads. A review of the status of the project is presented. The first flight unit will be launched in Aug. 1991.