The IRIS system - An Italian STS-upper stage

It is noted that the IRIS class is complementary to the SSUS system, covering performance ranges below the SSUS-D. The IRIS system comprises the expendable IRIS Spinning Stage (ISS) and the reusable Airborne Support Equipment (ASE) for supporting and controlling the ISS stage and the attached spacecraft. The subsystems of the ISS are listed, along with the components of the ASE. It is pointed out that the IRIS system can be employed in conjunction with the STS to perform a wide range of missions compatible with STS performance capabilities. The IRIS nominal mission involves deployment from the Orbiter while at 296 plus or minus 2 km circular orbit (28.5 plus or minus 0.1 deg inclination) and the injection of a 900-kg spacecraft into an elliptical transfer orbit with perigee at nominal Orbiter altitude, apogee at geostationary altitude, and inclination over the equatorial plane of 28.5 deg.