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Italsat F1 is a communication satellite sponsored by the Italian Space Agency and developed by Alenia Spazio. The spacecraft consists with a platform, which provides all the required services, and three payloads: a global beam package, a multibeam package for domestic communication services at 20/30 GHz, and an experimental propagation package at 40/50 GHz which embraces the European continent. Italsat F1 was sent off by an Ariane IV launcher from the Kourou Space Center in French Guyana on January 16th,1991, and it has been operating since February 1991. Having gone through a complete cycle of solstices and equinoxes, Italsat experienced the extreme environmental conditions at its beginning of life. The flight data collected throughout the first year of operational life enabled a review of the spacecraft thermal performances. This paper presents an overview of in-orbit observed temperatures.

This Paper summarizes the main results of the firing operations performed by the Liquid Apogee Engine (LAE) of ITALSAT F1 spacecraft that has been launched Jan. 15,91. This evaluation represents the final check step of the thermal design activities on the LAE & Thermal Shield Assembly and of the firing control strategy definition presented on the Paper: “Thermal Design, testing and firing control strategy of the Liquid Apogee Engine & thermal Shield Assembly for the ITALSAT program” included in the SAE's 20th ICES conference (1990). The ITALSAT mission has been characterized by two LAE firing operations to place the spacecraft in the final geosynchronous orbit; each firing duration being about 37 minutes.

The thermal control design of the Italian Satellite (ITALSAT) has been experimentally qualified by means of a solar simulation test performed on a dedicated structural/thermal model. The test model was thermally representative of the flight unit and all the thermal hardware was flight standard. Thermal analysis in the test conditions have been performed in order to verify the thermal mathematical models of the spacecraft. The paper describes the tested spacecraft model and the test approach. Test results, correlation with predicted temperatures as well as influences of test conditions on spacecraft test temperatures are presented and discussed.

A failure during the Liquid Apogee Engine (LAE) firing with Thermal Shield, forced Selenia Spazio to critically review the thermal design concept of the LAE/Shield Assembly of ITALSAT Program. This review led to: the change of Thermal Shield design criteria (in order to increase the safety margin on the LAE firing temperatures); the identification of thermal failure modes of the utilized LAE (together with the contribution of many other US and European LAE utilizers and of LAE Supplier as well); the definition and implementation of a LAE Firing Control Strategy. This Paper describes the performed efforts and the resulting engineering considerations.