TSS CORE EQUIPMENT .1. ELECTRODYNAMIC PACKAGE AND RATIONALE FOR SYSTEM ELECTRODYNAMIC ANALYSIS

The first Tethered-Satellite System (TSS-1) Electrodynamic mission has been launched aboard the Space Shuttle STS-46 on July 31, 1992, as a joint mission between the United States and Italy. A 500 kg, spherical Satellite (1.6 m diameter), attached to the Orbiter by a thin (0.24 cm), conducting, insulated wire (Tether), has been reeled upwards from the Orbiter payload bay to a distance of 256 m, rather than the expected 20 km, when the Shuttle was at a projected altitude of 300 km. ASI, the Italian Space Agency, had the responsibility for developing the reusable Satellite, while NASA had the responsibility for developing the Deployer system and the Tether, integrating the payload and providing transportation into space. One of the main scientific goals of this first mission is to demonstrate the possibility of energy conversion from mechanical to electrical by using a long Tether orbiting through the Earth's magnetic field. ASI designed and developed an active experiment, referred to as Core Equipment, in order to carry out this demonstration, and to support all the scientific investigations related to the study of the TSS electrodynamic interactions with the Earth's ionosphere. The experiment uses two Electron Generator Assemblies (EGAs), located on the Orbiter, to re-emit into the ionosphere, as an electron beam, the electrons collected on the Satellite from the ionosphere. Other instruments provide current, voltage, and ambient pressure measurements, and allow, via a series of switches, different electrical configurations of the TSS. The Core Equipment was innovative for space experiments in general and Shuttle experiments in particular. In fact, it was the first flight in which the Shuttle has been used as an integral part of the experiment and not only as an observing platform. It was the first mission with an integrated approach to science, with all the instrumentation and their operative modes selected to characterize the electric properties of the TSS.