Galileo probe battery system

NASA's pair of Galileo spacecraft arrived at Jupiter on 7 December 1995. The Probe descended into the upper Jovian atmosphere, performing its planned sequence of scientific measurements of the properties of that medium for about an hour. This Probe has been the most ambitious planetary entry vehicle to date. It evolved over several years of planning and construction, its launch was postponed many times, for a variety of reasons; and it required more than 6 years of travel after launch to reach the planet. Its electrical power was provided by a primary Li-SO₂ battery, supplemented with two thermal batteries (CaCrO₄-Ca) used for firing pyrotechnic initiators during the atmospheric entry. These power sources were designed to be robust, to assure they would perform their intended function after surviving several years in space. This paper discusses the final production, qualification, and the systems testing of these batteries prior to and following launch. Their excellent performance at Jupiter confirmed their life enhancement design features