Galileo Probe battery system [space power]

This past year, the Galileo Probe successfully completed its ambitious mission-descending into Jupiter´s atmosphere to measure its gaseous properties. This brought to fruition work that had been in progress for 18 years, the last 6 of which were required just for the long transit from Earth to Jupiter. The Probe´s electrical source was a primary Li-SO₂ battery, supplemented with thermally activated batteries. The batteries remained dormant during most of the interplanetary travel time, being activated only as the planet was approached. The battery system worked flawlessly. Energy density, storage life, and ability to turn on suddenly were important factors in applying this battery system. Its success was aided by the extensive testing that occurred before and after launch, as described in this paper