The Oxygen Generator Subsystem (OGS) on the next Mars Lander will demonstrate the production of oxygen from Martian atmospheric carbon dioxide using solid oxide electrolysis. The electrolyzer in OGS is based on a Yttria Stabilized Zirconia electrolyte and operates at 750°C. The electrolyzer is thermally cycled during every sol of operation between Mars ambient and operating temperature with a maximum of 15W electrical power. A package for this electrolyzer has been designed, built, and tested. It meets all the requirements of this experiment and weighs only slightly more than 1kg.