Researchers have determined that lunar soil contains approximately 43% oxygen in the lunar soil oxides, which could be extracted to provide breathable oxygen for consumption by astronauts. The proposed program will develop a solar receiver for the hydrogen reduction process that uses sodium heat pipes in the 1050o
C temperature range. The heat pipe solar receiver is accepts the non-uniform solar thermal energy, and deliver the energy to the lunar regolith with a uniform heat flux and temperature. This increases throughput and efficiency. The principal Phase II program objective is to design, fabricate, and demonstrate a heat pipe solar receiver in a relevant environment and near optimum configuration. While the Phase I program focused on a single heat pipe solar receiver and regolith reactor, the Phase II program will examine variable-conductance or pressure-controlled heat pipes to supply the heat supplied from a single receiver to multiple reactors. The program will examine control schemes to vary the heat supplied to each reactor, hydrogen permeation, and evaluation of the heat pipe wall materials.