Evolution of Regolith Feed Systems for Lunar ISRU 02 Production Plants

The In-Situ Resource Utilization (ISRU) project of the NASA Constellation Program, Exploration Technology Development Program (ETDP) has been engaged in the design and testing of various Lunar ISRU O2 production plant prototypes that can extract chemically bound oxygen from the minerals in the lunar regolith. This work demands that lunar regolith (or simulants) shall be introduced into the O2 production plant from a holding bin or hopper and subsequently expelled from the ISRU O2 production plant for disposal. This sub-system is called the Regolith Feed System (RFS) which exists in a variety of configurations depending on the O2 production plant oxygen being used (e.g. Hydrogen Reduction, Carbothermal, Molten Oxide Electrolysis). Each configuration may use a different technology and in addition it is desirable to have heat recuperation from the spent hot regolith as an integral part of the RFS. This paper addresses the various RFS and heat recuperation technologies and system configurations that have been developed under the NASA ISRU project since 2007. In addition current design solutions and lessons learned from reduced gravity flight testing will be discussed.