Ice-mining lunar rover using Americium-241 radioisotope power systems

Abstract

Permanently Shadowed Regions (PSRs) of the Moon contain rich deposits of water ice. They are very valuable to the space community as in-situ extracted water can be used for many purposes, such as propellant production and human habitat support. PSR craters never see sunlight, therefore solar power is not available there. They also present a cryogenic environment with regolith as cold as 40 K. These challenges can be overcome by employing a Radioisotope Power System (RPS) to provide both thermal and electrical power to resource extraction systems in the PSRs. The work presented here aims at characterizing an ice-mining lunar rover. The rover will be equipped with an Americium-241 (or 241Am) based RPS. 241Am has a 432-year long half-life and can provide decades of stable power output for the rover operations. The innovation lies in the fact that the RPS will not only provide electrical power to the rover, but that its waste heat will be employed to thermally mine ice from its deposits. The rover is equipped with a sublimation plate irradiating the underlying regolith to sublimate ice contained within, and with a cold trap where extracted volatiles will be deposited. This work studied the rover concept feasibility and developed a model of its Thermal Management System (TMS) to meet sublimation plate and cold trap temperature requirements. The results have been validated by a 3D finite element method thermal simulation for icy regolith conditions of 0–10 vol% water-ice content. The findings of this work suggest that it is possible to perform thermal ice-mining in the lunar PSR environment with an RPS-powered rover, with different degrees of efficiencies depending on the amount of ice in the deposits.