Estimating the scale of Space Resource Utilisation (SRU) operations to satisfy lunar oxygen demand

Abstract

The production of oxygen from lunar regolith is analogous to metal production from ore in a terrestrial mine. The process flowsheets both include excavation, haulage and beneficiation of the regolith or ore to provide the feedstock for the chemical extraction of oxygen or metal. The production rate of oxygen depends on the mass rate of regolith treated and the efficiency of converting the regolith to oxygen. To date, the development of Space Resource Utilisation (SRU) has been concerned with the technological development of the process, particularly the excavation and oxygen extraction. However, the required operating mass rates of the mine operation and the oxygen extraction stage have not been considered in any great detail.Previous estimates of mining scale for lunar oxygen production are reviewed, and converted to a comparable regolith mining rate of kg/h. Beneficiation of the regolith before oxygen extraction is considered, and the effects of pre-sizing and removal of a specific component, agglutinates, are considered. The oxygen yield and operational availability are also included. It is estimated that the minimum mining rate to produce 1000 kg of oxygen per annum is at least five times higher than previous estimates, 30 kg/h, for equivalent efficiency assumptions. 2Monte-Carlo simulations were performed for statistical confidence in the estimates of the mining mass rate and the required oxygen extraction feedstock rate. To be 95% confident that the kg/y O2 will be met, the designed mining rate should be at least 65 kg/h, and the beneficiated feedstock rate 16 kg/h. This study has revised and increased the estimate of the lunar regolith mining scale required for the production of a given amount of oxygen. It has also estimated the mass rate of feedstock required for oxygen extraction, if the regolith is first beneficiated.The findings have a significant impact on the practical implementation of lunar mining and oxygen extraction, particularly the process design and whether the operation will be by batch-or continuous processing. The mass scale and beneficiation approaches bring terrestrial mining and processing concepts to SRU, and for the first time estimates the effect that regolith beneficiation and uncertainty have on the estimated scale of both the mining and extraction operations.

Toward the utilisation of resources in space: knowledge gaps, open questions, and priorities

“…Space resource utilisation requires engineering solutions to produce a reliable supply of usable products from a naturally variable feedstock 77 . The use of mineral resources for SRU remains untested anywhere in space, however this will change in the coming years with demonstration missions (e.g.…”

“…Regolith properties, such as size distribution, texture, cohesiveness, electrostatic charge and mineralogy, will be of interest 85 , 86 . The minimum amount of data to increase the geological certainty of a deposit and how it is collected should also be considered 77 , 78 , 80 , 81 . The use of such datasets in fundamental scientific studies (e.g.…”

“…energy use, required throughput, expected efficiency, etc.) will affect equipment designs significantly 77 ). The success of large-scale resource utilisation processes is dependent therefore on a sufficient knowledge of the specific resource and region of interest, as well as the technology capability required to extract useful products.…”

A universal framework for Space Resource Utilisation (SRU)

“…Table 4a in Heiken (1975) Ideally, the variability in regolith properties will also be available, so that confidence intervals can be ascribed. The average and possible ranges of size fractions and minerals properties ultimately define the detailed process design, and allow sensitivity analyses of the extraction stage to feedstock properties, as discussed in Cilliers et al (2019). Such data is available, for example the Lunar Sourcebook (Heiken et al, 1991) details the modal (volume %) abundance data in the 90 to 1000 m size fraction of representative soils (Table 7.2 therein, originally from Simon et al, 1981).…”

Ultra‐High Temperature Molten Oxide Electrochemistry

“…Apparently, low‐carbon metallurgy by UTE could contribute to the goal of carbon neutrality. At the same time, lunar exploration has been a topic of intense interest worldwide during the past 50 years, and scientific research stations on the Moon are expected to be built before 2040 [50–53] . A reliable O 2 supply is a fundamental prerequisite the long‐term duty of personnel.…”