Hybrid lunar ISRU plant: a comparative analysis with carbothermal reduction and water extraction

TL;DR

The study tackles uncertainty in lunar ISRU by evaluating hybrid architectures that co-produce LOX and LH2 from both dry regolith and icy regolith. It introduces two configurations, Parallel Hybrid (PH) and Series Hybrid (SH), in addition to conventional CR and WE plants, and uses end-to-end subsystem models and Monte Carlo simulations to compare landed mass and power. It finds that SH can increase regolith excavation rates but often carries the heaviest mass, while PH offers intermediate Tradeoffs; WE can be mass- and power-intensive under uncertain ice content, and CR remains favorable for short-term light-mass scenarios but relies on Earth-supplied reagents for longer missions. The results emphasize that water ice content uncertainty dominates performance, and hybrid architectures provide valuable information for decision-makers considering future full-scale ISRU deployment.

Abstract

To establish a self-sustained human presence in space and to explore deeper into the solar system, extensive research has been conducted on In-Situ Resource Utilization (ISRU) systems. Past studies have proposed and researched many technologies to produce oxygen from regolith, such as carbothermal reduction and water extraction from icy regolith, to utilize it for astronauts' life support and as the propellant of space systems. However, determining the most promising technology remains challenging due to uncertainties in the lunar environment and processing methods. To better understand the lunar environment and ISRU operations, it is crucial to gather more information. Motivated by this need for information gathering, this paper proposes a new ISRU plant architecture integrating carbothermal reduction of dry regolith and water extraction from icy regolith. Two different hybrid plant architectures integrating both technologies (1) in parallel and (2) in series are examined. The former involves mining and processing in both a Permanently Shadowed Region (PSR) and a peak of eternal light in parallel, while the latter solely mines in a PSR. In this series hybrid architecture, the dry regolith tailings from water extraction are further processed by carbothermal reduction. This paper conducts a comparative analysis of the landed mass and required power of each plant architecture utilizing subsystem-level models. Furthermore, based on uncertain parameters such as resource content in regolith, the potential performance range of each plant was discovered through Monte Carlo simulations. The result indicates the benefit of the series hybrid architecture in terms of regolith excavation rate, while its mass cost seems the highest among the studied architectures.

Figures (23)

• Figure 1: ISRU production plant architectures considered in this paper.
• Figure 2: Flow diagrams of ISRU architectures considered in this paper. Mass flows across subsystems are shown. The diagram blocks crossed out in red are not modeled.
• Figure 3: (Continued.)
• Figure 4: High-level schematic of a parametric sizing CR reactor model.
• Figure 5: CR reactor design. The number of molten areas is the same as the number of solar energy feedthroughs, which affects the dimensions of the reactor.