Space station biomining experiment demonstrates rare earth element extraction in microgravity and Mars gravity

Area of Science:

• Astrobiology
• Mining Engineering
• Microbiology

Background:

• Microorganisms are utilized for extracting valuable elements, including rare earth elements (REEs), essential for modern industries.
• Space exploration necessitates in-situ resource utilization (ISRU) for sustainable human presence and industrial activities.
• Bioleaching offers a potential method for extracting resources from extraterrestrial geological materials.

Purpose of the Study:

• To investigate the efficacy of bioleaching for rare earth element (REE) extraction from basalt in microgravity and simulated Martian and Earth gravities.
• To evaluate the performance of a novel biomining reactor under varying gravitational conditions.
• To determine the microbial specificity of REE bioleaching across different gravity environments.

Main Methods:

• An experiment was conducted on the International Space Station using a custom-designed biomining reactor.
• Three distinct microorganisms (Sphingomonas desiccabilis, Bacillus subtilis, and Cupriavidus metallidurans) were tested for their ability to leach REEs from basaltic rock.
• Bioleaching efficiency was compared across microgravity, simulated Mars gravity, and simulated Earth gravity conditions against non-biological controls.

Main Results:

• Sphingomonas desiccabilis demonstrated enhanced REE leaching across all tested gravity conditions compared to controls.
• No significant variations in final REE yields were observed between microgravity and simulated gravity conditions, indicating process robustness.
• Bacillus subtilis showed reduced bioleaching efficacy, while Cupriavidus metallidurans exhibited no significant difference from controls, highlighting microbial specificity.

Conclusions:

• Space-based biomining is a viable strategy for extracting valuable elements like REEs from extraterrestrial resources.
• The designed biomining reactor is effective in microgravity and simulated gravities, supporting potential off-world industrial applications.
• Microbial selection is crucial for successful space biomining, as efficacy varies between species and is consistent with terrestrial performance.