Simulated moon soil and recyclable thermoplastics could help build future space infrastructure

Transporting resources to the moon is prohibitively costly, with estimates suggesting a single kilogram could incur expenses exceeding $1 million. Consequently, future human settlements on the lunar surface hinge on reducing these expenditures. Engineers and designers have often considered lunar regolith—a granular, abrasive material covering the lunar surface—as a potential abundant resource.

A recent study from Concordia University demonstrates how integrating recycled high-performance thermoplastics with simulant lunar regolith can create composite materials suitable for in-situ additive manufacturing on the moon.

The researchers synthesized a composite utilizing lunar regolith simulant and a high-performance recycled thermoplastic, poly(ether ketone ketone) (PEKK). They successfully employed this composite to 3D print sacrificial structures intended to absorb energy and deform under load, rather than as permanent components. These sacrificial elements enabled the researchers to evaluate the composite's capacity to endure stresses akin to those a lunar module's landing mechanism would experience upon impact.

Additionally, they manufactured a wrench from the composite material. The findings revealed that incorporating lunar regolith simulants mitigated shrinkage and warping during heat treatment—an advantageous attribute for on-site manufacturing, given the limited access to processing equipment on the moon.

Notably, the PEKK material utilized in these experiments had been previously recycled from a sacrificial structure, illustrating the feasibility of processing and reusing recycled materials while preserving their thermal and mechanical properties. This material was processed through three recycling cycles without manifesting substantial degradation or loss of its structural and mechanical attributes.

The recycled PEKK was pulverized into powder, dried, and subsequently combined with a commercially accessible lunar regolith simulant to form filament, which was then utilized for 3D printing.

The composite underwent rigorous testing, including evaluations under heat, stretching, bending, and compression. The study also performed a heat treatment to assess the composite's performance under additional processing conditions. The results indicated that the recycled composite exhibited thermal stability, and the particles of regolith were uniformly dispersed throughout the plastic matrix.

Incorporating regolith simulants also diminished the crystallization temperature of PEKK during heating, thereby enhancing the efficiency of the heat treatment process. However, the composite demonstrated increased porosity compared to pure PEKK, leading to a more brittle structure. The researchers emphasized that the recycled PEKK polymer underwent no degradation during this process.

This research represents one of the initial endeavors demonstrating a closed-loop system that integrates the recycling of high-performance polymers for space applications with lunar regolith. While the technology remains relatively nascent, it offers a promising avenue for optimizing the utilization of limited resources in space exploration endeavors. The findings were published in the journal Composites Part B: Engineering by Farshad Malekpour and Mehdi Hojjati.