The Moon: Our Next Frontier
In the near future, Artemis 3 will embark on a historic mission to land humans on the Moon. This endeavor, set for 2025, will mark the first manned lunar exploration since the Apollo era. To combat the challenges posed by the Moon’s harsh environment, a team of international researchers from the European Space Agency’s (ESA) PAVER project has developed a groundbreaking method to utilize lasers in melting lunar soil, known as Moondust, or a similar stimulant for it. This innovative technique enables the creation of interlocking pavers that can be used for constructing paved roads and landing pads on the Moon. The hardened molten regolith possesses the strength to withstand the weight of rovers and spacecraft, while minimizing the release of lunar dust.
According to the researchers, this cutting-edge technology is expected to play a significant role in the initial phase of lunar infrastructure and base development. Over time, it has the potential to contribute to all stages of lunar exploration. Their findings were recently published in a study featured in Scientific Reports.
Scratching the Surface
The presence of Moondust poses a significant challenge for lunar missions. On Earth, the weathering forces of wind, rain, and water cause materials in the soil, such as rock and glass, to smooth out over time. However, lunar regolith remains unweathered due to the absence of wind and liquid water on the Moon. Consequently, any spacecraft or astronaut that encounters this dust is susceptible to damage, as the sharp particles of unweathered rock and glass can scratch sensitive instruments and surfaces. Additionally, the Moon’s low gravity allows these perturbed shards to freely disperse and infiltrate various components.
To address this issue, the PAVER scientists devised a method to utilize existing resources on the Moon for creating paving materials. Given the cost and inconvenience of shipping supplies from Earth, the researchers advocated for in-situ production whenever possible.
Stepping Stones
To determine the optimal laser settings for producing the most durable paving material, the scientists conducted experiments using different sizes and strengths of laser beams. During this process, they discovered that the crossing or overlapping of laser beams could result in internal cracking, especially considering that lunar regolith contains glass and other silicates. Ultimately, a laser with a beam size of 45 mm (approximately 1.8 inches) proved to be the most effective. By moving in a specific pattern, it melted the regolith or simulant into triangular pieces measuring 250 mm (nearly 10 inches) in size and 15 mm (slightly over half an inch) in thickness. These triangular pavers easily interlock with one another. However, it is important to note that scaling up is necessary to accommodate actual spacecraft in future lunar operations.
The irradiated and cooled regolith exhibited three distinct layers. The top layer consisted of a glass-like substance, while the middle layer contained crystallized material that had also been melted. Finally, the thin bottom layer resulted from sintering, a process in which dust particles bind together to form a porous mass. Although this material possessed sufficient density and strength, the scientists designed geometric shapes to maximize flexibility and resistance to cracking or breakage.
Compression tests were conducted on the triangular pavers to assess their ability to withstand spacecraft weight. The highest recorded pressure before breakage was 216.29 megapascals, which is slightly over 30,000 pounds per square inch. For comparison, the Apollo lunar module weighed 33,000 pounds, and its weight was distributed over a significantly larger surface area than that of a single inch.
The researchers acknowledge that further advancements are necessary in this field. For instance, testing the effectiveness of a lens to concentrate sunlight, in place of a laser, on the Moon is recommended. However, due to the minimal equipment required for this process on the Moon, there is potential to swiftly implement these tests and potentially restore humans’ ability to walk on the Moon, following the footsteps of Apollo 17.
Citation: Scientific Reports, 2023. DOI: 10.1038/s41598-023-42008-1
