Lunar Highways: How Lasers Can Transform Moon Dust Into Roads

Lunar Infrastructure: The Role of Lasers in Converting Lunar Regolith into Paved Surfaces

The European Space Agency’s (ESA) PAVER initiative has explored the possibility of generating paved areas on the Moon, such as landing platforms and roadways, by employing the process of lunar regolith melting. While a carbon dioxide laser was utilized for Earth-based experiments, a Fresnel lens would likely be used on the Moon to concentrate sunlight. Credit: Consortium of PAVER/LIQUIFER Systems Group

In an endeavor to address the challenges of lunar dust for upcoming missions, the European Space Agency (ESA) has effectively employed lasers to liquefy simulated lunar soil, thereby laying the foundation for prospective road infrastructure on the Moon.

Given that future lunar explorers are expected to rely more on vehicular travel than on foot, the development of lunar roads becomes imperative to control the dispersion of Moon dust. A recent study published on October 12 in the journal Scientific Reports revealed that ESA tested the generation of durable surfaces on the Moon by using a potent laser to melt simulated lunar soil.

The Imperative for Roads on the Lunar Surface

The emergence of civilization usually brings the development of road networks, a necessity that will be particularly true on the Moon to combat the issue of lunar dust. The dust on the Moon is extremely fine, abrasive, and has a tendency to adhere to surfaces. During the Apollo missions, this dust was responsible for obstructing equipment and causing wear and tear on spacesuits.

It’s worth noting that during the Apollo 17 mission, the lunar rover’s missing rear fender led to dust accumulation that nearly caused the vehicle to overheat. Similarly, the Soviet Union’s Lunokhod 2 rover was incapacitated due to overheating when dust accumulated on its radiator.

Current computational models from NASA suggest that the thruster plumes from landing lunar modules could displace tons of dust, which may not only stick to the landers but also affect the surrounding area.

Creating Paved Areas on the Moon

The most pragmatic solution to address the dust problem is to pave the Moon’s active areas, which include roadways and landing platforms. The concept of melting sand to form roads was originally proposed for Earth in 1933.

The PAVER initiative, spearheaded by Germany’s BAM Institute of Materials Research and Testing, in collaboration with Aalen University in Germany, LIQUIFER Systems Group in Austria, and Clausthal University of Technology in Germany, explored the viability of using this methodology for lunar surface paving. Supported by the Institute of Materials Physics in Space of the German Aerospace Center, DLR, the consortium employed a 12-kilowatt carbon dioxide laser to melt simulated lunar soil into a solid glass-like substance. Through a methodical approach, the team managed to achieve a melt spot size of 5-10 cm and proposed using a 4.5 cm diameter laser beam to create triangular, hollow-centered geometric shapes measuring approximately 20 cm. These shapes could be interlocked to form durable surfaces over extensive lunar areas suitable for roads or landing platforms.

As Advenit Makaya, an ESA materials engineer, elaborates, the actual implementation on the Moon would not involve transporting a carbon dioxide laser. The laser serves merely as a light source for experimentation, standing in for lunar sunlight that would be concentrated via a Fresnel lens for equivalent lunar surface melting.

Research Methods and Findings

Previous experiments in in-situ resource utilization—such as building bricks using concentrated solar heat—focused on relatively small melting spots. However, for the construction of roads and landing pads, a much broader focal point is necessary. The consortium realized that working with regolith was easier at larger spot sizes, as smaller spots led to molten balls that were difficult to aggregate due to surface tension.

Upon reheating, the cooled tracks exhibited a tendency to crack, prompting the team to opt for designs with minimal overlapping paths. A single layer of the melted material was found to be about 1.8 cm deep. Built structures and roads might require multiple layers, dependent on the structural load requirements.

Jens Günster, who leads the Multimaterial Manufacturing Processes Division at BAM, clarified that the achievement of such high depths of melting for substantial structures is possible only through large laser spots. The team estimates that a landing pad of 100 sq. m, with a 2 cm thickness of dense material, could potentially be completed in 115 days.

Project Origin and Future Directions

The PAVER project originated from a call for proposals by the Discovery element of ESA’s Basic Activities through the Open Space Innovation Platform (OSIP). This call targeted research pertaining to extraterrestrial manufacturing and construction and received 69 responses. Of these, 23 were implemented following an assessment by a panel of ESA experts based on the novelty of the ideas.

In the eyes of Advenit Makaya, this initial call has proven to be a fruitful investment, as it has unveiled numerous promising avenues for further investigation.

Reference: “Laser Melting Manufacturing of Large Elements of Lunar Regolith Simulant for Paving on the Moon” by Juan-Carlos Ginés-Palomares, Miranda Fateri, Eckehard Kalhöfer, Tim Schubert, Lena Meyer, Nico Kolsch, Monika Brandić Lipińska, Robert Davenport, Barbara Imhof, René Waclavicek, Matthias Sperl, Advenit Makaya and Jens Günster, published on 12 October 2023 in Scientific Reports.
DOI: 10.1038/s41598-023-42008-1

Frequently Asked Questions (FAQs) about lunar road construction

More about lunar road construction

• European Space Agency’s Official Website
• Scientific Reports Journal Publication on PAVER
• BAM Institute of Materials Research and Testing
• Clausthal University of Technology Research Facilities
• Institute of Materials Physics in Space of the German Aerospace Center
• Open Space Innovation Platform (OSIP)
• Lunar Regolith and its Challenges in Space Missions