Stone walls planned to be built on Moon with robotic excavators

Swiss researchers have put forward an innovative plan to use autonomous robotic hydraulic excavators to construct dry stone walls on the moon. These walls are intended to act as blast shields, protecting lunar launch pads from rocket exhaust and debris.

The excavators will use materials found on the lunar surface, avoiding the substantial costs of transporting building materials from Earth. The walls will be built using rocks collected on the moon, forming a ring with a radius between 50 and 100 meters. “The robot would be used to both collect the boulders as well as to construct the wall,” explained study lead author Jonas Walther in an interview with Space.com.

Addressing the Challenges of Lunar Construction and Excavation

Walther’s research, initially conducted for his master’s thesis at ETH Zürich, is now supported by Venturi Lab, a Swiss company working on lunar rover design. The idea draws on a terrestrial prototype developed by a team led by Walther’s co-author, Ryan Luke Johns, which used an autonomous robot to build a dry-stone wall on Earth.

The main goal of this lunar infrastructure is to shield future bases from the dangers of rocket exhaust, including gas, dust, and small particles. The necessity of such protection was highlighted when the Apollo 12 mission brought back the Surveyor 3 probe, which had been damaged by dust from the Lunar Module Intrepid.

The need for these protective measures is further underscored by the expected impact of SpaceX’s Starship vehicle, which will be used in NASA’s Artemis 3 mission. The exhaust from these rockets could affect the lunar environment over a large area.

Future Considerations

Walther pointed out the durability of dry-stone walls, “Some dry stone walls on Earth have endured for thousands of years.” While the lunar walls will not need to last as long, the lack of weathering agents like air, water, and wind on the moon means they will primarily need to withstand rocket blasts.

Challenges include the distance the excavator must travel to gather materials and the energy required for the construction. The team estimates the excavator will need to travel between 776 and 880 kilometers. Despite these challenges, this method is significantly more energy-efficient than other construction techniques, such as heating regolith to create cast sections or using microwave heating.

Building the blast shield is estimated to take about 63 Earth days, although this could double if the excavator relies on solar power and must pause for the lunar night. Using portable recharging stations or nuclear power sources could help mitigate these delays.

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