Wall-building robot eyed for blast shield construction on the Moon

When you live on the Moon, your only option for commuting back to Earth or onward to Mars will be some kind of rocket. But each launch will kick up a hellstorm of debris. Building walls to contain all that mess might one day fall to autonomous rovers.

During the Apollo 12 mission in 1969, astronauts brought back parts from the Surveyor III lander which had been dropped to the lunar surface in early 1967. When those pieces were examined it brought to light an issue with lunar comings and goings – the rockets that carry people and cargo to and from the surface kick up a lot of regolith, which had actually damaged the lander. In fact, it’s estimated that Moon landings can affect the lunar environment thousands of meters away from the actual landing site.

NASA’s Artemis mission is set to establish a colony on the Moon and will use SpaceX’s Starship Human Landing System (HLS) to ferry colonists between an orbiting gateway and the lunar surface. That means a lot of dust is set to get kicked up in the coming years, and containing it to protect habitats and other sensitive equipment is going to be a key piece of the Moon-life puzzle.

The idea of building walls around launch and landing sites has been explored before with possible solutions including the microwave heating of surface soil to create Moon bricks and the use of 3D printing to create structures from pastes made from lunar soil. But according to a new study led by Jonas Walther, there’s a cheaper, better way to make blast shields that doesn’t involve transforming lunar materials into something else. Walther has done work at ETH Zürich’s Institute of Robotics and Intelligent Systems and at the Center for Space and Habitability in Bern. He now works at Switzerland’s Venturi lab which studies designs for lunar rovers.

Walther and his colleagues propose simply stacking up the boulders from the lunar surface to make stone walls that could contain blast debris. He says such a project could be easily carried out by autonomous rovers, such as the HEAP excavators demonstrated by ETH Zurich last year, which you can see in action in the following video.

Walther’s team says such an approach would be two orders of magnitude more energy efficient than previously proposed ideas. That’s because simply using existing boulders doesn’t require the transport of any materials – other than the rovers – to the lunar surface. Nor does it require the heating or transformation of lunar soils into building materials.

The researchers examined the possibility of building their boulder blast shields in two areas on the Moon: the Aristarchus Plateau and the Shackelton-Henson Connecting Ridge. Their calculations focused on building shield rings that would have a radius of 50 meters (164 ft), a circumference of 314 m (1,030 ft) and a height of 3.3 m (10.8 ft). In both areas, the rovers would have to travel up to 1,000 km (621 miles) to harvest boulders. With all of those factors accounted for, and allowing time for the rovers to charge and hibernate during the lunar night, the team figures the shield wall could get built in a minimum of about 126 Earth days.

The team acknowledges that one of the challenges of the proposed method is that stacking the boulders will lead to small gaps between them which could let regolith escape. So these gaps would need to be sealed using smaller stones, regolith or other materials. Still, the researchers feel the plan is worth considering as part of the suite of construction methods that will no doubt be used on the Moon, especially because of the potential energy savings it affords.

The research has been published in the journal Frontiers in Space Technology.

Source: Frontiers in Space Technology