When you live on the Moon, your only option for getting back to Earth or going to Mars would be some kind of rocket. But each launch would create an inferno of debris. Building walls to contain all that mess may one day fall into the hands of autonomous rovers.
During the Apollo 12 mission in 1969, astronauts recovered debris from the Surveyor III lander, which had been dropped onto the lunar surface in early 1967. When these debris were examined, a problem with the lunar ups and downs was revealed: the rockets that carried humans and cargo to and from the surface threw up large amounts of regolith that damaged the lander. In fact, it has been estimated that lunar landings could have affected the lunar environment thousands of meters away from the actual landing site.
NASA’s Artemis mission is preparing to establish a colony on the Moon, and will use SpaceX’s Starship Human Landing System (HLS) to ferry colonists between an orbiting gate and the lunar surface. That means a lot of dust will be kicked up in the coming years, and controlling it to protect habitats and other sensitive equipment will be a key piece of the lunar habitat puzzle.
The idea of building walls around launch and landing sites has been explored before, with possible solutions including heating surface soil in microwaves to create moon bricks and using 3D printing to create structures from lunar soil paste. But according to a new study led by Jonas Walther, there is a cheaper and better way to make blast shields that doesn’t involve converting lunar materials into something else. Walther has done work at ETH Zürich’s Institute for Robotics and Intelligent Systems and the Center for Space and Habitability in Bern. He currently works at Switzerland’s Venturi lab, which is studying designs for lunar rovers.
Walther and his colleagues propose stacking rocks on the lunar surface to make rock walls that could trap blast debris, a project they say could easily be accomplished by autonomous rovers, such as the HEAP excavators demonstrated by ETH Zurich last year, which you can see in action in the video below.
Autonomous excavator builds six-metre-high dry stone wall
Walther’s team says such an approach would be twice as energy efficient as previously proposed ideas. That’s because using only existing rocks wouldn’t require transporting any materials (aside from the rovers) to the lunar surface, and it wouldn’t require heating the lunar soil or converting it into building materials.
The researchers examined the possibility of building rockburst shields at two sites on the Moon: the Aristarchus Plateau and the Shackelton-Henson Connection Ridge. Their calculations focused on building shield rings with 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). At both sites, rovers would have to travel up to 1,000 km (621 mi) to collect rock. Taking all of these factors into account, and allowing the rovers time to recharge and go to sleep during the lunar night, the team calculates that the shield wall could be built in at least about 126 Earth days.
The team acknowledges that one of the challenges of their proposed method is that stacking rocks can create small gaps between them, which can allow regolith to escape. These gaps would therefore need to be filled using smaller rocks, regolith or other materials. Still, the researchers believe the scheme is worth considering as part of a suite of construction methods that will undoubtedly be used on the Moon, particularly because of the potential energy savings it could offer.
The research was published in the journal Frontiers in Space Technology.
Source: Frontiers in Space Technology