The moon is a dusty place, and in an effort to make it a little tidier, ESA is experimenting with high-energy lasers and simulated lunar soil to explore the possibility of sintered lunar debris to pave roads and landing sites for future lunar outposts and prevent the entry of damaging dust.
Even before the first robotic landings, lunar dust has been a concern for space engineers. At one time, so little was known about the lunar surface that there was concern that craters and even entire lunar maria could be filled with extremely fine dust that would swallow spacecraft like cosmic quicksand.
Fortunately, this proved not to be the case, but what the first explorers found was almost as bad. The lunar dust encountered by the Apollo astronauts and robotic probes like Surveyor and the Soviet Union's Lunar Hodder became so viscous due to the complete lack of water washout and lots of static electricity that it coated everything.
To make matters worse, dust is composed of very sharp abrasive particles that will wear down machines and spacesuits in a short time. At the same time, dust is also a strong thermal insulator. The rover used by Apollo 17 almost crashed due to overheating, and the radiator of Lunar Rover 2 was also covered in dust and destroyed.
For these reasons and others, the cliche scenario of a lunar base sitting quietly on lunar soil is exactly what engineers want to avoid. The obvious answer is to pave roads and work areas with asphalt, just like we do here on Earth. Since asphalt is difficult to find on the moon, ESA scientists, led by Germany's BAM Institute for Materials Research and Testing, turned to lasers.
This concept is not new. In 1933, Will W. Beach proposed using giant lenses to concentrate sunlight and melt sand to build roads. The ESA team hopes to use a similar approach on the moon, using Fresnel lenses several meters wide to focus sunlight on the moon. But to make their experiment simple and feasible, a 12-kilowatt carbon dioxide laser replaced the sun and lens as part of the PAVER project.
Using simulated lunar dust, the PAVER team did more than turn tiny specks of dust into molten glass. Instead, laser beams with a diameter of 4.5 centimeters (2 inches) are used to create different geometric shapes about 20 centimeters (8 inches) in diameter, which can be locked together like tiles to form large surfaces such as roads and landing pads.
The material is glassy and brittle and can crack when compressed, but it can be repaired in place and made stronger by melting larger areas and layering them. It is expected that eventually structures like the 100-square-meter (1,076-square-foot) landing pad, which consists of dense layers 2 centimeters (1 inch) thick, can be built in about 115 days.
Additionally, the PAVER method could be used to create general building materials for other structures on the lunar outpost.
The research was published in Nature Scientific Reports.