WUHAN, Nov. 19 (Xinhua) -- China has inched closer toward its ambitious goal of building infrastructure on the moon, as the first set of experimental "lunar soil bricks" returned to Earth after a year-long exposure to the harsh environment of space.

The bricks, part of a pioneering experiment aboard China's space station, arrived last week on the Shenzhou-21 spacecraft. Experts confirmed that the sample unit was in good condition following initial inspections.

This signals an engineering progress in China's long-term lunar program, which includes landing astronauts on the moon by 2030 and constructing a basic model of the International Lunar Research Station by 2035.

The experiment began in November 2024, when the Tianzhou-8 cargo ship ferried the simulated lunar-soil samples up to the space station. A total of 74 small bricks were designed to be mounted on an external exposure platform on the station's exterior.

Planned as a three-year study, the project will see the return of sample batches after one, two and three years for detailed analysis, according to the team led by Ding Lieyun, a scientist at Huazhong University of Science and Technology.

By analyzing the chemical fingerprint of authentic lunar specimens brought back by China's Chang'e-5 mission, Ding's team engineered a regolith simulant and pressed it into bricks through hot-press sintering.

They opted for volcanic ash from Changbai Mountain in northeast China's Jilin Province, which closely mirrors the composition of lunar regolith.

The resulting blocks share the density of conventional bricks, yet boast more than triple their compressive strength, remaining stable across the moon's brutal temperature swings, ranging from minus 190 Degrees Celsius to 180 Degrees Celsius, and under constant cosmic radiation.

"For constructing lunar scientific facilities, utilizing locally-sourced materials from the moon is the preferred approach," Ding said.

Drawing inspiration from traditional Chinese masonry techniques featuring mortise-tenon joint structure, the team has developed a way to sinter simulated moon dust into bricks of various sizes. The sintering process is expected to be powered by concentrated solar energy on the moon.

They also developed a robotic system to handle the assembly like LEGO blocks, with the final step involving the use of 3D printing to reinforce the structure.

Next, the scientists plan to analyze the returned bricks to understand how the space environment has altered their structure and properties.

This data is vital for creating accurate models to predict the long-term durability and behavior of such materials in the actual lunar environment, providing the scientific foundation for future extraterrestrial construction.