China has moved closer to building infrastructure on the moon as the first batch of experimental “lunar soil bricks” returned to Earth after a year-long exposure on the exterior of China’s space station. The samples were brought back by Shenzhou-21 last week alongside three astronauts.

Researchers confirmed the bricks remained intact with no damage from space debris, marking a key step in China’s lunar program, which aims to land astronauts by 2030 and build the basic structure of the International Lunar Research Station by 2035.

The 34 blocks, each about 100 grams, were made of simulated lunar soil using hot pressing and microwave sintering, giving them a strength three times greater than ordinary bricks. Some bricks included pre-cut seams to study how a year in space affects mechanical properties. The experiment also examines thermal behavior and radiation resistance, supported by a ground control group.

The study began when Tianzhou-8 delivered 74 small bricks to the Tiangong station. Over its planned three-year cycle, one batch will return each year, allowing scientists to model how such materials may perform after 5, 10, or 20 years on the lunar surface.

China plans to rely on in-situ lunar resources to build its base, and scientists are exploring interlocking “mortise-tenon” brick designs for future construction. “These bricks may eventually help build China’s lunar base — the ‘Guanghan Palace,’” said researcher Zhou Yan.