China’s robotic Chang’e-4 spacecraft did something last year that had never been done before: It landed on the moon’s far side, and Yutu-2, a small rover it was carrying, began trundling through a crater there. One of the rover’s instruments, a ground-penetrating radar, is now revealing what lies beneath.

In a paper published Wednesday in the journal Science Advances, a team of Chinese and Italian researchers showed that the top layer of the lunar soil on that part of the moon is considerably thicker than some expected — about 130 feet of what scientists call regolith.

“It’s a fine, dusty, sandy environment,” said Elena Pettinelli, a professor of mathematics and physics at Rome Tre University who was one of the authors of the paper.

Based on what NASA astronauts observed during the Apollo moon landings, other scientists said they would have expected one-quarter as much soil.