China’s Chang’e 6 lunar probe mission is bound for the far side of the Moon, and there seems to be a small rover affixed to the side of the lander, as seen in new images released by the China Academy of Space Technology (CAST).

China’s National Space Administration announced today that the probe, which launched last week, has successfully entered the Moon’s orbit, a big step toward landing the spacecraft early next month.

But as Space.com reports, people have noticed that CAST’s published images show a mysterious mini rover — one that seems too small for a long-term mission. The Shanghai Institute of Ceramics hints on its website there might be an infrared imaging spectrometer on board that could be used to detect water in soil and rocks, as explained by SpaceNews.

China disclosed little on the Chang’e 6’s objectives. It’s known where it will land and that there’s a goal to bring back samples to Earth — similar to China’s collection of nearside samples on the Chang’e 5 mission in 2020. It’s also carrying payloads from France, Sweden, and Italy, as well as a Pakistani CubeSat.

This isn’t the first time China sent a surprise device to space. During China’s Tianwen-1 mission to Mars in 2021, the CNSA shadow dropped a camera that took a selfie of the Zhurong rover.