Chinese astronauts train in caves to live & work on Moon

China's first underground cave training program, under which 28 astronauts were sent into a natural cave to train to work on the Moon, has been completed. The average temperature in the cave hovered at 8°C, and humidity reached 99%. Inside, the astronauts conducted research, logistics management, life-support operations and squeezed through ultra-narrow passages, pushing their physical limits.