Both the lander and the rover of the Chang'e-4 probe switched to the dormant mode for the lunar night on the far side of the moon on July 9, 2019. The scientific instruments on the Chang'e-4 probe worked well during the seventh lunar day, the China National Space Administration reported. Data collected on these instruments have been used to study the composition of the lunar mantle that exists between the crust and the core. A lunar day equals to 14 days on Earth, and a lunar night is the same length. The Chang'e-4 probe switched to dormant mode during the lunar night due to the lack of solar power.