On December 17, 2020, the chang’e-5 mission orbiter and the orbiter were separated at a distance of 5000 km from the earth. The orbiter returned to the earth with lunar samples, and the orbiter successfully performed evasive maneuver. After the completion of the main mission, the orbiter launched an expansion mission and set off to the sun earth Lagrange L1 point, which is about 1.5 million kilometers away from the earth. < / P > < p > due to the high precision of chang’e-5 mission, the orbiter reduces many orbit corrections and saves propellant consumption. Previously, the detector system and related systems considered that they have the conditions to carry out the expansion task according to the propellant residual amount of the orbiter, the measurement and control conditions, the status of the equipment on board and the status of the uplink and downlink data transmission. After the research, it is decided that after completing the main mission, the orbiter will fly to the L1 point of the sun and earth, carry out the circling flight and carry out the detection test. < / P > < p > Lagrange point refers to the point that can make small objects stable under the action of gravity of two large objects, and the small objects basically remain static relative to the two large objects. The sun earth L1 point, located between the sun and the earth, is the best place to place the sun observation station. There, spacecraft will never be blocked by the earth or the moon, and can continuously observe the sun or the sun facing side of the earth. < p > < p > in 2011, Chang’e-2 launched an expansion mission from the lunar orbit after completing the established mission. On August 25, 2011, Chang’e-2 successfully circled another equilibrium point of solar terrestrial gravity, the solar terrestrial Lagrange L2 point. Continue Readinggather and watch! Huawei P40 Pro evaluation: excellent mobile phone photography elegant design, do you like it?