Abstract: The Sun-Earth L1 point is an optimal location for the Sun observation and is significant for the future Sun observation missions of China. Therefore, the first domestic exploration mission on the Sun-Earth L1 point was designed and implemented during the extended phase of the Chang’E-5 mission. By this flight, the design of the orbit transferring and orbiting around the Sun-Earth L1 point was verified, and the flight environments of the Sun-Earth L1 point such as the TT&C environment, the solar irradiance environment, the three-body dynamics environment and the space radiation environment were detected and verified. The results of orbit flight and environment detection were consistent with the predicted results of the design model and therefore the correctness of the design model was verified with onorbit flight data. Technological achievements, which were important references for the design of deep-space exploration missions and devices in the future, were acquired as expected and further enriched the outcome of the Chang’E-5 mission.

Key words: Sun-Earth L1 point exploration, flight test, mission design, result analysis, technological achievement