Vision based Chang’E-4 landing point localization

On December 8, 2018, China launched the Chang’E-4 lunar probe and implemented soft landing and patrol exploration on the lunar farside for the first time. Fast and high-precision positioning of the landing point is a critical step of the mission, and also an important prerequisite for surface operations of the lander and rover. Based on the high-precision image matching and geometric transformation methods, and considering the engineering requirements, the landing point location of the Chang’E-4 lander was initially determined using the near real-time high compression ratio descent sequence images. Then, the position was refined using the replayed low compression ratio descent images, and the landing point position was calculated to be (177.5884°E, 45.4565°S). The landing point localization method and result have been successfully applied to actual engineering tasks for the first time in China, thus providing important support to the topographic analysis of the landing area and mission planning of the follow-up teleoperations.