Soft landing on the far side of the moon involves complex terrain and requires a higher level of hazard avoidance capability than landing on the near side of the moon. Restricted by propellant and other factors, the Chang’e-6 lander adopt a different method from Chang’e-4 that raises the hazard avoidance altitude to expend its hazard avoidance capability. Instead, it combines part of the “pinpoint” landing technology with hazard-avoidance. The pinpoint landing method helps the lander avoid known large-size hazards through unidirectional range control in the main braking phase. And the rough-fine-relay hazard-avoidance strategy identifies and avoids small-size hazards unknown in advance during the flight process below the approach phase to ultimately realize a safe soft landing. The hazard avoidance scheme adopted by Chang’e-6 is a technological upgrade compared with the previous Chang’e series landers, and was technologically verified in advance for the subsequent realization of a full-fledged pinpoint landing.

Aiming at constraints on the takeoff mission on the far side of the moon, Guidance navigation and control system (GNC) made a break through in the autonomous takeoff technology, raised an automatic program for soft landing and takeoff, and ultimately took off and ascended into the target orbit punctually and autonomously. The work process of GNC on the Moon is introduced. The autonomous takeoff technology is described, including autonomous celestial positioning, inertial navigation system alignment, launch direction calculation and the autonomous star sensors scheduling strategy. The automatic program for soft landing and takeoff is based on stating parameters by stages and variable length command process mechanism. Combining the autonomous takeoff technology with the automatic program for soft landing and takeoff realized the world’s first sample return from the far side of the moon efficiently and reliably in the Chang’e-6 mission.

The rendezvous and docking in the lunar orbit is one of the most critical technology of the Chang’e-6 mission. To achieve high-precision and high-reliable lunar rendezvous and docking, Chang’e-6 adopted an autonomous navigation algorithm based on filter independence and estimation fusion, and a new homing guidance algorithm based on Hohmann rendezvous with time and trigger angle planning method. Furthermore, a novel relative states controller for closing phase is designed, in which the adaptive adjustment of control parameters is realized by using dynamic programming to the dead zone, and a new jet pulse width modulation method is used, which is equivalent to the Pseudo-Rate Modulator(PRM). Based on these autonomous guidance navigation and control technology, the problem of autonomous lunar rendezvous and docking with weak ground support and strong environment uncertainty is solved, and these techniques enabled China to complete the historic Lunar Sample Return mission from the far side of the moon.

The mission of landing on the back of the moon and taking off from the surface of the moon was successfully completed by Chang’e-6  guidance, navigation and control (GNC) system for landing and ascending. The design of high reliability flight control system for Chang’e-6 GNC is systematically summarized in this paper. Compared with Chang’e-5, there are two main features. One is that all the hardware products experience a long period of storage and have failure risk. So for Chang’e-6 flight control system, the method of multi-sensor comparison is designed and the focus is to monitor the work status of all the hardware products in order to make sure that all the hardware products meet the operating requirements. The other is that Chang’e-6 firstly adopts autonomous technological process during taking off from the surface of the moon, which has great impact on the lunar sample return mission. So a method of calculating takeoff attitude based the star sensors is designed to focus on the monitoring of autonomous takeoff procedure. At last, the validity of the design is verified through the onboard data.

An autonomous momentum management strategy is proposed to solve the problems of the disturbance to the mission orbit and the influence on long life of the Queqiao-2 relay satellite, which caused by the momentum wheel unloading under the control of thrust. Firstly, a momentum predictive model based on the satellite’s attitude maneuver is established to predict the satellite’s momentum changes, avoiding the problem of momentum wheel saturation during satellite maneuvering. Secondly, an event triggering momentum management strategy is used to achieve autonomous management of the relay satellite on orbit momentum, increasing the jet unloading period effectively. In addition, the coupling jet unloading is adopted to improve the stability of obit maintenance. Finally，the experiments and flight results verify the effectiveness of the proposed momentum management strategy.

Chang’e-6 successfully completes the world’s first sampling and takeoff on the far side of the moon, opening a new chapter of lunar science. The reliability of control software plays an extremely important role in the reliable operation of the entire aircraft system. This article elaborates on the key points of software reliability design of the control system, considering the practical characteristics of the software system for the Chang’e-6 spacecraft. Describe the reliability design method of the Chang’e-6 control software from two perspectives: program reliability design and data reliability design. Apply error avoidance, error checking and fault-tolerant in software reliability design, propose a software synchronization and recovery method that combines time, data and events. Using the software reliability design described above will help improve the reliability of aerospace control software and ensure the success of space missions.

This paper comprehensively utilizes three key data sources to prepare the inputs needed for descent image navigation: Chang’e6 lander position and attitude data, high resolution lunar surface images captured by Chang’e-6’s cameras, and detailed lunar terrain information. Based on Chang’e-6’s descent imagery data, this paper uses orbital data to establish an initial landing zone model, then applies advanced computer vision techniques to register and fuse camera images with terrain information, validating the feasibility of visual navigation through orthophoto feature point matching and crater recognition matching methods. Visual navigation positioning can be fused with inertial navigation positioning data, significantly improving positioning accuracy and reliability. Research results show that visual navigation methods can effectively correct cumulative errors from inertial navigation and serve as a key component of integrated landing navigation. This navigation technology is not only applicable to the Chang’e-6 mission but can also be extended to other lunar and planetary exploration missions, providing strong technical support for future deep space exploration.

As a kind of import deep space exploration tool, the lightweight and miniature robots with low resource occupancy and dexterous maneuverability are convenient for the deployment. The robots can execute surface exploration individually and expand exploration scope or collaborate to complete exploration or operations with other robots. In this paper, an autonomous intelligent mobile robot named Jinchan, is developed to lunar surface exploration and its technologies are presented. Jinchan robot has been applied successfully in Chang’e-6 lunar exploration mission, which took successfully the full body picture of the lander and the ascender’s assembly on lunar surface by autonomous intelligent environment perception, relative navigation, planning and decision making, and realized the first application of the new Artificial Intelligent technology to the deep space exploration field. The total mass of Jinchan robot is ouly 4.5 kg, so far it is the first,lightest and smallest autonomous intelligent mobile robot rover for extraterrestrial surface exploration and photography.

In space applications, microminiaturization and low cost design is becoming an important idea and development trend. Toward deep space explorations, a microminiaturized artificial intelligence computation system architecture based on commercial off the shelf (COTS) components is presented and its design method is introduced. Further, the essential hardware and software of the artificial intelligence computation system is implemented for the microminiaturized lunar autonomous and intelligent rover, which is verified not only by various ground environmental simulation experiments, but by successful in orbit flight on the moon surface. The method and the design provide a basis for the further space application of COTS components.

The γ off sensor is an important sensor product in the application of lunar probe navigation guidance and control system. It collimates γ photons to the lunar surface and receives y photons backscattered on the lunarsurface. By counting y photons, it is used to measure the height of the probe from the lunar surface in real time during the landing of the lunar probe on the lunar surface. A series of actions such as closing the brake engine enable the lunar probe to land on the moon stably and reliably. Aiming at the differences between the calibration and application scenarios of the γ altimeter in the lunar environment and the earth environment, based on the physical model of γ photon altimeter, the static characteristics of the γ altimeter in atmospheric environment and vacuum environment were simulated and calculated. The influence of the vacuum environment on the measurement accuracy of the γ shutdown sensor was analyzed, and the lunar landing environment simulation system was constructed for verification. The comparison between the vacuum environment and atmospheric environment was obtained The effect of the count rate is less than 10%, and the height error of about 40cm will be generated near the expected shutdown height. The analysis results can be used for the calibration and conversion of the Cislunar height of the sensor products, to carry out height correction, and to guide the engineering development of the products.

The long term storage life analysis and practical work of Chang’e-6 fiber optic gyro inertial measurement unit are carried out. The factors affecting the storage life of the fiber optic gyro inertial measurement unit are identified, and a set of multi-source information fusion life analysis method based on natural storage test is proposed. The results of Chang’e-6 flight test show that the storage life analysis method and storage measures adopted are effective, and can be used as auxiliary means for subsequent storage reliability evaluation and engineering evaluation of fiber optic gyro inertial measurement device.