Hong Kong Operation Robot for Chang‘E-8 Mission

The Hong Kong Operation Robot (HKOR) is currently under development led by InnoHK Hong Kong Space Robotics & Energy Centre for China’s Chang’E-8 lunar mission. Chang‘E-8 is scheduled to land in the lunar south pole region, an area of high scientific interest due to permanently shadowed regions and potential water ice. The mission’s nominal operational lifetime is two years. HKOR has a total mass of approximately 100 kg. Unlike classical planetary rovers focused primarily on mobility or simple sample acquisition, HKOR is a sophisticated, dual-arm robotic system designed to perform dexterous, human-like operations on the lunar surface. Its development addresses some major technical challenges: autonomous decision-making in unknown and poorly illuminated environments, coordinated bimanual manipulation under low gravity and abrasive dust, and high-performance operation under extreme resource constraints.

1. Mobility and Navigation System

HKOR employs a four-wheeled chassis design. Four wheels provide a balance between mechanical simplicity, mass efficiency, and redundancy. Each wheel is independently driven and steered, enabling holonomic planar motion including turn-on-the-spot capability, which is essential for manoeuvring in the rocky, steep-terrain environment of the lunar south pole. The suspension is applied to the rear wheels, providing passive adaptability to surface unevenness.

For autonomous navigation, HKOR is equipped with a sensing suite comprising at least two sets of stereo cameras: a Navigation Camera (NavCam) pair on the mast and a Hazard Camera (HazCam) pair at the robot belly level. The NavCam provides the field of view for long-range path planning and global localisation, while the HazCam offers a shorter baseline and wider angular coverage for detecting obstacles such as boulders, craters, and steep slopes within the immediate vicinity. Both camera pairs operate in the visible spectrum but are designed with high sensitivity to cope with the challenging lighting conditions at the south pole, where the Sun remains low on the horizon, creating long shadows and high-contrast scenes.

To support absolute localisation and attitude determination, HKOR is additionally equipped with a star tracker for celestial orientation and an Inertial Measurement Unit (IMU) for dead reckoning between visual updates. The star tracker provides yaw, pitch, and roll references by identifying star patterns, which is particularly valuable at the south pole where magnetic field information is unavailable. The IMU (accelerometers and gyroscopes) tracks incremental motion and orientation changes at high frequency, bridging the gaps between camera and star tracker updates. Sensor fusion combines NavCam visual odometry, star tracker absolute heading, and IMU-integrated displacement to produce a robust, drift-free pose estimate, enabling safe traversal over kilometre-scale traverses across the two-year mission.

2. Embodied Intelligence for Autonomous Operation

HKOR will demonstrate the integration of embodied intelligence into a flight-qualified system, capable of perceiving an unfamiliar lunar environment, autonomously navigating to a scientific target, and making real-time decisions.

This capability moves beyond conventional teleoperation, which suffers from a round-trip communication delay. Our robot can be pre-trained on foundational manipulation skills (grasping, plugging, unplugging, instrument deployment) using simulation-to-reality transfer learning. Once on the Moon, if HKOR encounters a target that differs from its training data, it can autonomously adapt its motion and force strategy without waiting for ground commands. For mission-critical actions, ground confirmation is retained as a safety backup. The repetitive, exploratory, and time-sensitive tasks are handled autonomously, drastically improving operational efficiency over the two-year mission.

3. Dual-Arm Coordinated Manipulation

Another key robotic innovation is dual-arm coordinated manipulation designed specifically for 1/6 g and high-dust conditions. Low gravity reduces object inertia, making samples prone to being pushed away or becoming airborne. Abrasive lunar dust can degrade mechanical joints if not properly managed.

HKOR addresses these challenges through mechanical design and advanced control. The end-effectors include rigid grippers and one flexible gripper that is also equipped with tactile sensing. Using a high-frequency control loop, the two arms operate in a master-slave or fully cooperative mode. If one arm encounters sudden resistance, the other instantly adjusts its compliance to compensate. To combat dust, HKOR employs multi-stage sealing on all moving joints and specialised vacuum-compatible solid lubricants.

4. Onboard Payload Experiments

HKOR also carries further  payload experiments that contribute to the broader scientific and technological objectives of Chang’E-8. This covers a Solar CLV (Corona and Visible) Irradiance Monitor supporting space weather monitoring and solar physics research; a Micro-Tubular Elastocaloric Solid-State Cooler, ideal for cooling infrared sensors or scientific samples under the extreme temperature swings of the lunar surface; an Impact-Resistant, Energy-Storable Carbon Fibre Reinforced Polymer (CFRP) Multifunctional Composite (a structural battery).

5. Resource-Constrained Realisation

All of the above—embodied intelligence, dual-arm coordination, and autonomous navigation—are realised under severe onboard limitations. HKOR has a total mass of 100 kg. Power is constrained to well under 150 W for all robotic functions. The flight-qualified, radiation-tolerant processor provides approximately 10 TOPS—orders of magnitude less than terrestrial robots. Despite this, our team has successfully optimised and deployed neural network models for perception, decision-making, and high-frequency force control, demonstrating that terrestrial-level robotic dexterity can be miniaturised and ruggedised for the Moon.

6. Impact on Hong Kong’s Space Technology Ecosystem

For Hong Kong, this mission serves as a critical capability builder. HKOR represents the first time a Hong Kong-led team has full system integration responsibility for a major robotic system in a national deep-space mission. The project has fostered expertise in systems engineering, environmental qualification, and mission management. Underlying technologies are already being transferred to medical robotics and nuclear inspection robots through InnoHK-supported platforms, contributing to the sustainable development of the space economy.

Conclusion

The Hong Kong Operation Robot for Chang’E-8, with its 100 kg four-wheeled chassis, visual-inertia fusion navigation, dual-arm manipulation, embodied intelligence, and integrated payload experiments, marks a significant step forward in planetary robotics achieved under real-world flight constraints. It also exemplifies how focused investment through InnoHK enables unique contributions to international space exploration.