In support of the Nation’s first lunar sample return mission, a research team at The Hong Kong Polytechnic University (PolyU) developed and manufactured one of the key systems for this historic undertaking, namely the “Surface Sampling and Packing System”, in collaboration with the China Academy of Space Technology.
The PolyU-developed system accomplished the tasks of automatic sample collection and packaging on the lunar surface following the soft landing of the Chang’e 5 probe on 1 December 2020. The vehicle carrying the samples is currently on course back to Earth and is expected to touch down in China’s Inner Mongolia region this week.
Chang’e-5 is the world’s first lunar-sample return mission in more than 40 years, aiming to bring back a large number of lunar samples of up to two kilograms via robotic means. The probe adopts two methods of moon surface sampling: one uses a robotic arm for multiple-point surface sample collections, and the other is to drill underground.
The team led by Professor YUNG Kai-leung, Sir Sze-yuen Chung Professor in Precision Engineering, Chair Professor of Precision Engineering and Associate Head of Department of Industrial and Systems Engineering, PolyU, was tasked in 2011 to develop the “Surface Sampling and Packing System”, a comprehensive system for lunar surface sampling, packaging and sealing.
The Secretary for Innovation and Technology of the HKSAR Government stated in the Chang’e 5 lunar exploration project, PolyU fully demonstrated its rich experience accumulated in national and international space projects, its cutting-edge technology as well as its innovative thinking. PolyU’s efforts in research are in line with and complementary to the Government’s goal of developing Hong Kong into an international innovation and technology hub.
The PolyU President noted that the PolyU researchers developed the impressive pioneering ‘Surface Sampling and Packing System’ to facilitate the success of this milestone mission. By contributing to such a sophisticated national space project, the University has demonstrated its substantial research competence and commitment to producing breakthrough solutions that push forward the frontiers of technology and science.
Consisting of two samplers for collecting loose and sticky forms of lunar regolith, two near-field cameras, as well as a packaging and sealing system, the “Surface Sampling and Packing System” has more than 400 components constructed in different materials including titanium alloy, aluminium alloy and stainless steel, which make the instruments light in weight but at the same time durable and strong enough to withstand the harsh space environment.
The system needed to operate on the sun-facing side of the Moon where the ground temperatures could be as high as 110 degree Celsius, this innovation had to be highly sophisticated and capable of functioning under extremely high temperatures.
It also needed to withstand the extreme space environment during travel to and landing on the Moon which meant enduring impact and shock during lift-offs and landings, high vacuum on the moon, exposure to solar wind and cosmic rays, as well as high-speed re-entry to Earth’s atmosphere.
To meet the limited payload requirement, the team had to be innovative in its mechanism design and be stringent in weight control. For example, the two samplers are more than a tool to acquire lunar regolith. They are also used to pick up and move the sample container from the lander to the ascender atop.
Features of the Surface Sampling and Packing System:
- Sampler A – Around 35 cm in length, Sampler A, in the shape of a shovel, is specifically engineered for collecting loose regolith. The vibration and impact during the closing of the sampler is an elaborate design to dislodge excessive debris, chisel away large pieces of regolith, tightly enclose the samples and precisely deposit the selected samples into the container without contaminating the surrounding.
- Sampler B – Around 30 cm in length, Sampler B is used for collecting sticky samples by coring into the ground with teeth-like metal flaps when opened. It captures the targeted samples through the closing of these metal flaps. The piston inside the sampler pushes the sticky samples into the container during the depositing of the sample when the flaps gradually open.
- Near-field Cameras– Heat resistant up to 130 degree Celsius, a near-field camera is attached to each sampler. This camera provides a monitoring and vision guidance function to help select scientifically valuable lunar samples. The vision guidance function also enables the sampler to deposit the samples into the container, grip the container and transfer it into the ascender precisely.
- Sealing and Packaging System– Weighing 1.5 kilograms, of which the sample container weighs only 360 grams and is used to seal and store the lunar samples for return to Earth, this system includes the deployment of a funnel to protect the sample container from contamination when the lunar regolith is deposited and a sweeping action to brush away excessive sample to ensure the container lid can be closed properly.
