Recently, Prof. Ding Xilun’s group from the School of Mechanical Engineering and Automation published a correspondence article titled “China’s ambitions and challenges for asteroid–comet exploration” in Nature Astronomy, a well-known international online journal in the field of astronomy, astrophysics and planetary science.

Prof. Ding Xilun is the corresponding author, and the two co-first authors are Zhang Tao, a Ph.D graduate of Beihang University, class of 2017 (now an associate professor at Guangdong University of Technology and a visiting scientist at Max Planck Institute for Intelligent Systems, Germany) and Xu Kun, an associate professor at the School of Mechanical Engineering and Automation, Beihang University.

Small celestial bodies (SCBs) contain abundant pristine information about the early Solar System, providing a unique window into its origin and evolution. During the past three decades, nearly twenty probes explored SCBs with great success, including the European Rosetta mission, the Japanese Hayabusa 1 and 2 missions, and the NASA's OSIRIS-REx mission to sample regolith for return or in situ analysis. In recent years, China has achieved remarkable progress in space exploration, as illustrated by the Chang’e and Tianwen-1 missions. China is now actively pursuing an ambitious plan to explored SCBs.

The article introduces the planning of China’s SCBs exploration mission. The multistage and multitask mission is planned to visit two remote objects. The first target is planned to be a sample return mission to a near-earth asteroid 2016 HO3. The second target is to fly around and detect the main-belt comet 311P/PANSTARRS. The article further introduces the scientific goals, engineering objectives and the mission payload. Through the implementation of the mission, it is expected to make a breakthrough in the core technologies in the field of space exploration so that China’s SCBs exploration is able to reach an internationally advanced level, while greatly promoting the development of planetary science in China.

Extracting sample from the surface soil is extremely difficult on rubble-piled and irregular-shaped SCBs which have zero gravity, high vacuum and low temperature. There are two typical approaches to sample SCBs, namely anchor-and-attach architecture and touch-and-go architecture. The former requires a complex thrusting and anchoring system, which is extremely sensitive to the properties of the surface regolith but allows for long-time operations and thus more controlled sampling. The latter option eliminates any need to land and anchor because surface sampling is completed through a short-time interaction, resulting, however, in more complicated navigation, guidance and control.

There is still no successful precedent for the anchor-and-attach architecture. The planned Chinese mission will use both architectures to guarantee that at least one works. At present, there are relevant researches on both architectures including the regolith-sampling robots which are instrumental in acquiring regolith samples for return or in situ analysis in deep-space exploration developed by Professor Ding Xilun’s group and China Academy of Space Technology.

This project is still extremely challenging for China. To succeed, a series of critical technologies will need to be mastered. These include remote and long-time interplanetary cruises with high-efficiency, long-life propulsion engines and high-precision navigation, guidance and control during orbit transfer at well-designed manoeuvring points. For the sample acquisition, fully autonomous descent-anchoring-and-sampling, anchoring and attaching mechanism with broad terrain adaptability have to be developed. Finally, adaptive thermal control in extreme interplanetary environments, and new terrestrial verifying methods and test rigs are also required.

Prof. Ding Xilun’s group has been engaged in the research on space mechanisms and robotics and has published a series of research results in the areas of mechanical design of recon-figurable planetary rover, motion control, simulation analysis and so on. The group also participated in the Chang’e 5 mission.

The link to the article:

https://www.nature.com/articles/s41550-021-01418-9

Reported by Liang Yongjian

Reviewed by Zhang Zhigang

Edited by Jia Aiping

Translated by Li Zhuoyang