China's Tianwen-3 Mars Sample Return Mission Gains HKU Expertise

Hong Kong—In a significant advancement for planetary science, the China National Space Agency (CNSA) has integrated a team of astrobiologists from Hong Kong University (HKU) into its Tianwen-3 Mars sample return mission. This mission, anticipated to launch in 2028, aims to be the first to successfully return samples from the Martian surface to Earth, potentially uncovering vital clues about the planet's capacity to host life.

Led by Professor Yiliang Li from HKU's Department of Earth Sciences, the scientific team is tasked with selecting an optimal landing site for the mission. This site will be critical for identifying regions where liquid water once flowed, thus increasing the likelihood of preserving evidence of past or even present microbial life.

The Tianwen-3 mission, consisting of both a lander and an orbiter, is poised to follow in the footsteps of several successful missions currently exploring Mars, including NASA's Perseverance and Curiosity rovers, as well as the UAE's Hope orbiter. Each of these missions is part of a broader effort to understand Mars’s geological history and its potential for life, a quest that has spanned over half a century since the Viking missions in the 1970s.

In their recent publication in *Nature Astronomy*, Professor Li and his colleagues outlined the mission's objectives, emphasizing the importance of meticulous site selection. The team is leveraging insights from both terrestrial and Martian research to identify areas rich in hydrated minerals that may have preserved microbial activity for billions of years, akin to conditions that were favorable for life on early Earth.

According to Dr. Alice Chen, an astrobiologist at the University of Science and Technology of China, “The selection of a landing site rich in geological features that indicate past water activity is imperative for maximizing our chances of finding biosignatures.”

The Tianwen-3 mission will utilize advanced technologies, including a robotic arm and a drone for sample collection, aiming to drill up to two meters below the Martian surface. This depth is crucial as it protects organic materials from harsh radiation and potential contamination from perchlorates.

Furthermore, Professor Li’s team has proposed the establishment of a Mars Sample Laboratory near Hefei, which would be equipped to analyze the Martian samples while conforming to the Committee on Space Research (COSPAR) Planetary Protection Policy. This laboratory will ensure that any potential biological agents found within the samples are contained and studied under strict safety protocols.

China’s ambitions in space exploration have gained momentum following the successful deployment of the Zhurong rover in 2021, which made China the first nation to achieve orbit, landing, and rover deployment in a single mission. The Tianwen-3 mission, therefore, represents not only a continuation of this legacy but also an opportunity for international collaboration, as the CNSA has opened an Announcement of Opportunities for global partnerships.

Looking forward, if the mission proceeds according to schedule, the samples are expected to return to Earth by 2031, marking a historic milestone in planetary exploration and potentially reshaping our understanding of life in the universe. The final selection of international collaborators is anticipated in October 2025, with flight models for selected payloads due for delivery by 2027.

As the world watches, the collaboration between HKU and CNSA could yield groundbreaking discoveries that bridge the scientific inquiry into our own planet's history with the mysteries of Mars, possibly answering age-old questions about the existence of life beyond Earth.