China is aiming to bring 500 grams of Mars back to Earth by 2031, and NASA currently has no clear plan or the funding to match it.

The CNSA (China National Space Administration) mission, called Tianwen-3, is set to launch around 2028 on two Long March 5 heavy-lift rockets (the workhorse that has already delivered both of China's Chang'e lunar sample returns) out of the Wenchang Space Launch Site in Hainan, China's southernmost province.

The launch date is deliberate, as everything depends on orbital mechanics. Mars launch windows only open every 26 months, and the one Tianwen-3 is targeting runs from December 2028 into January 2029 with little room for slippage if 2031 is the goal.

Five pieces make up the spacecraft: a lander, an ascender, a service capsule, an orbiter, and an Earth reentry module.

Finding life is the stated priority. Hou Zengqian, the mission's chief scientist, told the state-run news outlet Xinhua that the samples will be searched for microbial traces resembling early life on Earth, while leaving room for the possibility of something stranger.

He made the same point on the sidelines of the International Deep Space Exploration Conference, the annual Hefei gathering by China's Deep Space Exploration Laboratory (aka Tiandu Laboratory) that drew participants from more than 40 countries this year.

Even a null result would be worth the trip, in his view. "Regardless of whether signs of life are found, the returned Martian samples will have irreplaceable scientific value," Hou said, pointing to what microscopic, molecular, and isotopic analysis could reveal about the planet's geology and whether it was ever habitable.

The hardware has reached prototype development. Hou told state broadcaster CCTV that work is progressing and that teams across the country are pushing on the technical problems.

The landing site is another thing that needs consideration. China expects to settle that by the end of 2026, with researchers building a next-generation geological map of the entire planet in the meantime. Candidates are being weighed on geological age, evidence of past water, habitability, and how well a site might preserve biosignatures.

Then there's the matter of bringing Mars material home, which introduces a very different kind of problem: containment. The mission plans to build a planetary protection laboratory in the first phase of Hefei's Deep-Space Science City, the under-construction flagship campus of the Tiandu Laboratory, handling sterilization, unsealing, processing, and biological risk assessment.

Per scientists, the plan moving forward is for the lab to follow protocols set up by COSPAR (Committee on Space Research), the international scientific body whose planetary protection rules are the standard for spacefaring nations. The protocols run in both directions, keeping Earth microbes off Mars and keeping whatever comes back contained.

Sources: Xinhua, CGTN, National Library of Medicine, CCTV+, The Planetary Society, Space, NASA

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