China has set its sights on one of space exploration’s most complex and high-stakes missions yet: returning samples from the Martian surface. Tianwen 3, the nation’s first Mars sample-return mission, is slated for launch around 2028 and aims to bring at least 500 grams of Martian material back to Earth by 2031.
China’s first Mars rover, Zhurong, with its Tianwen-1 landing platform, which touched down on the Red Planet in May 2021. The mission’s success aided China’s development of the more ambitious Tianwen-3, which is a Mars-bound sample-return mission slated to launch in 2028. Credit: Xinhua
Details of the mission were published for the first time in Nature Astronomy by Hou Zengqian, chief scientist for Tianwen 3 and academician of the Chinese Academy of Sciences. The paper outlines both the mission architecture and its ambitious scientific goals, which include the search for signs of ancient Martian life.
“This mission is a critical step in China's planetary exploration roadmap,” Hou said. “We hope it will offer the international community a new lens through which to understand Mars.”
Tianwen 3 will involve two separate launches and a round-trip journey of more than three years. The spacecraft will take approximately 7–8 months to reach Mars, operate there for about one Earth year, and then begin its return to Earth.
The primary scientific objectives are bold and far-reaching:
- Search for signs of life: including biomarkers, fossils, and possible microbial life forms such as archaea.
- Understand past habitability: by investigating Mars’ water history, atmospheric evolution, and ancient oceans.
- Decode geological history: including surface features, internal structures, and planetary dynamics.
Hou emphasized that these three goals are deeply interconnected. “Life arises in habitable environments, and habitability itself is shaped by geological processes,” he explained.
Nine specialized research teams have been formed to tackle these objectives, covering disciplines such as planetary geology, geochemistry, and astrobiology.
Unlike NASA’s Perseverance rover, which collects samples for later retrieval, Tianwen 3 aims to collect and return samples in a single mission. It will use three sampling methods: surface scooping, deep drilling, and drone-assisted collection.
Notably, the mission will be the first globally to drill as deep as two meters into the Martian surface for sample extraction—an effort expected to improve the chances of finding well-preserved biosignatures.
Instead of a traditional Mars rover, Tianwen 3 will deploy a drone capable of collecting samples within several hundred meters of the lander, a maneuver aimed at enhancing the scientific diversity of the returned samples.
Tianwen 3 is being developed with strict planetary protection protocols. “Contamination control is crucial,” Hou stressed, both to protect Mars from Earth-based microbes and to shield Earth’s biosphere from potential Martian organisms.
A state-of-the-art Mars Sample Laboratory is also in the works. The facility will feature ultra-clean environments, biosafety barriers, and procedures for sterilizing and analyzing samples upon their return.
Mission success will hinge in part on choosing the right landing site. From an initial list of over 80 potential sites, 19 have been shortlisted. By the end of 2026, China will narrow this list to three final candidates.
The selected site must fall between 17° and 30° north latitude due to engineering constraints, but also offer high scientific value—particularly in the search for preserved signs of past life.
“Finding life on Mars requires a combination of favorable conditions: liquid water, a protective atmosphere, appropriate temperatures, a magnetic field, and geologic stability,” Hou said. “The right site must reflect all these factors.”
Open Doors for Global Collaboration
In a major departure from earlier mission models, China is adopting a fully open and collaborative approach to Tianwen 3. From scientific planning and instrument design to sample access, international cooperation will be central.
“We intend to build a global platform for planetary science,” Hou said. China has already hosted international conferences, invited global experts to participate in defining mission goals, and opened payload proposals to researchers worldwide. Once samples are safely returned, they will be made available to international scientists for study.
Some of the mission's technologies are still under development. Meanwhile, the team is using existing Martian data to refine the landing site and fast-track the full-chain research necessary to detect life.
Tianwen 3 places China among the leading nations in the modern space race, particularly as NASA’s Mars Sample Return program faces uncertainty. While NASA relies on a multi-phase effort with future missions required to bring Perseverance’s samples home, China is taking a more integrated approach—aiming to complete the sample and return process with one mission.
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