China's Tianwen-3 Mars Sample-Return Mission Scheduled for 2028

BEIJING, July 22, 2025 — China's ambitious Tianwen-3 mission, the country's inaugural Mars sample-return project, is on track for a launch around 2028, aiming to bring back at least 500 grams of Martian material by approximately 2031. The initiative, spearheaded by Dr. Hou Zengqian, an academician at the Chinese Academy of Sciences and the mission's chief scientist, was outlined in a comprehensive article published in *Nature Astronomy*.

Dr. Hou emphasized the mission's significance, stating, "This mission will be a critical step in China's planetary exploration. We hope to provide the international community with an unprecedented opportunity to understand Mars." The Tianwen-3 mission is structured around two launches and is expected to take seven to eight months to reach Mars. The spacecraft will operate on the Martian surface for about a year before returning to Earth, with the entire mission timeline spanning over three years.

The mission's scientific objectives are ambitious and multifaceted. Dr. Hou identified three primary goals: searching for potential signs of life, studying the evolution of Mars' habitability, and investigating the planet's geological structure and history. He stated, "The origination of life requires a habitable environment, which evolves in tandem with environmental changes. Thus, our research will connect these elements."

To achieve these objectives, nine research themes have been established, focusing on life-related elements, environmental conditions, and geological studies. The mission will utilize innovative sampling methods, including surface scooping, deep drilling, and drone-assisted collection, to ensure the diversity and scientific value of the samples. Notably, Tianwen-3 will be the first mission to conduct 2-meter-deep drilling on Mars, setting it apart from NASA's Perseverance rover, which previously collected only shallow surface samples.

Planetary protection remains a critical concern for the mission. Dr. Hou highlighted the importance of contamination control, stating, "Strict measures are required to prevent contamination of Mars by the spacecraft and protect Earth from potential Martian life." The mission will adhere to the planetary protection policies established by the Committee on Space Research, ensuring both Martian and terrestrial biospheres are safeguarded.

The selection of a landing site on Mars is pivotal, impacting the mission's scientific objectives. From an initial pool of over 80 candidate sites, the team has narrowed the list to 19, with final selections expected by the end of 2026. The chosen sites will be strategically located between 17 degrees and 30 degrees north latitude, optimizing the potential for discovering and preserving signs of life.

Moreover, the Tianwen-3 mission adopts an open and collaborative approach, inviting global scientific participation from the outset. Dr. Hou noted, “We aim to build a global platform for scientific collaboration through planetary exploration.” Key technologies for the mission are still under development, but the team is making significant strides in utilizing Martian observational data to refine landing-site selections.

Liu Jizhong, chief designer of the Tianwen-3 mission, described the sample retrieval process as one of the most technically challenging endeavors since the Apollo program. The mission involves 13 complex phases, utilizing both in-situ and remote-sensing detection technologies. The successful execution of this mission could mark a significant milestone in space exploration, enhancing our understanding of Mars and the broader universe.