Tianwen-3

Tianwen-3 is a robotic mission under development by the China National Space Administration (CNSA) to bring samples of Martian rock and soil back to Earth. It is currently planned for launch in 2028, with a return to Earth expected by 2031. The primary objective is to search for signs of past or present life on Mars.

The mission uses two spacecraft: an orbiter combined with an Earth-return vehicle, and a lander paired with an ascent vehicle. This design is similar to China’s lunar sample-return missions, Chang’e 5 and Chang’e 6, but unlike those, Tianwen-3 will require two separate launches to Mars. Each spacecraft will be carried by a Long March 5 rocket from the Wenchang Space Launch Site, targeting the December 2028–January 2029 Mars launch window. If successful, it would be the first mission ever to return samples from Mars; the status of the competing NASA-ESA Mars Sample Return mission remains uncertain. The mission includes planetary protection measures to prevent contamination of Mars by Earth organisms. Early plans also mentioned a helicopter and a crawling robot, but these have not been confirmed.

Tianwen-3 is China’s third Mars mission, following the failed Yinghuo-1 orbiter (2011) and the successful Tianwen-1 orbiter, lander, and rover (2020–present). It is also the third mission in China’s Planetary Exploration of China program, after Tianwen-2, which targets an asteroid and a comet.

In summer 2022, at a deep space exploration forum at Nanjing University, Sun Zezhou—chief designer of Tianwen-1—detailed the two-launch architecture. The current plan calls for two Long March 5 launches around 2028. One will send the orbiter/return-vehicle; the other will send the lander/ascent-vehicle.

After landing, the lander will collect surface samples using a drill and possibly an autonomous multi-legged mobile robot. After several months on the surface, once samples from both the lander and the robot are stored, the ascent vehicle will launch from the lander and rendezvous with the waiting orbiter. The samples will be transferred to the orbiter/return-vehicle, which will then depart for Earth, returning via an atmospheric reentry vehicle.

The mission’s main goal is to search for biosignatures. In 2024, scientists identified 51 potential landing sites that meet current engineering constraints (altitude below −3 km, latitude between 17°N and 30°N, slope less than 8°, and rock abundance below 10%). These sites include one in Amazonis Planitia, twelve in Utopia Planitia, and 38 in Chryse Planitia or Arabia Terra.

On 11 March 2025, CNSA opened Tianwen-3 to international partners. Teams may propose piggyback payloads or independent scientific instruments for inclusion. The Earth-return spacecraft has 15 kilograms of mass allocated for international payloads, and the Mars orbiter has another 5 kilograms. Proposals are due by 30 June 2025, with final selection expected in October 2025. Selected flight hardware must be delivered in 2027.