Tianwen-3 — Mars sample return bid
China's Tianwen-3 is a round-trip mission to bring Martian soil and rock to Earth. Launch is targeted for late 2028 and the samples' return for around 2031; success would make it the first Mars sample return.
The story
Tianwen-3 is China's planned mission to return samples from Mars. The goal is to collect soil and rock from the Martian surface and bring them to Earth. So far the only pieces of Mars in human hands are meteorites that were blasted off Mars and happened to land on Earth. If Tianwen-3 succeeds, scientists will for the first time study material chosen and collected on Mars itself.
The mission is split into two packages. One is a lander paired with an ascent vehicle: it touches down, gathers samples and then lifts off again. The other is an orbiter paired with a return craft: it waits in orbit around Mars, receives the samples and carries them home. The two packages will be launched separately on two Long March 5 rockets, in a launch window planned between December 2028 and January 2029.
The hardest step is not the landing or the lift-off but the meeting in between. The ascent vehicle rising from Mars has to find the return craft circling the planet and hand over the sample container. Spacecraft have met up like this without crews around Earth and around the Moon, but never yet in orbit around another planet.
Samples are to be collected with a drill on the lander, and a small walking robot that could gather material nearby is also being considered. The landing site has not yet been chosen; scientists have narrowed the options to about 50 candidate sites that meet the engineering limits. The orbit view shows the path leaving Earth and meeting Mars months later.
Mission goals
The reason to bring samples home is the difference in equipment. Instruments on a rover are limited in size and power. In laboratories on Earth, large instruments can examine the same sample in many ways, again and again, over decades. When better methods appear in the future, stored samples can be taken out and studied once more.
Dating rocks is an especially important example. Until now the ages of Martian surfaces have been estimated by counting how many craters they have. But that method is calibrated with samples brought back from the Moon, so using it on Mars leaves large uncertainties. Measuring the age of Martian rock directly from its radioactive elements would allow the whole timeline of Mars's history to be corrected.
Real samples are also needed to judge any sign of life. To tell whether an organic molecule truly came from Mars or is contamination from Earth, several laboratories must test it separately and compare results. That is why keeping the samples free of Earth material, and keeping Martian material from escaping on Earth, are treated as core requirements of the mission.
Mission chronology and background
China has built up the needed skills step by step. In 2021 Tianwen-1 entered Mars orbit, landed and drove a rover, all on its first attempt. At the Moon, Chang'e 5 (2020) and Chang'e 6 (2024) collected samples, met up with another spacecraft in lunar orbit to hand them over, and brought them to Earth. Tianwen-3 is an attempt to combine those two lines of experience in one mission.
The United States and Europe have long worked toward the same goal. NASA's Perseverance rover has already collected and sealed samples on Mars. But the follow-up mission meant to bring them home has grown so expensive that its plans have been thrown into doubt, and when it might fly is uncertain. So which country will be first to put Martian samples in an Earth laboratory is still an open question.
In March 2025 China opened the mission to international partners, offering 15 kg of space for foreign equipment on the part that returns to Earth and 5 kg on the orbiter. The schedule may still change. Chances to leave for Mars come only about every two years, so any slip quickly turns into a delay of more than two years.
Other milestones of this mission
Where to see it — sky and simulator
The launch is something to watch on a broadcast. Launches of China's large rockets are usually shown live by state media. Until the date and time are fixed, though, there is no broadcast schedule, and it is worth remembering that this mission needs two launches. The orbit view shows both packages travelling the same road to Mars and the return craft bringing the samples back to Earth over several years.
In the night sky, look for Mars itself. It is a bright point with an orange-red tint that barely twinkles, unlike the stars. It becomes especially bright around opposition, when it is closest to Earth, and then fades noticeably. That change in brightness comes from the changing distance between the planets, and it is also why chances to leave for Mars come only about once every 26 months.
FAQ
When does Tianwen-3 launch?
It is aimed at the launch window between December 2028 and January 2029, with the samples planned to reach Earth around 2031. The schedule is not yet final.
Why bring samples back instead of studying them on Mars?
Rover instruments are limited in size and power, while Earth laboratories can analyse samples many times and in many ways. Some measurements, such as precise dating of rock, are very hard to do on Mars.
What is the hardest part?
The meeting in Mars orbit, where the ascent vehicle must reach the return craft and hand over the sample container. No spacecraft have done this around another planet before.
Can I see any of it in the sky?
The launch and cruise cannot be seen by eye. Watch the launch on a broadcast and follow the path in the orbit view. Mars itself is easy to find as a bright orange-red point in the night sky.
Related
- Tianwen-3 sample return
- ExoMars rover launch
- MMX — Martian moon sample return
- Mars — object index
- Phobos — object index
Times and figures are approximate — verify with official sources when planning travel. Simulation uses J2000 mean elements.