Tianwen-3 samples return
China's Tianwen-3 aims to launch in 2028 and bring Martian soil and rock back to Earth by 2031. If it succeeds, samples from Mars will reach laboratories on Earth for the first time.
The story
Tianwen-3 is China's plan to bring soil and rock from Mars back to Earth. The aim is to launch in 2028 on two separate Long March 5 rockets and to return the samples to Earth by 2031. The amount to be returned has been reported as around 500 grams. If the plan works, it will be the first time samples collected directly on Mars reach a laboratory on Earth.
The mission is split into two parts. One rocket will carry a lander and a small ascent rocket; the other will carry an orbiter that circles Mars and a return craft that comes back to Earth. After the lander drills into the ground and collects samples, the ascent rocket will lift off from the Martian surface with them and meet the orbiter. The return craft will then take the samples and head home.
Once samples reach Earth, scientists can do things that no rover on Mars can do. A rover can carry only a few instruments because of limits on weight and power. In laboratories on Earth, large electron microscopes and precise instruments can measure the age of the rocks and study their tiniest structures. The main goal of Tianwen-3 is to look for signs that life once existed on Mars.
When the samples arrive, they will not be opened straight away. International rules say Martian samples must first be examined inside a special sealed facility. Germs from Earth could spoil the results, and any unknown material from Mars must also be kept from escaping. The schedule may change, and this article will be updated.
Mission goals
For nearly 50 years since NASA's Viking landers in 1976, the question of whether Mars ever had life has not found a clear answer. When instruments on Mars gave uncertain results, there was no way to test the same sample again. Samples brought back to Earth can be stored for decades and analysed again whenever better techniques appear.
Bringing samples back from Mars is considered one of the hardest tasks in robotic exploration. A rocket must launch from the surface of another planet, meet another spacecraft in orbit, hand over the samples, and then travel back to Earth, and every step has to work. Success would also help prepare for a future trip in which people travel to Mars and return.
China has already brought back samples from the Moon twice. Chang'e 5 returned samples from the near side in 2020, and Chang'e 6 brought back the first samples from the far side in 2024. Those missions practised landing, lifting off, meeting in orbit and returning home, and Tianwen-3 was designed on the basis of that experience. Chang'e 6 in particular collected its samples on the far side of the Moon, where a spacecraft cannot talk directly to Earth.
Mission chronology and background
China's first Mars mission, Tianwen-1, succeeded in 2021 in sending an orbiter, a lander and the rover Zhurong to Mars all at once. Tianwen-2 launched in 2025 and is on its way to collect samples from Kamoʻoalewa, a small asteroid that travels near Earth. Tianwen-3 adds one more step: lifting off from the surface of Mars.
NASA and ESA have also been planning to return samples from Mars. The Perseverance rover has collected samples in Jezero Crater and sealed them in tubes to be picked up later. However, the estimated cost grew to as much as 11 billion dollars, the plan was put under review in 2024, and its future is still unclear.
Quarantine rules for Martian samples follow the planetary protection guidelines of the international Committee on Space Research, known as COSPAR. The samples must be opened in a sealed facility at biosafety level 4, and nothing may leave until it has been judged safe. Moon rocks and astronauts from Apollo 11, 12 and 14 were isolated for the same reason, and the rule was lifted once the Moon was judged to be lifeless.
Other milestones of this mission
Where to see it — sky and simulator
Tianwen-3 has not launched yet, so there is no track for it in NowSky's orbit view. It will be added to the list of spacecraft once its orbit data are published after launch. In the meantime, move the time in the orbit view to late 2028 or to 2031 to see where Earth and Mars will be around the Sun at launch and at return.
Select Mars in the sky view to see when it rises from your location, how high it climbs and in which direction it lies. Several regions in Mars's northern hemisphere are being studied as landing sites, including Utopia Planitia, Chryse Planitia and the Arabia Terra area. Once the actual landing site is chosen, it will be added to this article. The list is being narrowed down by weighing landing safety against scientific value.
FAQ
When does it launch?
Two launches on separate rockets are planned for 2028. The goal is to bring the samples back to Earth by 2031.
How much sample will it bring back?
The amount has been reported as around 500 grams. That may sound small, but it is enough for laboratories around the world to share and study for many years.
Why bring the samples to Earth?
A rover on Mars can run only a few kinds of analysis because of limits on weight and power. In laboratories on Earth, scientists can measure the age of rocks precisely, examine their tiniest structures and check possible signs of life again and again with different methods.
What happened to NASA's Mars sample return?
Its costs rose sharply and it went under review in 2024, and its future plan is still not settled. The sample tubes collected by Perseverance remain on Mars.
Related
- Tianwen-3 launch
- Perseverance launch
- Curiosity launch — Mars rover
- Mars — object index
- Perseverance — object index
Times and figures are approximate — verify with official sources when planning travel. Simulation uses J2000 mean elements.