Tianwen-3 samples return

If all goes to plan, Martian soil reaches Earth laboratories for the first time.

The story

If all goes to plan, in 2031 the return capsule of Tianwen-3 will enter Earth's atmosphere carrying about 500 g of Martian soil — the most important geological sample since the Apollo Moon rocks. Two launches are planned for 2028, with a lander, ascent vehicle, orbiter and return craft meeting at Mars.

Martian samples in Earth laboratories allow what no rover can do: isotopic dating, electron-microscope analysis of microstructure, and the verification of any trace of life. The debate over life on Mars is likely to divide into before and after this delivery.

The first thing to do when the samples arrive is not to open them. Under planetary-protection rules Martian material must pass quarantine in a sealed facility, and only handling free of terrestrial contamination makes any argument for Martian life stand up. The receiving facility and the quarantine procedure draw as much attention as the samples themselves.

As the Apollo rocks have yielded new discoveries for more than half a century, these 500 g will be re-analysed in laboratories worldwide for decades. With NASA and ESA's Mars Sample Return under review since 2024, Tianwen-3 would, if on schedule, be the first to bring Martian samples home. Schedule changes will be updated in this article.

Why it matters

For fifty years since Viking (1976) the question of past life on Mars has been stuck at the limits of a rover laboratory. Instruments in the field can run only a few analyses under mass and power constraints, and an ambiguous result cannot be rechecked. Laboratories on Earth can revisit the same sample for decades with new techniques.

Mars sample return is the most complex robotic mission in space exploration. Launching a rocket from the Martian surface, meeting another spacecraft in orbit and returning to Earth are each a first, and success would be a rehearsal for a crewed Mars round trip.

That China may bring back samples first while American and European plans falter on budget marks a shift in the landscape of exploration. The lunar sample returns of Chang'e 5 (2020) and Chang'e 6 (2024) are the foundation of Tianwen-3's design.

How to watch

Tianwen-3 has not yet launched, so the orbit view has no track for it; once orbital data are published after launch it will be added to the probe list. Candidate landing sites under study include the northern lowlands of Utopia and Chryse.

Select Mars in the sky view for its altitude, bearing and rise time from your location. Mars's position at the late-2028 launch window and at the 2031 return can be previewed by moving the time in the orbit view.

NASA publishes the locations of the sample tubes Perseverance has left in Jezero Crater, and the American–European plan to retrieve them can be compared alongside Tianwen-3's schedule.

Background

Tianwen-1 (2021) was China's first Mars mission and succeeded with an orbiter, a lander and the rover Zhurong in one go; Tianwen-2 (launched 2025) is to sample the Earth quasi-satellite Kamoʻoalewa. Tianwen-3 adds a launch from the Martian surface to that experience.

A plan for international joint research on the returned samples has been announced, with foreign teams to take part in allocation and analysis. A sample-quarantine facility is to be built in China.

NASA and ESA's Mars Sample Return targeted a 2033 return but went into review in 2024 as costs reached 11 billion dollars; as of 2026 a reduced version is under study. The tubes Perseverance filled remain in Jezero Crater.

Quarantine rules for Martian samples follow the planetary-protection guidelines of the Committee on Space Research (COSPAR). Mars is classed as “restricted Earth return”: samples must be opened in a containment facility at biosafety level 4, and nothing may leave it until judged free of anything non-terrestrial. The Apollo Moon rocks went through the same procedure for the first three landings in 1969 until the Moon was judged lifeless. For Martian samples that judgement is far harder, and the quarantine is expected to last longer.

FAQ

When does it launch?

Two launches are planned for 2028, with return targeted for 2031.

How much sample will it return?

About 500 g is planned.

Why bring samples to Earth?

Isotopic dating, microstructural analysis and verification of biosignatures are possible only in Earth laboratories.

What happened to NASA's sample return?

It went into review in 2024 over cost; a reduced version is under study and no return date is set.

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Times and figures are approximate — verify with official sources when planning travel. Simulation uses J2000 mean elements.