Japan plans first sample-return mission to Mars moon Phobos

Japan is scheduled to launch its Martian Moons eXploration spacecraft on Tuesday, October 20, seeking to become the first country to bring material from a moon of Mars back to Earth. The uncrewed MMX probe will travel aboard an H3 rocket from the Tanegashima Space Center at 4:41 am Japan time, according to a launch schedule attributed to the Japan Aerospace Exploration Agency by The Economic Times.

That schedule corresponds to 1:11 am Indian Standard Time on Tuesday. If the journey proceeds successfully, the spacecraft is expected to reach the vicinity of Mars around August 2027 and enter orbit around Phobos, one of the planet's two moons.

The mission calls for a later landing on Phobos to gather at least 10 grams of surface material. MMX is expected to spend about three years near Mars, and will also observe the smaller moon Deimos without landing on it.

Small samples, a large question about planetary origins

The central scientific question is how Mars acquired its two moons. Under the giant-impact hypothesis, a collision between Mars and another celestial body produced material from which the moons formed. The competing capture hypothesis proposes that Phobos and Deimos were asteroids caught by the planet's gravity.

JAXA hopes the returned material will help distinguish between these explanations and clarify the formation history of Mars and its moons. The agency links that question to a broader investigation of how conditions suitable for life could have developed on the terrestrial planets—Mercury, Venus, Earth and Mars.

These are research objectives, not findings already established by the mission. MMX's sample target is the surface of Phobos, rather than Mars itself.

Testing a route for future human exploration

The project involves US and European space agencies alongside universities and technology companies. Beyond its scientific goals, it is intended to develop capabilities relevant to eventual human exploration of the Martian region.

JAXA also wants to assess whether Phobos could serve as a staging location for future missions. Demonstrating the requirements for travel to the moon and back would contribute to that assessment; MMX does not itself carry astronauts or establish a crewed outpost.

A different target from Mars surface-return plans

The mission runs alongside international efforts to retrieve material directly from Mars. NASA's Perseverance rover has been operating on the planet since 2021 and has collected samples. The report describes the US return mission as effectively cancelled by President Donald Trump's administration following a congressional vote in January 2026.

China's Tianwen-3 mission is scheduled to launch around 2028, with the ambition of returning Mars samples as early as 2031. That timetable could put its return ahead of MMX, although the missions target different bodies and both depend on successful execution of their planned journeys.