MMX (Martian Moons eXploration)
Japan's mission to bring back the first sample from a moon of Mars.
Key facts
- Agency
- Japan Aerospace Exploration Agency (JAXA)
- Type of mission
- Orbiter, lander and sample return
- Target
- Phobos and Deimos, the moons of Mars
- Launched
- 20 October 2026
- Status
- On its way to Mars
Mars has two small, dark moons, Phobos, about 22 kilometres across, and Deimos, about 12 kilometres across. Their colours resemble certain dark asteroids, which led to the idea that they are captured asteroids. Their nearly circular orbits, close to Mars's equator, point instead to a giant impact on Mars that threw out a ring of debris from which they formed. MMX is designed to settle the question.
The plan
MMX launched on an H3 rocket from Tanegashima on 20 October 2026. It is due to reach Mars in 2027 and spend about three years studying both moons. It will land on Phobos, collect at least 10 grams of surface material with a coring device and a pneumatic sampler, and carry it home, with the capsule due back in 2031. It also carries a small rover, built by the French and German space agencies, to drive on Phobos, and instruments from NASA and Europe.
What the sample could tell us
If Phobos is a captured asteroid, its soil should match a type of meteorite, perhaps a carbonaceous chondrite. If it formed from Martian debris, it should look like Martian rock altered by impacts. Either way, the surface of Phobos should also hold a sprinkling of Martian material, blasted off the planet by impacts over billions of years. That would be the first sample of Mars returned to Earth, though in tiny amounts.
Why it matters to meteorites
It builds on Japan's Hayabusa missions and gives a direct test of the link between dark asteroids and carbonaceous chondrites.
Key dates
| Date | What happened |
|---|---|
| 20 October 2026 | MMX launched on an H3 rocket from the Tanegashima Space Center. |
| 2027 | Planned arrival at Mars. |
| 2031 | Planned return of the sample capsule to Earth. |
See where this mission fits among all the others in the mission timeline.
Did you know?
Phobos orbits Mars three times a day and is slowly spiralling inwards; in tens of millions of years it will break up or crash.
The MMX rover, called IDEFIX, is about the size of a microwave oven.