Japan's MMX Mission: Bringing Back Soil from Phobos, a Moon of Mars
Japan's space agency, JAXA (Japan Aerospace Exploration Agency), is set to launch the Martian Moons eXploration (MMX) spacecraft on its H3 rocket from the Tanegashima Space Center. The planned launch time is 04:41 Japan time on 20 October 2026, with a reserve window up to 9 November 2026.
MMX will travel to Mars, study its two small moons, Phobos and Deimos, and land on Phobos to collect at least 10 grams of its soil.
The soil will come back to Earth in a capsule in 2031. The capsule will land in Australia. The whole mission will take about five years.
Scientists hope the samples will settle an old question: did Phobos and Deimos form from debris thrown up when a big object hit Mars, or are they asteroids that Mars captured with its gravity?
The mission is international. NASA (USA), CNES (France), DLR (Germany) and ESA (Europe) are partners. A small rover named Idefix, built by France and Germany, will drive on Phobos.
If it succeeds, MMX will be the first mission to bring back material from the Mars system.
Martian Moons eXploration (MMX) Mission: Japan's Journey to Phobos
The Martian Moons eXploration mission, or MMX, is a Japanese robotic spacecraft that will fly to Mars, land on its larger moon Phobos, scoop up some of its soil and bring it back to Earth. It is led by JAXA, Japan's national space agency. It is a "sample return" mission: its main job is not just to take photos, but to carry real pieces of another world back home so scientists can study them in laboratories. If successful, it will be the first time any country brings back material from Mars or its moons.
The launch of MMX from Tanegashima begins Japan's five-year attempt to bring back the first soil from the Mars system. The samples, due in 2031, are expected to answer whether Phobos is a captured asteroid or a piece of Mars blasted off by a giant impact.
Sample Return Missions: Bringing Pieces of Space Back to Earth
A sample return mission is a space mission that travels to another world, such as the Moon, an asteroid, a comet or a planet's moon, collects some of its material and brings it back to Earth. The material may be soil, rock, dust or even particles of the solar wind. Scientists then study it in powerful laboratories on Earth. This is the most direct way to learn what other worlds are made of and how the solar system formed.
MMX adds a new kind of target to the list of sample return missions: a moon of another planet. Japan already holds the record of two successful asteroid sample returns, and MMX aims to extend that skill to the Mars system for the first time.
- MMX launch: H3 rocket (Flight No. 10), Tanegashima Space Center, planned 20 October 2026 at 04:41 JST; reserve window to 9 November 2026
- Mission length: about 5 years; Mars orbit August 2027; Phobos sampling 2030; Earth return 2031
- Sample target: at least 10 grams of Phobos soil; capsule to land in Australia
- Idefix rover: about 25 kg, built by CNES (France) and DLR (Germany)
- NASA instrument on board: MEGANE (gamma-ray and neutron spectrometer)
- Phobos: about 6,000 km above Mars, orbit of 7 h 39 min; Deimos: 30.3 h orbit
- Both moons discovered by Asaph Hall, August 1877
- JAXA formed 1 October 2003 by merging ISAS, NAL and NASDA