JAXA’s MMX Mission to Return Samples From Mars’ Moon Phobos

JAXA’s Martian Moons eXploration (MMX) is designed to do something no mission has yet achieved: study both moons of Mars, land on Phobos, collect material from its surface and return that sample to Earth. The mission is also intended to demonstrate technologies for future exploration of the Martian system. 1821

MMX launch date, time and location

JAXA has scheduled MMX for launch aboard H3 Flight 10 on October 20, 2026, at 04:41:03 Japan Standard Time. The launch site is the Yoshinobu Launch Complex at the Tanegashima Space Center in Japan. 2

The reserved launch period runs from October 21 through November 7, 2026. JAXA says the launch time would be set separately for each day during that backup period, so the October 20 time should not be treated as the time for every possible attempt. 25

What MMX is designed to do

MMX combines three mission roles: it will operate as an orbiter in the Martian system, conduct close observations and surface operations at Phobos, and carry a sealed return capsule for the journey back to Earth. Its scientific program is built around four connected goals:

• determine how Phobos and Deimos formed;
• study their geology, composition, internal structure and surface environments;
• examine how the moons interact with Mars and the surrounding environment; and
• bring Phobos material to Earth for laboratory analysis. 172440

The spacecraft carries 11 scientific instruments. Some measurements will be made remotely, while the returned sample will allow laboratory studies of mineralogy, composition, isotopes and age that cannot be performed with remote sensing alone. 2942

International partners and spacecraft contributions

JAXA leads MMX in cooperation with NASA, CNES, DLR and ESA. The partnership includes contributions to instruments, communications, ground support and sampling hardware. 183435

The mission also carries IDEFIX, a small rover jointly developed by CNES and DLR. IDEFIX is planned to reach the Phobos surface before the main spacecraft and investigate the moon’s regolith and physical properties. Those measurements are intended to improve landing and sampling safety while also providing scientific and calibration data. 2937

MMX travel and operations timeline

The current mission profile is approximately five years from launch through the return to Earth:

1. 2026: MMX launches from Tanegashima aboard H3 Flight 10.
2. About one year later: The spacecraft reaches the vicinity of Mars and enters the Martian system, with arrival planned for fiscal year 2027. 2124
3. About three years in the Martian system: MMX conducts remote sensing, orbital operations and reconnaissance, selects a landing site on Phobos, deploys IDEFIX and attempts surface operations and sampling. 2031
4. After exploration and sampling: The spacecraft departs the Martian system and begins its return journey.
5. FY2031: JAXA’s current planning target is Earth return, when the sample capsule is expected to arrive with Phobos material. 2130

These are mission plans rather than completed events, and dates may change as development, launch and operations proceed.

How MMX will sample Phobos

MMX is planned to make up to two touchdowns at different locations on Phobos. It will use independent coring and pneumatic sampling systems to collect more than 10 grams of regolith. Sampling multiple sites is intended to improve the scientific value of the returned material and provide operational redundancy. 3639

The IDEFIX rover’s earlier surface work is important because Phobos is a small, irregular, low-gravity body. Learning how its loose surface behaves should help mission controllers assess the risks faced by the larger spacecraft during landing and sample collection. 29

What MMX will observe on Phobos and Deimos

Phobos is the mission’s sampling target and will receive the most detailed surface and orbital investigation. MMX will study its topography, composition, gravity, internal structure and surface environment while using those observations to choose a scientifically valuable and operationally safe sampling area. 2426

Deimos will also be observed, but the planned sample-collection and landing operations are at Phobos. The mission profile includes remote observations and close approaches to both moons, followed by additional Deimos observations before the spacecraft leaves the Martian system. 172431

The central mystery: where did the moons come from?

The leading explanations for Phobos and Deimos have different implications for Mars and the early Solar System. One possibility is that they are primitive asteroids captured by Mars’s gravity. Another is that they formed from debris thrown into orbit after a giant impact on Mars. 4041

A returned Phobos sample could help distinguish between those possibilities. Scientists can compare its minerals, bulk chemistry, isotopic signatures and radiometric ages with known asteroid material and with expectations for material derived from Mars. The result could clarify the moons’ origins, improve understanding of Mars’s early history and shed light on how the terrestrial planets evolved. 4142

The evidence is not limited to the sample itself. MMX’s observations of both moons, their surfaces and their relationship with Mars will provide the geological context needed to interpret what the sample represents.

When and where will the samples return to Earth?

JAXA’s current target is fiscal year 2031 for the return of MMX’s sample capsule to Earth. The cited official mission material specifies the return year, but it does not establish a final Earth landing or recovery location. Any more specific location should therefore be treated as provisional unless JAXA later confirms it. 2130

Why MMX matters for future Mars exploration

MMX extends the sample-return approach demonstrated by JAXA’s Hayabusa2 mission into the much more demanding Martian environment. The mission will test autonomous navigation near a small body, operations in a low-gravity environment, surface mobility, precision landing, sample acquisition, containment and atmospheric re-entry. 2026

JAXA also presents MMX as a step toward understanding whether Mars’s moons could support future exploration activities or serve as useful locations in a broader Mars-exploration architecture. The mission’s immediate goal is scientific—returning Phobos material—but its engineering lessons could shape later robotic and crewed missions to the Martian system. 2026