Japan’s Martian Moons eXploration mission launched from Tanegashima Space Center on October 20, 2026, beginning a journey intended to return material from Phobos, the larger of Mars’s two moons. The Japan Aerospace Exploration Agency reported the launch, stating that the H3 rocket lifted off at 4:41:03 a.m. Japan Standard Time and separated the spacecraft 71 minutes and 13 seconds later.
JAXA reported completion of the initial operations phase on October 21. The agency confirmed deployment of the solar arrays, establishment of three-axis attitude control, and release of the medium-gain antenna. The mission then entered initial equipment checks and preparations for its interplanetary cruise.
These are spacecraft operations completed near Earth. The encounter with Mars, surface sampling, and return to Earth remain later stages of the mission.
Testing the Origin of Mars’s Moons
The mission is designed to investigate how Phobos and Deimos formed. One explanation is that Mars captured objects that originated elsewhere in the solar system. Another is that an impact involving Mars produced material from which its moons developed. Measurements of a returned sample can test the composition and history of the material directly.
JAXA plans to combine laboratory analysis with observations made around Mars. Remote measurements provide information about the moons’ surfaces and the setting from which the sample is collected. Laboratory instruments on Earth can investigate selected grains with methods that cannot all be carried aboard one spacecraft.
Phobos is the sampling target. Its weak gravity also makes it a different landing environment from Mars itself. JAXA’s mission design draws on experience developed through its Hayabusa asteroid missions, which involved approaching small bodies and returning extraterrestrial material.
Sampling and the Return Journey
The planned arrival at Mars is in 2027. Near Phobos, the spacecraft will use a quasi-satellite orbit: it will travel around Mars in a path that keeps it near the moon. Observations from that position will help the team study the surface and choose suitable landing locations.
The sampling objective is at least 10 grams of Phobos material. The mission also includes observations of Deimos, rather than a separate sample return from that moon. JAXA’s published sequence calls for departure from the Mars system in 2030 and return of the sample capsule to Earth in 2031.
The returned material may also contain information about Mars. Impacts can eject material from the planet, and some of it can reach Phobos. Identifying such material would require analysis of the actual sample; the mission’s target remains Phobos rather than a landing on the Martian surface.
Instruments and International Contributions
International partners are supplying instruments and operational support. NASA’s contributions include the MEGANE gamma-ray and neutron instrument, a pneumatic sampling device, and ground-station support. Gamma-ray and neutron measurements help determine the elemental composition of the surface.
France’s space agency, CNES, contributes the MIRS infrared instrument and works with the German Aerospace Center, DLR, on the IDEFIX rover. The rover is intended to investigate surface conditions before the main spacecraft’s sampling operations. DLR also contributes testing capabilities, and the European Space Agency supports communications through its ground network.
The mission’s Phobos sample-return approach brings together those measurements rather than relying on one instrument to settle the origin question. Composition measured from a distance, observations at the surface, and laboratory examination of returned material provide different kinds of evidence.
Australia is the planned destination for recovery of the returning capsule in 2031. The Australian Space Agency describes the recovery activity as part of its cooperation with Japan. Before that return, the immediate operational work is to complete spacecraft checkout and prepare the cruise that will take MMX to the Mars system.
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