Tanegashima, October 14 — The Japan Aerospace Exploration Agency is set to launch the Martian Moons eXploration mission on Monday at 19:41 UTC from the Tanegashima Space Center in Japan. The mission will be carried aboard the H3 launch vehicle in its most powerful configuration, marking the first use of the H3 rocket for an interplanetary mission. This launch represents a significant milestone for Japan’s deep-space ambitions, coming after the H3’s first successful flight in February 2024 following an initial test failure in 2023.
At its heart, MMX seeks to solve a long-standing mystery: whether Mars’ moons Phobos and Deimos are captured asteroids or formed from debris after a giant impact on Mars. The spacecraft will enter Mars orbit in 2025, conduct detailed observations of both moons, land on Phobos to collect regolith samples, and depart for Earth, with sample return expected in 2029.
If successful, MMX will be the first mission to return a sample from a Martian moon, providing critical insights into the formation and evolution of the Martian system. The mission’s total cost is approximately 41.3 billion Japanese yen, equivalent to about US$270 million at current exchange rates. JAXA developed the H3 rocket as Japan’s next-generation launch system to replace the H-IIA, featuring improved reliability and lower launch costs.
International collaboration is central to the effort, with instruments contributed by NASA, ESA, and CNES, reflecting broad planetary science partnership.
Mission Design and Scientific Goals
MMX will study Mars’ two moons, Phobos and Deimos, using a suite of seven scientific instruments. These include TENGOO for detailed terrain imaging, OROCHI for wide-field visible light observations, LIDAR for surface altitude and albedo measurements, MIRS for near-infrared mineral characterization, and MEGANE — a neutron and gamma-ray spectrometer provided by NASA to analyze elemental composition. The spacecraft will operate in quasi-satellite orbits around the moons due to their insufficient mass for conventional satellite orbits.
The probe is designed to land on Phobos once or twice to collect regolith samples using a pneumatic sampling system. After sampling, it will conduct flybys of Deimos before releasing a return capsule for Earth.
The mission aims to return at least 10 grams of material from Phobos’ surface, enabling laboratory analysis to determine the moons’ origin and composition.
Historical Context and Future Steps
MMX was first announced on 9 June 2015, with official project approval occurring on 19 February 2020. The probe arrived at Tanegashima Space Center on March 31, 2026, and final systems checks were completed over the weekend ahead of launch. Weather forecasts show favorable conditions for the scheduled launch window.
Launch preparations are proceeding nominally, with all systems verified. Following launch, the spacecraft will enter Mars orbit in 2025.
Sample return to Earth is expected in 2029, though some background estimates suggest a later date of 2031 based on mission timelines. The mission will be led by Yasuhiro Kawakatsu, with JAXA overseeing execution. Success would mark a major advancement in robotic sample return capabilities and deepen understanding of Martian system evolution.
