JAXA Martian Moons eXploration (MMX) Sample Return

The Martian Moons eXploration mission, developed by the Japan Aerospace Exploration Agency with contributions from NASA, CNES, and DLR, is scheduled to launch during the November-December 2026 Mars launch window. MMX will travel to Phobos, the larger of Mars's two moons, collect at least 10 grams of surface material, and return those samples to Earth in 2031 — making it the first-ever sample return from the Mars system and one of the most scientifically consequential missions in planetary science history. Phobos is an enigmatic body. Its origin remains fiercely debated: it may be a captured carbonaceous asteroid, or it may be debris ejected from Mars's surface by a giant impact billions of years ago. Distinguishing between these hypotheses has profound implications for understanding Mars's early history, the delivery of water and organics to the inner Solar System, and the feasibility of using Phobos as a waystation for human Mars missions. MMX's scientific payload includes the MEGANE gamma-ray and neutron spectrometer (NASA), the OROCHI wide-angle camera, the TENGOO telescopic camera, the LIDAR altimeter, and an internationally contributed seismometer package. MMX will spend approximately three years in the Mars system before departing for Earth. During that time it will also conduct a brief reconnaissance of Deimos, Mars's smaller moon. The spacecraft has a launch mass of approximately 4,000 kilograms and uses a novel sample collection system developed from lessons learned in JAXA's successful Hayabusa2 mission, which returned asteroid samples in 2020. The mission's 5-year round trip makes it the longest-duration sample return mission ever attempted, and its success would firmly establish Japan as the world's premier practitioner of robotic sample return science.