Summary
JAXA’s MMX mission is targeting an October 2026 launch to study Mars’ moons and return a sample from Phobos. NASA is contributing a composition-measuring instrument, sampler technology, communications support and scientific expertise.
Japan’s space agency, JAXA, is targeting 3:41 p.m. EDT on Monday, October 19, 2026, for the launch of its Martian Moons eXploration mission, or MMX, from Tanegashima Space Center. That is 4:41 a.m. JST on Tuesday, October 20. NASA is contributing instruments, sampler technology, communications and navigation support, and funding for US scientists on the mission team.
MMX aims to study both of Mars’ moons, Phobos and Deimos, and bring a sample of Phobos to Earth. The mission could help resolve a long-running question: whether the moons formed from material thrown into orbit by a major impact on Mars or are asteroids that the planet captured with its gravity billions of years ago.
Two possible origins for Mars’ moons
The two explanations imply different histories for the moons and the material from which they formed. NASA says MMX’s observations and returned sample are intended to help distinguish between them. Resolving the question could also shed light on the early history of the inner Solar System, when Earth and neighbouring planets may have been acquiring much of their water and organic compounds.
How MMX will study and sample Phobos
NASA’s MEGANE instrument will measure neutrons and gamma rays emitted from Phobos’ surface. Those measurements can help scientists determine the moon’s elemental composition, providing clues about its origin. MEGANE was developed by the Johns Hopkins Applied Physics Laboratory.
NASA is also providing the Pneumatic Sampler, or P-Sampler, technology demonstration. Mounted on a spacecraft landing leg, it is designed to collect surface material using bursts of high-pressure nitrogen gas. It will complement JAXA’s C-Sampler, which is intended to extract cores from a few inches below the surface. NASA’s Deep Space Network will provide communications and navigation support.
After arriving at Mars in August 2027, MMX is due to survey both moons, with a detailed survey of Phobos before sampling. The spacecraft is scheduled to collect Phobos material no earlier than December 2028 and deliver it to Earth in 2031. NASA says it will obtain and curate about 15% of the returned sample at the Astromaterials Lab at Johnson Space Center in Houston, where portions will be made available to researchers for decades.