Japan’s Martian Moons Exploration mission, MMX, is scheduled to launch aboard an H3 rocket from Tanegashima Space Center on October 20, Japan time. Led by the Japan Aerospace Exploration Agency, JAXA, with international participation, the mission will investigate Phobos and Deimos and attempt the first return of samples from a Martian moon. NASA is contributing instruments, communications and navigation assistance through its Deep Space Network, and funding for US scientists.
The moons’ origins remain unresolved: they could be asteroids captured by Mars’ gravity, or bodies assembled from debris expelled by a major impact on the planet. Measurements of Phobos’s composition could help distinguish between those hypotheses. Among the spacecraft’s 13 scientific instruments, NASA’s MEGANE detector will measure gamma rays and neutrons to identify chemical elements. Cameras, a laser instrument that measures surface distances, and an infrared instrument for surveying minerals will provide additional observations. MMX will also examine Deimos from farther away.
After reaching Mars in August 2027, MMX will conduct detailed surveys. In early 2029, it plans to deploy Idefix, a rover developed by Japanese, French, and German agencies, to help assess a landing site. Sample collection is planned for 2030, using equipment capable of extracting a shallow core or gathering loose material with nitrogen gas. The mission aims to return at least 10 grams to Earth in 2031, with the sample capsule landing by parachute in Australia before transport to Japan. NASA will receive approximately 15% of the material for preservation and research at Johnson Space Center in Houston.
