NASA Details Role in Japan’s Planned Mission to Mars’ Moons

NASA is contributing science instruments, communications support and sample-curation work to Japan’s Martian Moons eXploration mission, or MMX, which is designed to investigate the origins of Phobos and Deimos and bring a sample of Phobos back to Earth.

The Japan Aerospace Exploration Agency, or JAXA, is targeting a launch from Tanegashima Space Center at 3:41 p.m. EDT on Monday, Oct. 19, 2026. That corresponds to 4:41 a.m. Japan Standard Time on Oct. 20, according to NASA’s announcement dated Oct. 15.

NASA’s role includes the Mars-moon Exploration with Gamma rays and Neutrons instrument, known as MEGANE, a pneumatic sampling technology demonstration, and support from the agency’s Deep Space Network for communications and navigation. NASA is also funding U.S. researchers participating in the mission’s science team.

MEGANE will measure gamma rays and neutrons from Phobos to help determine the moon’s elemental composition. NASA says those measurements can provide evidence relevant to how the moon formed. The instrument was developed by the Johns Hopkins Applied Physics Laboratory.

The NASA-developed P-Sampler is mounted on a landing leg and is intended to collect surface material by releasing high-pressure nitrogen gas. It will work alongside JAXA’s C-Sampler, which is designed to take samples from several inches below the surface. Honeybee Robotics, a Blue Origin company, developed the pneumatic sampler mechanism, NASA said.

NASA expects to receive and curate about 15% of the returned material at the Astromaterials Lab at Johnson Space Center in Houston. The agency says it will make its portion available to researchers for decades. NASA Associate Administrator Nicky Fox described the collaboration on sample curation as valuable and said the samples could support long-term study of the Mars system.

The mission addresses an open scientific question: whether the moons formed from debris created by a large impact on Mars or are asteroids captured by the planet’s gravity. NASA program executive and scientist Tom Statler said resolving their origin could help researchers understand conditions in the early inner solar system, including the period when Earth and other inner planets may have acquired water and organic compounds.

NASA’s announced schedule calls for MMX to reach Mars in August 2027 and begin surveying both moons. Following detailed observations of Phobos, the spacecraft is planned to collect a sample no earlier than December 2028 and return it to Earth in 2031. These are mission targets, not completed milestones.

NASA said its MMX contributions were developed through the agency’s Discovery Program, managed by Marshall Space Flight Center for the Science Mission Directorate. The mission is a NASA-JAXA scientific partnership, with researchers from the United States and other countries expected to work with mission data and the returned sample.