JAXA Unveils MMX Spacecraft for First-Ever Sample Return from a Martian Moon
Japan's JAXA unveiled the MMX spacecraft on August 13, 2026, targeting a world-first sample return from the Martian moon Phobos. The probe, the largest lunar or planetary spacecraft Japan has built, is scheduled to launch this autumn on an H3 rocket and return to Earth five years later.
On August 13, JAXA unveiled the spacecraft for its Martian Moons eXploration (MMX) mission to the press at the Tanegashima Space Center. Built by Mitsubishi Electric, the probe has a mass of roughly 4.2 to 4.5 tons—making it the largest lunar or planetary spacecraft Japan has ever developed—and has cost ¥55.3 billion (about $347.3 million) to bring to the launch pad. Its objective is a world first: land on Phobos, collect at least 10 grams of sand and rock, and return those samples to Earth.
The Martian Moons eXploration mission is currently scheduled to launch on a Japanese H3 rocket as early as this autumn. JAXA showed the probe to members of the media at Tanegashima on Thursday, August 13, 2026, and confirmed that the spacecraft is expected to return to Earth about five years after liftoff. The five-year timeline includes roughly a year of transit to Mars, three years orbiting Phobos to conduct sample collection, and the return leg.
The mission is led by JAXA in collaboration with NASA, CNES, DLR, and ESA. ESA is providing deep space communication equipment and ground station support for what would be the first successful attempt to land on a Martian moon and bring back surface material. The European contribution, along with participation from the other space agencies, helps underwrite the scientific return of the samples, which will be studied for clues about the origin of Phobos and the broader Mars system.
At roughly 4.2 to 4.5 tons, the MMX spacecraft is the heaviest probe Japan has ever sent beyond Earth orbit, and the ¥55.3 billion development cost reflects the engineering challenge of a round trip to the Mars system. The H3 rocket that will carry it has been in development as Japan’s next-generation heavy lifter, and a successful launch this autumn would set up the sample return for the early 2030s.
The samples from Phobos—if the mission succeeds—would be the first material ever brought back from a Martian moon, and only the second sample-return from the Mars system after NASA’s Mars Sample Return campaign, which is still in development. JAXA’s previous sample-return missions, Hayabusa and Hayabusa2, proved the agency’s ability to retrieve material from asteroids; MMX extends that capability to a moon of another planet.