Japan Launches MMX Mission to Return First Samples From Mars
Japan Launches MMX Mission to Return First Samples From Mars Moon Phobos

TANEGASHIMA, Japan — Japan launched its Martian Moons eXploration spacecraft on an H3 rocket early Tuesday, beginning a five-year mission to land on Phobos, collect surface material and return it to Earth in 2031.

The Japan Aerospace Exploration Agency spacecraft lifted off at 4:41 a.m. Japan Standard Time from Tanegashima Space Center in southern Japan, corresponding to 3:41 p.m. EDT on Monday. JAXA confirmed separation of the MMX spacecraft from the rocket's upper stage roughly 71 minutes after liftoff and said the probe was in stable condition with solar panels deployed. Project manager Yasuhiro Kawakatsu described the spacecraft as being in a "very stable condition" shortly after separation.

Science Minister Yoshihiro Seki said at the launch site that MMX is "a challenging mission aiming for the world's first sample return from the Martian moons." He added that the agency hopes results from the mission will contribute to the development of Japan's space science and exploration technology.

The approximately $578 million mission is designed to collect at least 10 grams of regolith from Phobos, the larger of Mars' two moons. If successful, it would mark the first sample return from the Martian system. The spacecraft is expected to arrive in the vicinity of Mars in August 2027, enter a quasi-satellite orbit around Phobos, and spend roughly three years surveying the moon and selecting landing sites before attempting two soft landings. A small rover named Idefix, developed by the French and German space agencies, is scheduled to be deployed to help assess surface conditions.

Sampling will use two systems: a coring device mounted on a robotic arm and a pneumatic sampler that uses pressurized gas to collect loose surface material. After the second landing attempt, the spacecraft is planned to leave the Martian system in late 2030, make flybys of the smaller moon Deimos, and release a return capsule for recovery in Australia in 2031. Only the return module is expected to come back to Earth; the propulsion and exploration modules will be discarded.

Phobos and Deimos have long puzzled scientists. The moons may be captured asteroids or debris from a giant impact on Mars. Samples of Phobos material could help distinguish between those origins by revealing the presence or absence of water-related minerals and organic compounds, and by comparing the composition to known Martian and asteroidal material. Kawakatsu has said samples from Phobos would also provide data relevant to considering a Martian moon as a potential staging point for future human missions to Mars.

The mission carries 13 scientific instruments contributed by JAXA and international partners, including NASA, France's CNES, Germany's DLR and the European Space Agency. NASA provided a sampling device and a gamma-ray spectrometer. ESA is supporting communications through its deep-space network. The Idefix rover, which weighs about 25 kilograms on Earth but far less in Phobos' weak gravity, is named after the dog in the Asterix comics.

JAXA has prior experience with sample-return missions. The original Hayabusa spacecraft returned microscopic grains from asteroid Itokawa in 2010, and Hayabusa2 returned more than 5 grams from Ryugu in 2020. MMX builds on that expertise but faces additional challenges, including the low gravity of Phobos, communication delays of roughly 20 minutes, and the need for autonomous landing operations.

The H3 rocket used for the launch is Japan's current flagship vehicle. The flight was designated H3 Flight No. 10. A backup launch window had been reserved through early November if the primary date could not be used, but the launch proceeded as scheduled. JAXA reported that the rocket performed as planned.

No samples from Phobos or Deimos have previously been returned to Earth. Several earlier attempts to reach the moons, including Russia's Phobos-Grunt mission in 2011, failed before leaving Earth orbit or reaching their targets. MMX is the first dedicated effort to land on and sample Phobos.

The spacecraft will travel roughly 500 million to 600 million kilometers before entering the Martian system. Once there, it will map Phobos' topography, composition and gravity field while searching for scientifically interesting and operationally safe landing sites. The landings themselves are expected to last only a few hours each.

Recovery of the sample capsule in Australia is planned for 2031, following the same general approach used for the Hayabusa missions. One gram of the returned material is expected to be distributed promptly for initial analysis by Japanese and international scientists, with the remainder curated at JAXA's Extraterrestrial Sample Curation Center in Sagamihara for longer-term study.

The launch marks the start of Japan's most ambitious planetary mission to date and the first attempt to bring material from a moon of another planet back to Earth. Success would provide direct laboratory access to Phobos material and new constraints on the formation of the Martian moons and the early delivery of water and organics in the inner solar system.