A Japanese spacecraft is scheduled to leave Tanegashima Space Center at 3:41 p.m. EDT on Monday, Oct. 19, 2026, bound for the moons of Mars. The Martian Moons eXploration mission, called MMX, is run by JAXA, Japan’s space agency, and its centerpiece is a plan to scoop up material from the surface of Phobos and bring it back to Earth in 2031. Launch is still days away, so the mission has not yet left the ground.
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In Japan the same instant falls at 4:41 a.m. on Tuesday, Oct. 20, local time. Everything that follows the liftoff is a long game: a cruise to Mars lasting nearly a year, months of mapping two small and poorly understood worlds, and then the delicate business of touching down on one of them to collect a sample that scientists on several continents are already waiting to study.
Launch from Tanegashima and the road to Phobos
According to NASA’s mission overview, the spacecraft is due to arrive at Mars in August 2027, at which point it begins surveying Phobos and Deimos, the planet’s two moons. Sample collection comes no earlier than December 2028, only after the survey has shown where a landing is safe and scientifically worthwhile. The return of the sample to Earth is scheduled for 2031. The survey period comes first so the team can pick a landing site with evidence in hand, and the plan allows a long stretch of observation before any sampling attempt.
The mission is built to settle an argument about where the moons came from. NASA notes that scientists remain divided between two explanations: that the moons are remnants of a massive impact on Mars, or that they are ancient asteroids captured by the planet’s gravity billions of years ago.
Tom Statler, MMX program executive and program scientist at NASA Headquarters, framed the impact idea this way: “Phobos and Deimos may be the remains of a massive impact on Mars”. The competing capture hypothesis would make the moons something quite different, rock that formed elsewhere and wandered in. A returned sample of Phobos, studied in laboratories on Earth, can test those stories far more sharply than any instrument flown past the moons.
MEGANE and the pneumatic sampler on NASA’s side
The United States is contributing hardware as well as money. NASA supplied the MEGANE instrument, short for Mars-moon Exploration with Gamma rays and Neutrons, which was developed by the Johns Hopkins Applied Physics Laboratory. The spectrometer measures neutrons and gamma rays coming off the surface of Phobos, and from them scientists can work out which chemical elements the moon contains. Reading that composition from orbit helps the team decide where the sampler should go, before any machine touches the ground. Background on the project sits on the MMX mission page.
NASA also provided a technology demonstration called the P-Sampler, short for Pneumatic Sampler. Mounted on a landing leg, it uses bursts of high-pressure nitrogen gas to gather loose surface material. Honeybee Robotics, a Blue Origin company, developed the mechanism. It works alongside JAXA’s own C-Sampler, which, NASA says, extracts cores from a few inches deeper than the gas-driven device can reach. Having two methods gives the mission a better chance of returning something useful if one approach struggles with the moon’s surface.
Communications and navigation come from NASA’s Deep Space Network, the worldwide set of large antennas that tracks spacecraft far from home. NASA is also paying for U.S. scientists to sit on the MMX science team, a group introduced when NASA selected 10 scientists for the international mission.
A 2031 return and NASA’s 15 percent share
When the capsule comes home, NASA will curate about 15% of the returned sample at the Astromaterials Lab at Johnson Space Center in Houston. More about that laboratory is available on the Johnson Space Center astromaterials site. The roughly 15% share means researchers in the United States will hold part of the Phobos material directly, while the rest of the returned sample is handled under the Japanese-led mission, giving scientists on both sides of the Pacific samples to study.
Nicky Fox, associate administrator of NASA’s Science Mission Directorate, said, “The samples from MMX will bring forth paradigm-shifting science on the Mars system for generations to come”. The stakes extend beyond Mars itself. NASA says that learning how the moons formed could clarify when Earth and the other inner planets may have acquired much of their water and organic compounds, which is a question about the origins of habitable worlds generally.
For now the practical milestone is simple. If the countdown holds, the probe departs on Monday afternoon on the U.S. East Coast and early Tuesday morning in Japan. Then comes roughly ten months of travel to Mars, a survey of both moons, and a wait of more than a year after arrival before sample collection can begin, with the capsule due home in 2031. Each stage has to succeed before the next one starts, which is why the launch is only the first of several make-or-break moments for the mission.
This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.
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