Japan and NASA Launch MMX Mission to Bring Mars Moon Soil Home

A round trip to Mars to solve a moon mystery

Lifting off from the Tanegashima Space Center in Japan, the Martian Moons eXploration (MMX) mission begins an ambitious five-year trek to Mars and back. Instead of touching down on the Martian surface like conventional rovers, the spacecraft will spend its operational life surveying both Deimos and Phobos before attempting a landing on Phobos to retrieve pristine surface material.

Astronomers have argued for decades about where Mars got its tiny, lumpy satellites. One camp believes Phobos and Deimos are ancient asteroids snagged by Mars' gravitational pull as they drifted past. The other suggests a colossal collision battered early Mars, hurling debris into orbit that fused into moons—mirroring the prevailing theory of how Earth's own moon formed. Analyzing the physical chemical makeup of Phobos will give scientists a definitive answer.

Knowing how these moons formed will also help researchers understand when and how inner rocky planets gathered water and organic compounds, shedding light on the broader evolution of planetary systems like those studied when astronomers find exotic remnants around distant stars.

MMX Mars mission timeline and hardware specs

NASA's hardware role in the MMX Mars mission

While JAXA leads the project, NASA supplied critical scientific and collection hardware. The agency's primary scientific instrument on board is Megane—the Mars-moon Exploration with Gamma rays and Neutrons spectrograph—which will map the elemental composition of Phobos from orbit.

To actually bag the dirt, NASA developed a pneumatic sampler, or p-sampler, designed to puff gas into the regolith to push loose particles directly into a collection canister. NASA's Deep Space Network will handle long-range tracking, navigation, and communications across the millions of miles between Earth and Mars throughout the mission's lifespan.

The tight race to bring Mars soil home

Navigating a spacecraft to Mars, making a soft landing on a low-gravity body, and launching back to Earth is a feat that has never been accomplished. JAXA has experience bringing space rock home after its successful Hayabusa missions to asteroids, and NASA retrieved dust from Bennu via Osiris-Rex in 2023. Yet the Martian gravity well poses an entirely different challenge.

JAXA plans for MMX to reach Mars in August 2027. After spending roughly three years conducting science and gathering soil, the probe is scheduled to fire its departure engines in November 2030, arriving back on Earth in July 2031.

The timeline puts JAXA and NASA in a close race with China. The China National Space Administration plans to launch its own sample-return mission, Tianwen-3, in 2028, targeting a direct return from the surface of Mars in 2031. Whichever succeeds first will capture a major milestone in deep-space exploration.

Availability and international science access

The MMX mission is an international scientific partnership funded by the Japanese and US space agencies. While the spacecraft itself was developed and launched in Japan, the eventual samples returned in 2031 will be split between Japanese and American research institutions, with aliquots made available to international peer-review teams across the US, UK, and Europe after initial curation.