Japan is preparing to launch one of its most ambitious space missions, aiming to bring samples from a moon of Mars back to Earth for the first time. The Martian Moons eXploration (MMX) mission, led by the Japan Aerospace Exploration Agency (JAXA), is designed to investigate the origins of Mars’ two moons, Phobos and Deimos, and uncover clues about the early history of the solar system.
The spacecraft is scheduled to lift off aboard Japan’s H3 rocket from the Tanegashima Space Center at 4:41 a.m. Japan Standard Time on October 20, 2026. That corresponds to 3:41 p.m. EDT on October 19, or 1:56 a.m. Nepal time on October 20. According to JAXA’s latest launch announcement, the launch window includes backup dates beginning October 21. The spacecraft is expected to reach Mars in August 2027 and spend several years studying its moons before beginning its return journey.
The mission consists of three main spacecraft modules: propulsion, exploration and sample return. It also carries IDEFIX, a small rover developed jointly by France’s space agency, CNES, and the German Aerospace Center, DLR. The rover will examine the surface of Phobos, collecting information about its terrain, mineral composition and physical properties.
After arriving in the Martian system, MMX will observe Phobos from different altitudes and map potential landing locations. The mission plans to deploy IDEFIX during its surface exploration activities before attempting to collect samples. The rover is expected to reach Phobos in late 2028 or early 2029, while sample collection could begin as early as December 2028, according to details presented during a NASA mission briefing.
MMX will attempt two sample-collection landings on Phobos using a combination of coring and pneumatic sampling systems. The spacecraft aims to collect at least 10 grams of material and store it inside a return capsule. Once its primary work around Phobos is complete, the mission will also conduct flybys of Deimos, the smaller of Mars’ two moons, to gather additional scientific data.
The samples are expected to return to Earth in 2031, with the capsule targeting a landing in Australia’s Woomera region. Scientists will then be able to examine the material in laboratories using techniques that can reveal details far beyond the capabilities of instruments operating in space.
One of the mission’s biggest goals is to solve a long-standing mystery: how Phobos and Deimos formed. Scientists have two leading explanations. One suggests that the moons are asteroids captured by Mars’ gravity billions of years ago. The other proposes that a massive collision involving ancient Mars blasted material into orbit, eventually allowing the debris to form the two moons.
Both theories have supporting evidence, but neither has been conclusively established. The moons have characteristics similar to primitive asteroids, yet their nearly circular orbits around Mars are also consistent with a formation process involving debris from a major collision. Studying their composition could help scientists determine which explanation best fits the evidence.
To investigate these questions, MMX carries an array of scientific instruments developed by Japan and international partners. These include cameras for mapping the surface, an infrared spectrometer for identifying minerals and NASA’s MEGANE instrument, which will use gamma rays and neutrons to measure the elemental composition of Phobos.
MEGANE could help identify the presence of elements such as hydrogen, chlorine, sodium and potassium. Their abundance may provide clues about whether Phobos originated as an asteroid or formed from material involved in an ancient collision with Mars. Other instruments will examine surface temperatures, dust, charged particles and possible evidence of subsurface ice.
Scientists also hope the returned material could contain fragments of Mars itself. Ancient impacts may have blasted Martian rocks into space, with some eventually landing on Phobos. If such material is present, laboratory analysis could provide additional insights into the geological history of the Red Planet.
The mission is an international effort led by JAXA, with contributions from NASA, the European Space Agency, France’s CNES and Germany’s DLR. NASA has supplied the MEGANE instrument and a pneumatic sampling mechanism, while European partners have contributed to the rover and communications support. NASA is also expected to receive at least 15% of the returned samples for scientific study and long-term preservation.
If successful, MMX will mark a major milestone in planetary exploration by returning material from the Martian system to Earth. Beyond investigating the origins of Phobos and Deimos, the mission could improve scientists’ understanding of how planets and their moons evolved billions of years ago. Its technologies may also help prepare for future missions to Mars and other destinations in the solar system.
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Sources
- JAXA — Latest MMX launch schedule, October 18, 2026
- NASA — How MMX will investigate the origins of Mars’ moons, October 15, 2026
- JAXA — Official MMX mission website
- European Space Agency — MMX mission overview
