Japan is preparing for one of its most ambitious planetary exploration missions, targeting the mysterious moons of Mars. Through the Martian Moons eXploration (MMX) mission, the Japan Aerospace Exploration Agency (JAXA) aims to explore Mars’ two small moons, Phobos and Deimos, with particular attention to Phobos. The mission is designed not only to observe these distant worlds but also to collect samples from the surface of Phobos and bring them back to Earth for detailed scientific analysis.
The mission represents an important step in Japan’s growing role in deep-space exploration. Scientists believe that studying the Martian moons could help answer fundamental questions about the origins of Mars, its moons, and even the early Solar System.
A Mission Focused on Phobos
Mars has two known moons, Phobos and Deimos. Both are much smaller than Earth’s Moon and have irregular shapes. Among them, Phobos is the main target of Japan’s MMX mission.
The spacecraft is expected to travel to the Martian system, enter orbit around Mars, and conduct detailed observations of both moons. After studying Phobos from orbit, the spacecraft will attempt to approach its surface and collect material.
The samples are particularly important because scientists can study material returned to Earth using advanced laboratory equipment. Instead of relying only on instruments aboard a spacecraft, researchers will be able to examine the samples in laboratories for years or even decades.
Why Are Mars’ Moons Important?
One of the biggest mysteries surrounding Phobos and Deimos is their origin.
Scientists have proposed several theories. One possibility is that the moons are asteroids that were captured by Mars’ gravity long ago. Another theory suggests that they were created from material thrown into space after a massive impact on Mars.
Determining which explanation is correct could significantly improve our understanding of Mars and its history.
If Phobos turns out to contain material similar to asteroids, it could support the idea that the moon was captured by Mars. If its composition is more closely related to Mars, it could strengthen the impact-origin theory.
This is why bringing samples back to Earth is such an important part of the MMX mission.
Exploring Both Phobos and Deimos
Although Phobos is the primary target, MMX will also study Deimos. Observations of both moons could allow scientists to compare their surfaces, compositions, shapes, and environments.
Deimos is farther from Mars than Phobos and has a different orbital relationship with the planet. By examining both moons, researchers hope to understand whether they share a common origin or developed through different processes.
The spacecraft will also observe Mars itself from the Martian system. This will provide additional scientific information about the planet and its surrounding environment.
A Challenging Journey
Reaching the moons of Mars is far more difficult than simply traveling to Mars. The spacecraft must carefully navigate through the gravitational environment of the Mars system and operate around small objects whose gravity is extremely weak.
Phobos is also a challenging landing target. Its irregular shape, rocky surface, low gravity, and uncertain terrain make close operations technically demanding.
The spacecraft must approach Phobos at carefully controlled speeds and positions. Even a small navigation error could make landing or sample collection difficult.
JAXA has extensive experience with challenging sample-return missions. Japan’s Hayabusa and Hayabusa2 missions successfully demonstrated the ability to visit small celestial bodies, collect material, and return samples to Earth. The experience gained from those missions is expected to be valuable for MMX.
The Idefix Rover
A major feature of the MMX mission is the participation of an international team developing a small rover known as Idefix.
The rover is designed to operate on the surface of Phobos and gather information about its terrain and physical properties. It will support the mission by providing close-up observations that a spacecraft in orbit cannot easily obtain.
Operating a rover on Phobos will be an extraordinary technical achievement. Because Phobos has extremely low gravity, movement across its surface will be very different from driving a rover on Earth or even Mars.
The rover must be designed to remain stable while moving across uneven terrain. Its observations could provide valuable information about the structure and properties of the moon’s surface.
Collecting Samples From Phobos
The most exciting part of the mission is the planned sample return.
MMX is intended to collect material from Phobos and store it safely inside the spacecraft. After completing its exploration activities, the spacecraft will begin the long journey back toward Earth.
When the samples arrive, scientists will have an opportunity to study them in unprecedented detail.
Laboratories can examine minerals, chemical compositions, microscopic structures, and other properties that may reveal how Phobos formed. Researchers can also compare the material with meteorites, asteroid samples, and Martian material already studied on Earth.
The results could help scientists understand the history of the Martian system and the processes that shaped the inner Solar System billions of years ago.
International Cooperation
Although MMX is a Japanese-led mission, it involves international cooperation. Scientists and engineers from several countries are contributing to different aspects of the project.
International cooperation is increasingly important in planetary exploration because modern missions require expertise in spacecraft engineering, robotics, planetary science, communications, navigation, and sample preservation.
The participation of international partners also means that the scientific results from MMX could benefit researchers around the world.
A New Chapter in Mars Exploration
Mars has been explored by numerous orbiters, landers, and rovers, but its moons have received far less attention. MMX could therefore open a new chapter in Martian exploration.
Studying Phobos may also have practical importance for future missions to Mars. Understanding the environment around the planet could help scientists and engineers plan future robotic or crewed exploration.
Phobos has sometimes been discussed as a possible location for future exploration missions because reaching its surface could require less energy than landing directly on Mars. While such possibilities remain part of long-term planning, detailed scientific information about Phobos would be valuable for future mission designers.
Looking Toward the Future
Japan’s MMX mission demonstrates how planetary exploration is moving beyond simply taking photographs of distant worlds. Modern missions increasingly seek to bring physical samples home so scientists can conduct detailed investigations on Earth.
The planned exploration of Phobos and Deimos could provide answers to questions that have remained unresolved for decades. Where did these moons come from? What are they made of? How did they become part of the Martian system? And what can they tell us about the early history of the Solar System?
The answers may come from tiny grains of material collected millions of kilometers from Earth.
Japan’s effort to reach the moons of Mars is therefore much more than a spacecraft mission. It is an attempt to unlock the history of an entire planetary system.
If successful, MMX could become one of the most significant achievements in robotic planetary exploration, demonstrating Japan’s technological capabilities while providing scientists with an extraordinary new source of information about Mars and its mysterious moons.
As humanity prepares for a future of deeper exploration of Mars and beyond, missions such as MMX will play an important role. The journey to Phobos and Deimos may help transform two little-known moons into valuable scientific windows into the history of our cosmic neighborhood.
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