Mars' Mysterious Moons: How the MMX Mission Will Unlock Their Secrets

Updated: March 17 2025 12:56
In the vast expanse of our solar system, Mars has long captured our imagination. But while the Red Planet itself has been extensively studied, its two small moons—Phobos and Deimos—remain largely enigmatic. That's about to change with the ambitious Martian Moons eXploration (MMX) mission, which promises to revolutionize our understanding of these celestial bodies.



Phobos and Deimos have puzzled scientists since their discovery in 1877. Despite numerous orbiter missions capturing images from a distance, no spacecraft has ever landed on either moon. The fundamental questions remain unanswered: How did these moons form? What are they made of? Are they captured asteroids, or did they form from debris ejected when something massive struck Mars billions of years ago?


These questions aren't just academic curiosities. Understanding the origin of Mars' moons could provide crucial insights into how our solar system formed and evolved, and might even help us piece together the history of Mars itself.


Scheduled for launch in 2026 from Japan's Tanegashima Space Center, the MMX mission represents an impressive international collaboration. Led by the Japanese space agency JAXA, the mission includes significant contributions from Germany's DLR and France's CNES space agencies.


After approximately one year of interplanetary travel, the MMX spacecraft will reach Mars orbit in 2027. From there, it will conduct comprehensive studies of both Phobos and Deimos using eight scientific instruments. But the most exciting aspects of the mission will come in early 2029, when two unprecedented events will occur, the release of the IDEFIX rover onto Phobos and the collection of surface samples from Phobos for return to Earth.



One of the most fascinating components of the MMX mission is the Franco-German rover named IDEFIX (a nod to the small dog character from the Asterix comic series). This plucky explorer faces an extraordinary challenge: navigating the surface of Phobos, which has gravity less than 1/1000th that of Earth.
IDEFIX isn't just adorably named—it's packed with cutting-edge technology:

• A carbon-fiber reinforced structure built by DLR
• A sophisticated autonomous navigation system for traversing Phobos' surface
• The miniRAD radiometer for thermal measurements
• The RAX Raman spectrometer for mineralogical analysis
• Camera systems for orientation and exploration
• Systems to study the mechanical properties of Phobos' surface

What makes IDEFIX particularly impressive is its ability to operate in an environment where traditional rover designs would simply float away. The team has developed specialized locomotion and uprighting systems that will allow IDEFIX to move effectively despite the moon's extremely low gravity.



Perhaps the most ambitious aspect of the MMX mission is its sample return component. The mothership will briefly land on Phobos to collect several grams of surface material, which will then be sealed in a return capsule. If all goes according to plan, these precious samples will arrive on Earth in 2031, ready for detailed analysis in specialized laboratories.


This wouldn't be JAXA's first successful sample return mission. In 2020, their Hayabusa2 spacecraft successfully delivered material from asteroid Ryugu back to Earth—a mission that also featured contributions from DLR and CNES.



You might wonder why space agencies would invest so heavily in studying two small, seemingly unremarkable moons. The answer lies in what scientists call "small body science." Small objects like Phobos and Deimos preserve information about the early solar system that larger bodies have lost through geological processes.

If Phobos and Deimos are captured asteroids, they could contain pristine material from the outer solar system. If they formed from Mars impact debris, they might contain ancient Martian material. Either way, they represent scientific treasure troves that could help answer fundamental questions about our cosmic neighborhood.

Furthermore, Phobos in particular has been proposed as a potential staging location for future human exploration of Mars. Its weak gravity makes it easier to land on and depart from than Mars itself, potentially making it a valuable waypoint for future crewed missions.


The MMX mission's journey spans nearly a decade from launch to completion:

1. 2026: Launch from Tanegashima Space Center aboard an H-3 rocket
2. 2027: Arrival at Mars, beginning orbital observations of both moons
3. Early 2029: IDEFIX rover deployment to Phobos surface for a three-month exploration phase
4. Later in 2029: Sample collection from Phobos
5. 2031: Sample return capsule arrives on Earth

This extended timeline reflects the complexity of the mission and the careful planning required to execute it successfully.


The MMX mission exemplifies how international collaboration enables ambitious space exploration. JAXA provides the main spacecraft and mission architecture, while DLR and CNES contribute the sophisticated IDEFIX rover. Eight DLR institutes across five locations in Germany are working on different aspects of the rover, showing the distributed, collaborative nature of modern space engineering.

Once the mission launches, operations will be coordinated between control centers in Japan, Germany, and France—a truly global effort to unlock the secrets of these mysterious moons. The mysteries of Phobos and Deimos have persisted for nearly 150 years since their discovery, but soon, thanks to MMX, we may finally have answers to some of our most fundamental questions about these enigmatic moons of Mars.