MISSION
The unexplored frontier: Mars’s moon Phobos
Mars bears traces of past water, and suggestions that life once emerged on the planet. The Martian moons, Phobos and Deimos, are expected to hold many clues to the formation of the Solar System, and the transport of materials around our Sun.
Mission overview
Returning 10g of material from the Martian moons to Earth
MMX is a mission designed to conduct a sample return operation: travelling to a celestial body, conducting detailed observations, collecting surface material (grains and rock samples), and bringing the sample back to Earth. Building on the experience gained through the successful Hayabusa2 mission to an asteroid, MMX will visit the Martian moon Phobos. The mission is scheduled to launch in fiscal year 2026 and span approximately five years as the spacecraft travels to the Martian system and back, conducts detailed observations of the two moons, collects a minimum of 10g of sample from Phobos, and returns the sample to Earth, marking the world's first sample return mission from the Martian sphere.
Mission profile
Five years of challenges
Approximately one year after launch, MMX will arrive in the vicinity of Mars. The spacecraft is then scheduled to enter an orbit that flies close to the Martian moon (Quasi-Satellite Orbit or QSO) to conduct detailed observations of Phobos.
After completing both observations and sample collection, the spacecraft will return to Earth over the course of about one year to deliver the samples home.
Launch
Launched from Tanegashima Space Center in Japan, aboard the H3 launch vehicle.
1 year journey to the Mars sphere
Upon entering Mars orbit, the MMX spacecraft will follow an orbital path similar to that of Phobos (a quasi-satellite orbit). In addition to Phobos and Mars, MMX will also observe Deimos from a distance.
Observations in a Quasi-Satellite Orbit (QSO) around Phobos
Explore the global shape of Phobos, and observe dozens of candidate landing sites.
Observations from the Quasi-Satellite Orbit (QSO) around Phobos
Candidate landing sites on Phobos can be observed in detail to determine the best landing location. Investigations will include the topology, spectroscopy, chemical composition of the sites.
Observations from the Quasi-Satellite Orbit (QSO) around Phobos
Two landings: one for the rover, one for the main spacecraft
Observations conducted during the descent to the landing site, the landing itself, and the ascent.
The rover will land before the spacecraft, and observe the Phobos surface.
After this, the main spacecraft will land itself and collect 10g of sample material.
Observations from the Quasi-Satellite Orbit (QSO) around Phobos
Conduct scientific observations of Phobos and, if possible, attempt polar observations by tilting the QSO orbital plane.
Conduct Deimos flyby
Attempt observations of Deimos.
Depart the Mars sphere
Igniting the main engines, the spacecraft will escape from the Mars sphere in a single manoeuvre. The course is set for Earth; a journey that will take one year.
Return to Earth
The sample capsule will separate from the spacecraft and enter the Earth's atmosphere. Recovery is scheduled to be in Australia.
- DEIMOS — Image credit: NASA/JPL
- PHOBOS — Image credit: NASA/JPL-Caltech/University of Arizona
- Mars — Image credit: NASA
- Earth — Image credit: NASA Goddard Space Flight Center / Reto Stöckli
Mission objectives
Why target the moons of Mars?
Mars is a planet that shares many similarities with Earth, yet today it has only a thin atmosphere and a cold environment. To unravel the mystery of how Mars evolved into its present state, scientists would ideally study Mars itself. However, the planet's strong gravity presents significant technical challenges for landing and sample return missions. For this reason, MMX has selected Phobos, one of Mars's moons, as the exploration target. As a small body that is thought to have undergone little change over time, Phobos should preserve valuable information about the history and evolution of the Martian sphere. By investigating Phobos, MMX will address important scientific questions while also advancing the technologies needed for future exploration of Mars.
MISSION 01Planetary science
Investigating the origins of the Martian moons and uncovering the evolutionary history of the Mars sphere
By studying Mars, Phobos and Deimos, the MMX mission seeks to understand planetary formation in the Solar System, and how material essential for habitability and the emergence of life, such as water and organics, were transported through the system.
MISSION 02Development of exploration technology
The foundations for future space exploration
The MMX mission aims to develop technology that will pave the way for the next generation of space exploration, including round-trip travel to the Martian sphere, landing and operations on the surface of a celestial body, advanced sampling capabilities, and long-distance communication.
Mission outcomes
Unlocking the mysteries of the Solar System through the grains of Mars's moons!
Understanding how Mars and the two moons formed is a heavily debated topic in theories on the formation of our Solar System. Two main hypotheses exist concerning the origin of the Martian moons. The "giant impact hypothesis" postulates that the moons formed after a massive collision between a celestial body and Mars, which scattered debris into orbit that coalesced into the moons. Meanwhile, the "capture hypothesis" suggests that the moons are asteroids from the outer Solar System that were captured by Mars's gravity. Remote-sensing observations by the MMX spacecraft and the detailed analyses of the returned sample will clarify the moons' origin.
Observations of Mars, the planet's atmosphere and the space environment in the vicinity of the moons will explore how atmospheric material circulates and escapes into space, providing insights into the processes that shaped Mars's long-term evolution.
Together, these results will tackle one of the central questions in planetary science: how environments capable of supporting the prebiotic chemistry necessary for the emergence and persistence of habitable conditions arose in the Solar System.
Mission expectations
World-leading small body exploration and sample return technology
Through the Hayabusa and Hayabusa2 missions, Japan cultivated technology for landing on small celestial bodies and collecting samples. MMX will develop this technology for the Martian moons, bridging the gap between asteroid and Mars exploration. The challenge of the round-trip journey to the Mars sphere and the advanced sampling operations will refine Japan's specialisation and pioneer technology that will pave the way for future Mars exploration and sample return missions.
Features of the MMX spacecraft
10 spacecraft components that support the mission
The MMX mission entails numerous challenges: a long-duration spanning approximately five years, the unexplored surface of Phobos, a communication time lag of up to 44 minutes (round-trip), a gravitational environment distinct from that of Earth or our Moon, limited propellant, and the extreme temperature fluctuations in space. Amidst these conditions, the spacecraft must conduct observations, execute a landing, collect over 10 grams of samples, and return to Earth. Let’s examine the mechanisms and innovative design features of the spacecraft through ten of its key components.
At launch
Exploration module
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Return module
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Propulsion module
Mars orbit insertion
Exploration module
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Return module
Earth return
Return module
Securing the power supply
A stable power supply is essential for long-duration space travel and observation. Solar energy is converted into electricity to power the spacecraft's various systems and scientific instruments. Our electrical power subsystem constantly tracks the Sun to ensure that the largest possible surface area of the solar paddles are exposed to sunlight.
Explanation of the spacecraft
Mission Subsystem
The various different instruments to measure scientific data.
Data handling Subsystem
The data obtained from mission instruments and the spacecraft bus system is processed here to transmit to Earth. At the same time, data that cannot be downlinked is recorded in the Retrive Data Recorder (RDR) installed on the Sample Return Capsule.
Electrical Power Subsystem
Generates, stores, and provides electrical power to the whole spacecraft.
Guidance, Navigation and Control Subsystem
Controls the attitude of the spacecraft and maintains knowledge of where the spacecraft is located.
Attitude and Orbit Control Subsystem
By using sensors and actuators such as thrusters and gyroscopes, this controls the spacecraft’s orbit and attitude.
Landing Subsystem
Consists of the landing gear and all other necessary devices to land the Martin moon surface safely.
Thermal Control Subsystem
Maintains thermal conditions for all devices and instruments.
Communication Subsystem
Provides communication functions between spacecraft and the control center.
Structure Subsystem
Provides structural support to the propulsion module, exploration module, return module, and all onboard devices and instruments.
Propulsion Subsystem
Responsible for the chemical propulsion system used to accelerate, deaccelerate and control attitude.
Sampler
Sampler : collects samples from the Martian moon.
Sample Return Capsule: responsible for bringing samples taken from the Martian moon safely back to the Earth.
Ground System
Consists of ground facilities such as antennas to operate the spacecraft via sending commands and receiving measurement data.