The $578 million mission will investigate how Phobos and Deimos formed
Japan launched a spacecraft towards Mars on Tuesday on a historic five-year mission to explore the Red Planet’s mysterious moons, Phobos and Deimos, and bring back samples to Earth.
Led by the Japan Aerospace Exploration Agency (JAXA), the mission aims to collect at least 10 grams of material from Phobos, marking the first attempt to retrieve samples from the Martian sphere.The spacecraft lifted off before dawn from Tanegashima Island, Japan’s main spaceport, as five space agencies joined forces for the ambitious project. If successful, the mission, known as Martian Moons Exploration (MMX), will deliver dust, soil and rock samples from Phobos to Earth in 2031, potentially offering new insights into the origins of Mars’ moons and the evolution of the Solar System.
Despite decades of Mars exploration, no spacecraft has ever landed on either Phobos or Deimos, the planet’s two small moons. While the United States and China have successfully landed spacecraft on Mars, retrieving samples from the planet or its moons remains an unaccomplished feat. Japan, however, enters the mission with experience from two successful asteroid sample-return missions.
Why Japan is targeting Mars’ moons
The $578 million mission will investigate how Phobos and Deimos formed, addressing a long-standing debate in planetary science.
One theory suggests the moons emerged from debris scattered into orbit after a massive object collided with Mars. Another proposes that they are asteroids captured by the planet’s gravitational pull.Phobos, the larger and closer of the two moons, is an irregular, potato-shaped object measuring about 22 kilometres across. Scientists believe its surface material could preserve clues about the early history of the Martian system and the processes that shaped the planet.By studying samples collected from Phobos alongside observations of Deimos and Mars, researchers hope to understand how planetary bodies formed and how materials such as water and organic compounds were transported across the Solar System. The mission will also examine Mars’ atmosphere and the surrounding space environment to investigate how atmospheric material escapes into space.
Rover deployment and sample return
The five-tonne MMX spacecraft is expected to reach the Martian system in late summer 2027.
It will study the two moons before deploying a French-German rover, named Idefix after the white terrier in the Asterix comics, to the surface of Phobos.The spacecraft will then attempt to collect at least 10 grams of surface material before beginning its return journey to Earth. The mission is expected to last approximately five years, with the samples scheduled to arrive in 2031.Beyond its scientific objectives, MMX will test technologies needed for future exploration of Mars, including landing operations on small celestial bodies, advanced sampling systems and long-distance communications. With communication delays of up to 44 minutes for a round trip, the spacecraft must operate with considerable autonomy.