Japan is set to launch a pioneering space mission to collect samples from Phobos, one of the two small moons orbiting Mars. The mission, known as Martian Moons eXploration (MMX), is scheduled to lift off from the Tanegashima Space Center early Tuesday aboard a Japanese H3 rocket. The endeavor marks the first attempt to retrieve samples from a Martian moon and return them to Earth.
The spacecraft is expected to take around one year to reach Mars, arriving in the region by August 2027. Upon arrival, it will spend up to three years orbiting Phobos, conducting scientific observations, and preparing for a landing. The mission includes plans to collect surface and subsurface soil samples from the moon, before beginning the journey back to Earth with the material in 2031.
Phobos and its smaller counterpart, Deimos, remain largely unexplored despite decades of Mars missions. Multiple Russian attempts to land on Phobos, including a 2011 effort, failed to succeed. Phobos measures approximately 27 kilometers in diameter and orbits Mars three times a day at about 6,000 kilometers above the planet’s surface.
Understanding the formation and composition of these moons is a central goal of MMX. Scientists debate whether Phobos and Deimos are debris from a massive impact on Mars or captured asteroids from elsewhere in the solar system. Researchers also hope the samples will shed light on the origins of life and early solar system processes. According to Kiyoshi Kuramoto, the mission’s principal investigator, analysis of Phobos soil could provide definitive answers, as material from Mars itself may constitute about 0.1% of the collected samples.
The mission is a collaborative effort, with equipment and support contributed by NASA, the European Space Agency, and other international partners. Among the 13 scientific instruments aboard MMX is a small rover named Idefix, developed jointly by French and German teams. Idefix will be the first rover to land on a Martian moon, planned to operate for roughly 100 days on Phobos’ surface to conduct remote sensing and assist in identifying suitable sampling sites.
Sample collection will involve two separate attempts using different methods: a NASA-designed device that employs pressurized gas to gather surface dust, and a Japanese coring tool designed to extract material from beneath the surface, approximately two centimeters deep. Collecting samples from multiple locations enhances the chance of retrieving scientifically valuable material, including any potential signs of past microbial life related to Mars.
Phobos' extremely low gravity, just a fraction of Earth's, presents technical challenges for landing and sample collection. To address this, the spacecraft is equipped with shock-absorbing landing gear with four legs, designed to minimize bouncing. The rover’s wheels are engineered for traction in low gravity and can right themselves if tipped over.
Once samples are secured, they will be stored in a heat-resistant capsule capable of surviving reentry through Earth’s atmosphere. The return module is projected to land in Australia before the collected material is transported to Japan for analysis.
The MMX mission also serves broader objectives by providing data that may inform plans for future human missions to Mars. Project manager Yasuhiro Kawakatsu emphasized the potential significance of Martian moons as bases for crewed exploration, noting that the U.S., China, and other nations have expressed ambitions to send astronauts to the Red Planet.
The mission underscores growing international interest in Mars exploration, coinciding with renewed efforts by multiple countries to advance human and robotic spaceflight beyond the Moon. The insights gleaned from Phobos could contribute valuable knowledge for overcoming the logistical challenges of interplanetary travel and establishing a sustainable human presence on Mars.