Japan's MMX Mission Set to Launch, Aiming to Retrieve Martian Moon Sample

The Mars Moons Exploration (MMX) mission, led by the Japanese Space Agency (JAXA), is scheduled to launch on October 20 to collect a sample from Phobos, one of Mars's moons, and bring it back to Earth. If successful, it will mark the first time a sample from Mars or its moons has been returned for laboratory analysis on Earth.

The spacecraft is expected to reach Phobos in August 2027. Scientists hope the mission will help solve the long-standing mystery of how Mars's two moons, Phobos and Deimos, formed. These moons are small and irregularly shaped, with Phobos measuring about 20 km (12 miles) across and Deimos about 10 km (six miles) across.

The MMX spacecraft will first study Deimos before focusing on Phobos. A small rover will be deployed to explore Phobos's terrain. Professor Sara Russell from the Natural History Museum, deputy for sample analysis on the MMX mission, described the mission as "incredibly ambitious and fun," noting the unique challenge of landing a rover on a moon with very little gravity, which is further complicated by the gravitational pull of Mars.

Following the rover's exploration, the MMX spacecraft will land on Phobos to collect a dust sample using a robotic arm. Approximately 10 grams of material will be collected and stored in a capsule for return to Earth, with a planned landing in South Australia in 2031. Dr. Chrysa Avdellidou, from Leicester University, emphasized that even small sample amounts are scientifically valuable.

The origin of Phobos and Deimos remains a subject of debate. Two primary hypotheses suggest they either formed from debris after a large impact on early Mars or are captured asteroids from the outer solar system. Analysis of the returned sample's chemistry and mineral composition is expected to clarify which theory is correct.

There is also a possibility that the sample could contain dust from Mars itself. Because Phobos orbits so close to Mars, impacts on the Martian surface can eject material that may land on Phobos. Such a discovery would provide direct insights into the composition and history of Mars.

This mission comes at a time when other sample return efforts face challenges. NASA's Mars Sample Return mission has had its funding halted by the US Congress, and while China plans its own Mars sample return mission for 2028, Japan's MMX mission is currently the most immediate effort to bring Martian material back to Earth. While Martian meteorites exist on Earth, they are rare and become contaminated upon atmospheric entry, making pristine samples from direct missions highly sought after by scientists.

The MMX mission is set to launch from the Tanegashima Space Center at 04:41 local time on October 20 (20:41 BST on October 19).