Japan Launches Historic MMX Sample-Return Mission to Mars’ Moon Phobos

October 20, 2026

Japan has successfully launched its Martian Moons eXploration (MMX) mission to study Mars’ two moons, Phobos and Deimos. Scheduled to arrive in August 2027, “MMX will become the first spacecraft to land on and return samples from Phobos for study back on Earth, which scientists think could shed light on a decades-old mystery about the moons’ origins” and resolve whether they were formed from a giant impact or were captured asteroids, reports Space.com. From the report: It was the 10th liftoff of Japan’s expendable, two-stage H3 rocket, which was jointly developed by JAXA and Mitsubishi Heavy Industries. After clearing its launch pad today, the 207-foot-tall (63 meters) launch vehicle flew a nominal trajectory through its ascent corridor over the Pacific Ocean, jettisoning its four solid boosters in pairs just before the flight clock reached two minutes. The rocket shed its payload fairings about one minute and 20 seconds later, exposing MMX to the vacuum of space for the first time. […] MMX is now under its own power, and on course for Mars.

The interplanetary transit will last about 10 months, with the spacecraft scheduled to arrive at the Red Planet in August 2027. When it does, MMX’s propulsion module will execute an orbital insertion burn to place itself in a quasi-satellite orbit (QSO) around Phobos, which places MMX within the space around the moon as both circle Mars. MMX will spend about three years in the Martian system, devoting much of that time to studying the 14-mile-wide (22 km) Phobos with its science instruments. The spacecraft also carries the IDEFIX rover, a joint effort of the space agencies of France and Germany, which is scheduled to deploy to the surface of Phobos in late 2028 or early 2029.

After a mapping campaign to select suitable landing sites, MMX will perform two separate touchdowns on Phobos to collect and stow samples in the spacecraft’s return capsule. Following its second landing and sample collection, MMX will briefly return to QSO with Phobos before transferring to a more elongated orbit around Mars that intersects with the planet’s smaller moon, Deimos, which is just 8 miles (14 km) in diameter. During the last several months of its time around Mars, MMX will perform a series of Deimos flybys before departing for Earth in November 2030. If all goes according to plan, the MMX sample-return capsule will land in Australia in 2031. You can watch a recording of the launch on YouTube.