Japan launches historic Martian Moons eXploration spacecraft on a sample-return mission to Phobos.

Japan has launched the Martian Moons eXploration spacecraft on a historic sample-return mission to Mars and its two moons, Phobos and Deimos. The Japan Aerospace Exploration Agency-led mission lifted off on an H3 rocket from the Tanegashima Space Center.

If successful, the spacecraft will become the first to land on and return samples from Phobos to Earth. The 207-foot rocket carried the spacecraft on a nominal trajectory before separating its stages and boosters. The interplanetary transit will take about 10 months, with arrival scheduled for August 2027.

MMX will spend roughly three years in the Martian system. It will deploy a joint French-German rover named IDEFIX to the surface of Phobos in late 2028 or early 2029 and perform two touchdowns to collect soil samples. A return capsule will bring the materials down in Australia in 2031.

Scientists hope the samples will solve a decades-old mystery about whether Phobos and Deimos formed from a massive planetary impact or are captured asteroids from the early solar system. NASA is contributing scientific hardware, communications support, and $87 million in funding. In return, NASA will receive at least 15% of the returned Phobos sample for study at the Johnson Space Center.