Japan has launched its Martian Moons Exploration spacecraft on a high-risk mission to gather material from Phobos and bring it back to Earth in 2031. The project aims to turn a brief landing on Mars’s larger moon into evidence about the origin of the Martian system.

One account presents the mission chiefly as an “epic quest” to collect samples from a Mars moon, stressing the scale of the undertaking and the difficulty of reaching and operating on Phobos.¹ Another emphasizes its historic character: Jaxa says MMX is the first attempt to land on either Phobos or Deimos, despite decades of Mars missions by the United States and a Chinese landing in 2021.²

The spacecraft, launched aboard Japan’s H3 rocket from Tanegashima, is expected to reach Mars orbit next year. It is designed to return at least 10 grams of rock and soil after a short sampling operation on Phobos, while a French-German rover surveys potential landing sites. Five space agencies are collaborating on the mission.²

The scientific case is as important as the landing itself. Researchers are weighing two principal explanations for Phobos and Deimos: that they formed from debris after a major impact on Mars, or that they are asteroids captured by the planet’s gravity. Jaxa says distinguishing between those possibilities could help explain “how a habitable environment for life might have arisen on the terrestrial planets.”²

For mission partners, the return capsule would mark more than a technical first. “It is a once-in-a-lifetime chance,” said Markus Grebenstein, the German Space Agency’s rover chief, calling MMX the first sample-return mission from the Martian system.²