Japan launches historic mission to collect samples from Martian moon Phobos

Japan's space agency sent a rocket skyward from Tanegashima this morning carrying a spacecraft designed to do something no mission has attempted before: land on Mars's moon Phobos, collect material from its surface, and bring it home. The Martian Moons eXploration mission, or MMX, is a five-year undertaking that will culminate with samples landing in the Australian outback—specifically at Woomera in remote South Australia—sometime around 2031.

The MMX spacecraft will spend the next year traveling through space before arriving at Mars in 2027. Once there, it will settle into orbit around Phobos, the smaller and closer of Mars's two moons, a body so small and irregularly shaped that scientists describe it as potato-like. The spacecraft will then attempt two separate landings, each time deploying a rover to the surface to collect at least 10 grams of sand from a depth of roughly two centimeters. This sounds straightforward until you consider the obstacle that makes Phobos uniquely challenging: its gravity is extraordinarily weak. Yaji Kentaro, part of the MMX project team, explained that this extreme weakness is precisely why collecting samples from the moon is so difficult. To compensate, engineers designed the rover's landing legs with special features intended to lock it firmly in place during touchdown and sample retrieval.

The scientific reasoning behind targeting Phobos rather than Mars itself is compelling. Mars's gravity is strong enough to make landing and collecting samples from the planet's surface extremely difficult. Phobos, by contrast, has remained geologically unchanged in ways that Mars has not. The moon has not undergone the same evolutionary processes as planets, which means it should preserve evidence of the early solar system—a kind of time capsule from when Mars and its moons were forming. Scientists want to understand where water and organic materials came from, questions that matter not just for understanding Mars but for understanding how habitable worlds form anywhere. There are competing theories about Phobos's origin: either it was created by a massive collision with Mars, or it began as an asteroid that Mars's gravity eventually captured. The samples and observations from MMX should help settle this question.

Mars itself holds tantalizing clues. The planet is now a cold desert with a thin atmosphere, but evidence suggests it once resembled Earth. Traces of water exist on its surface, and scientists have speculated that life could have emerged there. Understanding how Mars formed and what conditions it once had could illuminate the broader question of how planets become habitable—and whether life might have taken hold elsewhere in the solar system. Phobos, having preserved its early character, offers a window into that ancient Martian environment.

After collecting samples from Phobos, the MMX spacecraft will observe Mars's second moon, Deimos, before beginning its year-long journey back to Earth. When it arrives, a re-entry capsule will separate from the spacecraft and descend through Earth's atmosphere, carrying the sand and rock samples collected from an alien moon. That capsule will touch down at Woomera, where Australian scientists and international partners will retrieve and study material that has never before been in human hands.

The launch drew international attention. Australia's ambassador to Japan, Andrew Shearer, traveled to Tanegashima to witness the rocket's departure, alongside ambassadors from France and Germany, a deputy ambassador from the United States, and representatives from space agencies including NASA. The presence of these dignitaries underscored that MMX is not solely a Japanese endeavor but a collaborative effort with global implications. For Australia, the role is concrete: the country will serve as the landing site for humanity's first samples from a Martian moon, positioning it as a key player in one of space exploration's most ambitious scientific undertakings.