Japan's space agency launched its Martian Moons eXploration (MMX) mission on Monday, sending a spacecraft on a roughly six-year round trip that aims to make it the first ever to land on Mars's moon Phobos and bring a sample of it back to Earth.
The spacecraft lifted off from Tanegashima Space Center aboard an H3 rocket at 3:41pm EDT (4:41am local time the following day in Japan). MMX is targeting at least 10 grams of material collected from a depth of two centimeters or more beneath Phobos's surface — a sampling approach designed to retrieve material less altered by space weathering than loose surface dust.
A six-year journey with one central mystery to solve
According to mission timelines published by JAXA and the European Space Agency, MMX will arrive at Mars in August 2027 and enter orbit around Phobos the following month, before its return capsule is scheduled to land in Woomera, South Australia, in 2031. A French-German rover named Idefix, weighing about 55 pounds, will be deployed to study the moon's surface directly.
The mission's central scientific question is one planetary scientists have debated for decades: whether Phobos formed from debris thrown up by a massive asteroid or comet impact on Mars, or whether it is a captured asteroid that was gravitationally pulled into orbit around the planet. The two origin stories would leave very different chemical and mineralogical fingerprints, which is precisely what a returned sample — rather than remote observation alone — is positioned to resolve.
MMX will be the first spacecraft to both land on Phobos and return a sample of it to Earth for study.
Mission description via Space.com
A mission years in the making
MMX was originally slated to launch in 2024, and JAXA has confirmed the roughly two-year delay was tied in part to testing of the H3 rocket, which suffered a high-profile failure on its debut flight in 2023 before returning to service. Monday's successful launch clears the biggest near-term hurdle for a mission that, if successful, would add Japan to a short list of space agencies that have returned samples from beyond the Moon.
What happens next
Mission controllers now face a long, largely quiet cruise phase before MMX reaches Mars orbit next year, followed by a technically demanding landing on a moon whose weak gravity and irregular shape make touchdown far more delicate than landing on a planet. Scientists say even a successful landing and sample collection will leave the public waiting years for the payoff: the sample itself will not reach Earth until 2031.