Japan's space agency successfully launched its most ambitious planetary mission to date early Tuesday, sending a spacecraft on a roughly five-year round trip to land on Phobos, one of Mars' two small moons, scoop up surface material, and haul it back to Earth — a feat no country has ever pulled off.

The Martian Moons eXploration (MMX) probe lifted off atop an H3 rocket at 4:41 a.m. local time from the Tanegashima Space Center, with liftoff confirmed by the Japan Aerospace Exploration Agency (JAXA). About 71 minutes after launch, controllers confirmed the spacecraft had separated cleanly and been placed into its planned trajectory. "We have confirmed that the probe is in a stable condition," JAXA's mission leader said, according to Space.com's coverage of the launch.

Three Consecutive Successes

The launch was also a milestone for the H3 rocket itself, which failed its debut flight in 2023. Tuesday's mission was the vehicle's third straight success, pushing its overall track record to roughly 80%, the Japan Times reported, citing Jiji Press.

MMX is expected to reach Mars orbit in roughly a year, where it will spend time studying both Phobos and its smaller sibling moon, Deimos, before attempting a landing on Phobos around 2030. Once down, the spacecraft aims to collect at least 10 grams of surface material — enough, scientists hope, to settle a long-running debate over whether Phobos is a captured asteroid or debris blasted off Mars by an ancient impact. A roughly 25-kilogram rover named IDEFIX, built by France's CNES and Germany's DLR, will also be deployed onto the moon's surface to scout the terrain.

"THE FIRST SPACECRAFT EVER TO LAND ON PHOBOS AND BRING A SAMPLE BACK TO EARTH."

The mission is a genuinely international affair: NASA, France's CNES, Germany's DLR and the European Space Agency are all contributing instruments or hardware, with ESA calling the H3's performance a strong showing for Japan's newest heavy-lift rocket. The sample capsule isn't expected to parachute back down to Earth until 2031, meaning the mission that just launched won't actually deliver its payload for another five years.

For now, mission controllers are focused on checking out the spacecraft's systems during the long cruise to Mars — the first of many milestones on a mission that, if it goes to plan, will answer a question about the solar system's history that's gone unresolved since Phobos was first spotted orbiting Mars 150 years ago.