TOKYO: A Japanese spacecraft rocketed toward Mars on Tuesday on an unprecedented quest to explore its mysterious moons and bring back samples.

Five of the world’s space agencies joined forces for the five-year mission that will attempt to land a robotic prospector plus a rover on Phobos, the larger and closer of Mars’s two pint-sized moons.

The Japan Aerospace Exploration Agency, which is leading the bold sampling effort, launched the spacecraft before dawn from the country’s main spaceport on Tanegashima Island.

While NASA has successfully landed nine spacecraft on Mars over the past 50 years and China scored a 2021 touchdown, no one has ever ventured onto Phobos or its sidekick Deimos. And no one has managed to fetch samples from Mars, let alone its moons.

If successful, bits of dust, soil and rocks from Phobos will arrive on Earth in 2031.

“There’s a lot of adrenaline and a lot of excitement and a lot of wow,” said NASA astrophysicist Tom Statler, who’s involved with the project.

Phobos is a lumpy, potato-shaped rock just 22 kilometres or so across. Examining pieces of it can explain how Mars’s moons — and possibly moons elsewhere — came to be.

Dubbed MMX for Martian Moons Exploration, the $578 million mission features a hefty 5-tonne spacecraft that should reach Mars by late next summer. It will sync up with Phobos’ tight orbit around the red planet, before ejecting the French-German rover that’s named Idefix.

No bigger than a microwave oven, Idefix will plop onto Phobos by itself, bouncing for several minutes before coming to a halt in the moon’s extraordinarily low gravity.

The four-wheeled rover is designed to right itself if it lands upside down. All bets are off, though, if it sinks into soft soil or gets wedged between rocks, said the French Space Agency’s Julien Baroukh. Once the rover’s solar panels are deployed, the vehicle can no longer right itself, he added, which is why it will move at a glacial 1 millimetre per second.