We've spent decades dropping rovers onto the rust-red dirt of Mars, but we've never managed to bring home a pristine piece of its neighborhood. That changes now. Japan's Aerospace Exploration Agency, known as JAXA, is launching the Martian Moons Exploration mission, or MMX, aboard an H3 rocket from the Tanegashima Space Center. It's a massive undertaking. The goal is simple to state and brutally difficult to execute: travel to the Martian system, land on the mysterious moon Phobos, scoop up regolith, and haul it all the way back to Earth by 2031.
If successful, this marks the first time humanity brings physical material back from a Martian moon. It's a massive leap past standard orbital photography.
Why Phobos and Deimos Keep Scientists Up at Night
The origin story of Mars' two tiny moons, Phobos and Deimos, remains one of planetary science's favorite arguments. Are they captured asteroids pulled in by Martian gravity, or are they chunks of Mars itself blasted into orbit by an ancient, cataclysmic impact?
They look like lumpy potatoes. They don't look like typical moons.
Captured asteroids would mean they carry ancient material from the outer solar system, untouched for billions of years. Impact debris would mean they are basically pieces of ancient Mars preserved in deep space. Because Mars has erased much of its oldest surface through heavy erosion, volcanism, and shifting tectonics, those moons might hold the pristine geological memory of the planet's violent youth.
JAXA isn't just guessing. The MMX spacecraft will spend years in a quasi-satellite orbit around Phobos, mapping its topology, studying its gravity, and searching for organic residues.
The Engineering Nightmare of Landing on a Potato Moon
Landing on a celestial body with almost no gravity is uniquely terrifying. Traditional parachutes won't work because there is no atmosphere to speak of. Thrusters kick up dust that can blind navigation systems.
The MMX spacecraft breaks down into three distinct modules: a propulsion module, an exploration module, and a return module. Total mass sits around 2,100 kilograms. Once the probe reaches the Martian sphere after a year-long cruise, it enters a delicate dance around Phobos.
The plan requires two separate soft-landing operations on the surface of Phobos. The craft will use a pneumatic sampling system to vacuum up at least 10 grams of regolith. Ten grams sounds small, but ask any scientist working with asteroid samples from missions like Hayabusa2 how much high-value chemistry you can extract from a handful of space dust. It's more than enough to change textbooks.
After grabbing the samples, the craft will also execute flybys of Deimos to compare compositions before firing its main engines to break free from Mars' gravitational pull in 2030.
Global Collaboration in Deep Space
Japan isn't flying this mission alone. NASA, the European Space Agency, and France's CNES are all tied into the project. NASA is providing scientific instruments like a neutron and gamma-ray spectrometer to help analyze the composition of Phobos. ESA is supplying critical deep-space communication hardware to keep signals stable across millions of miles of void.
When the return module finally nears Earth in 2031, it will drop a specialized re-entry capsule. That capsule will streak through the atmosphere and parachute down in Australia, mirroring the successful returns of previous Japanese sample missions.
Space exploration is moving past simple flybys. We are entering an era of physical retrieval. The answers sitting on a tiny rock orbiting Mars might finally explain how rocky planets build themselves and whether the raw ingredients for life are common across the galaxy.
