Japan Launches MMX to Bring Back the First Sample From a Moon of Mars

Nobody knows for certain where Mars' two small moons, Phobos and Deimos, came from. Japan has just sent up a spacecraft to find out, by doing something no mission has done before: bringing a piece of a Martian moon back to Earth.

The Japan Aerospace Exploration Agency's Martian Moons eXploration mission, known as MMX, lifted off from Tanegashima Space Center on Monday, October 19, at 19:41 UTC, early on October 20 in Japan. If all goes to plan, it will reach Mars in 2027 and return at least 10 grams of Phobos to the Australian outback in 2031, likely making it the first sample ever brought back from the Mars system.

How MMX Got Off the Ground

MMX rode an H3 rocket in its most powerful configuration, with two main engines and four solid rocket boosters. The 4,480 kilogram spacecraft separated from the rocket's upper stage in orbit and began its roughly 10 month cruise to Mars. It was the only Mars launch of this planetary window, which opens about every 26 months, and the third H3 flight of the year for Japan.

The spacecraft is built in three modules. A propulsion module handles the trip to Mars, an exploration module carries the landing legs, sampling tools, rover and most of the 13 science instruments, and a return module will bring the samples home, releasing a capsule that lands in the Woomera Prohibited Area in South Australia.

The Plan for Phobos

After arriving at Mars in August 2027, MMX is expected to move about a month later into a so-called quasi-satellite orbit around Phobos. Phobos is only about 22 kilometers across, and its gravity is too weak for a normal orbit, so the spacecraft will instead circle Mars in step with it.

MMX will then spend more than a year mapping Phobos with high-resolution cameras, a laser altimeter, spectrometers and a dust monitor that will search for a faint ring of material around Mars. Before landing, it will drop a small four-wheeled rover called IDEFIX, built by the French and German space agencies, from tens of meters up. Phobos' gravity is so weak that the rover should survive the fall, right itself and start measuring the surface.

The main spacecraft will then land to collect samples, possibly twice, using two methods for redundancy: a coring device on a robotic arm and a pneumatic sampler that blows pressurized gas to kick surface material into a collection chamber. MMX will also make flybys of Deimos before heading home in 2030.

Why the Moons of Mars Matter

Scientists have argued for decades about how Phobos and Deimos formed. One idea is that they are asteroids captured by Mars' gravity. Another is that a giant impact blasted material off Mars that later came together as moons. A third combines the two: a captured object shredded into a ring of debris that slowly reassembled. Phobos is also slowly spiraling inward toward Mars and is expected to break apart or crash into the planet in tens of millions of years, which makes it one of the strangest moons in the solar system.

A sample in a lab on Earth could finally settle the question. Material that matches Mars would point to an impact; material that looks like a primitive asteroid would point to capture. Either answer would also tell scientists about the early solar system, including how water and other ingredients for life may have been delivered to the inner planets.

Japan has pulled off this kind of mission before. Its Hayabusa probe returned grains from the asteroid Itokawa in 2010, and Hayabusa2 brought back about 5 grams from the asteroid Ryugu in 2020. NASA's OSIRIS-REx followed with samples from the asteroid Bennu in 2023.

What It Means for Silicon Valley

MMX is an international mission with American hardware on board. NASA contributed an instrument called MEGANE, built at the Johns Hopkins Applied Physics Laboratory, that will measure gamma rays and neutrons to work out what Phobos is made of. NASA also provided the pneumatic sampler, developed by Honeybee Robotics, now part of Blue Origin, and the agency's Deep Space Network will help track the spacecraft.

The sampler also has a startup-style origin story. The technology, called PlanetVac, began as a low-cost idea backed in part by The Planetary Society, the Pasadena nonprofit, which helped fund a 2018 rocket test and an early prototype. A version later flew on Firefly Aerospace's Blue Ghost lander, which touched down on the Moon in 2025 and collected samples. Small, cheap demonstrations that lead to flagship missions are a pattern Silicon Valley investors know well.

The bigger story is about who can still bring samples home. NASA's own plan to return rock samples from Mars has been mired in cost and schedule problems, while Japan and China are moving ahead. China's Tianwen-3 mission aims to return samples from Mars itself around 2031. For American engineers, the commercial space companies of California included, MMX is a reminder that deep space exploration is becoming a crowded, international race.

Will MMX Solve the Mystery of Mars' Moons?

The prospects are strong, and the team has a track record. JAXA has the most experience of any agency in collecting samples from small bodies and bringing them home, and MMX carries two independent sampling systems in case one fails. If it succeeds, scientists will have the first physical sample from the Mars system, collected from a moon that may contain material blasted off Mars itself. That could make Phobos a kind of library of Martian history, without the cost and difficulty of landing on and launching from the planet.

There are real risks, too. Landing on a small, low-gravity moon is tricky, because the spacecraft can bounce or tip, and the surface may be loose dust, solid rock or something in between. The quasi-satellite orbit has never been flown around Phobos before, and radio signals can take up to about 20 minutes each way between Earth and Mars, so much of the close work near the surface has to run on its own software. The mission must also survive more than four years of deep space travel and operations, and a long trip home, before scientists get anything to study.

Then there is scientific uncertainty. Even with samples in hand, the answer may not be simple. Phobos has been bombarded for billions of years, and its surface could be a mix of its own material and debris from Mars and elsewhere. Researchers may end up arguing over what the samples mean, just as they do about meteorites.

The mission also lands in a period of tight budgets and shifting priorities. International partners share the cost and the risk, but they also depend on each other's funding decisions over many years, from instrument support to tracking stations. A delay or cut on one side can ripple across the whole mission, and the sample analysis that follows the return will need years of funding of its own.

The signals to watch are specific. Will MMX arrive at Mars on schedule in August 2027 and reach its orbit around Phobos? Will the IDEFIX rover survive its drop and send back data? Will both sampling tools work? And will the capsule land safely in Australia in 2031, ahead of China's planned Mars sample return?

From Orbit to Outback

At Sparknify we follow the machines that bring things home from space. Earlier today we looked at SpaceX Launches Starfall Lab and a Cancer Drug Test on Bandwagon-5, where returning capsules are turning low Earth orbit into a place to run experiments. MMX is the deep space version of the same idea, with a round trip measured in years instead of weeks. Both depend on the same hard skill: getting a capsule through the atmosphere and onto the ground intact.

Ten grams of moon dust could finally answer a question that is older than spaceflight itself.

Subscribe to Sparknify for Silicon Valley tech news and the people behind it.