Japan's MMX spacecraft is scheduled to launch on Monday 19 October 2026 at 21.41.03 Swedish time, according to HurBra.se. The probe will depart from the Tanegashima Space Center in Japan aboard the country's H3 rocket, bound for the two moons of Mars. Its goal is to collect at least ten grams of material from Phobos and return it to Earth in 2031.
The Japan Aerospace Exploration Agency, JAXA, will stream the launch live. HurBra.se reports that coverage begins at about 20.46 Swedish time, roughly an hour before the planned liftoff.
Those times apply to the current launch schedule. As with any rocket launch, weather or technical faults could push the attempt back. JAXA has set a backup window running until 9 November in Japanese time, and a new departure time would be fixed separately if the launch slips.
Why it matters
Mars has two small moons, Phobos and Deimos. Unlike Earth's nearly spherical moon, both are irregular bodies that resemble oversized boulders. Phobos is the larger of the pair, with a longest dimension of about 27 kilometres, and it orbits very close to Mars.
After decades of observation, scientists still do not know for certain how these moons came to be. Bringing pieces of Phobos back for laboratory study could help settle that question, which is why the mission is being watched closely.
Two competing origin stories
One long-standing idea holds that Phobos and Deimos were asteroids captured by the gravity of Mars. Their dark surfaces and lumpy shapes fit that picture in several respects, according to HurBra.se.
The other is that the moons formed from debris thrown into orbit after a violent collision between Mars and another body early in the history of the solar system. Ejected material could then have gathered into the moons we see today.
Analysing Phobos material in laboratories on Earth would let researchers examine minerals, elements and isotopes far more precisely than instruments in orbit can manage. The chemical makeup of the samples could indicate where the material originated and under what conditions it formed. If Phobos is built from the remnants of an ancient impact with Mars, the samples may carry chemical signatures distinct from those of a captured asteroid.
A possible window onto Mars itself
Perhaps the most striking aspect of the expedition, as HurBra.se describes it, is that MMX could obtain material from Mars without ever landing on the planet.
Mars has been struck by meteorites for billions of years. Powerful impacts can throw rock and dust off the surface and out into space. JAXA assesses that Phobos may have accumulated considerably more Martian material than the outer moon Deimos, meaning the samples could contain fragments that originally came from the planet.
Such fragments might shed light on which minerals have existed on Mars, how water shaped its surface, and how its environment changed over the long history of the solar system. Researchers are also interested in organic compounds and chemical conditions relevant to the question of whether Mars once had environments in which life could have existed.
There is an important caveat. No one yet knows whether the material MMX actually gathers will include identifiable Martian material. The mission is therefore not a shortcut to guaranteed Martian rock, and it was not designed to prove directly that life ever existed on the planet. Even so, the samples could open a new window onto both Mars and the early history of its moons.
Landing in very weak gravity
Collecting a few grams of gravel may sound simple next to flying a probe hundreds of millions of kilometres across the solar system. The difficulty lies in the destination.
Gravity on Phobos is about one seventeen-hundredth of Earth's. A craft descending too quickly risks bouncing off the surface rather than settling on it.
MMX will first survey Phobos at close range and map candidate landing sites. Cameras and other scientific instruments will help the team pick areas that are both safe and scientifically valuable.
Before the main spacecraft collects its samples, a smaller robot named Idefix will examine the surface of Phobos. It was developed through cooperation between the French space agency CNES and Germany's DLR. The robot weighs about 25 kilograms on Earth, but on Phobos its weight would correspond to only about 15 grams under Earth conditions.
Idefix is to study the properties of the ground, among other tasks, and provide information that could assist the main craft during its later landings.
The sampling itself relies on two methods. One can take material from a depth of roughly two centimetres. The other uses pressurised nitrogen gas to lift loose surface material into a sample container. By combining the approaches, the team hopes to gather material with differing characteristics and build a fuller picture of the moon's uppermost layer.
What to watch
The immediate milestone is the launch window: liftoff is set for 19 October at 21.41.03 Swedish time, with JAXA's live broadcast starting about an hour earlier, and the backup period extends to 9 November if conditions intervene. After that, attention turns to the long cruise to Mars, the survey of Phobos, the Idefix deployment and the sampling attempts — and, if all goes to plan, to the return of at least ten grams of material in 2031.
