Japan Launches MMX to Bring Back the First Samples From Mars’ Moon Phobos

Japan’s Martian Moons eXploration mission, known as MMX, lifted off at 4:41 a.m. Japan time on Oct. 20, 2026 (3:41 p.m. Eastern on Oct. 19) from the Tanegashima Space Center aboard an H3 rocket. The MMX launch starts a roughly five-year round trip that aims to bring the first samples from Mars’ moon Phobos back to Earth in 2031.

Image: Phobos passing over Mars, processed from ESA Mars Express data, used for illustration. Photo: Andrea Luck, via Wikimedia Commons (CC BY 2.0).

How the MMX launch unfolded

The Japan Aerospace Exploration Agency (JAXA) said the H3 rocket, flying as flight No. 10, performed as planned. About 71 minutes and 13 seconds after liftoff, controllers confirmed that the MMX spacecraft had separated from the rocket and entered its planned orbit toward Mars.

It was the first interplanetary mission for the H3, Japan’s newest launcher. According to the MMX press kit, the spacecraft flew on the H3-24L configuration, the most powerful version, which uses two first-stage LE-9 engines and four solid rocket boosters. The rocket stands about 63 meters tall and weighs about 574 tons before payload is added. The spacecraft itself has a mass of about 4,480 kilograms.

The European Space Agency, a partner on the mission, called the launch a success within hours. “The launch was spectacular, and JAXA’s H3 launcher performed fantastically to send MMX onward to Mars,” ESA project scientist Elliot Sefton-Nash said in an ESA statement.

The Phobos sample return plan, step by step

ESA’s mission summary lays out a long and carefully staged timeline:

• August 2027: MMX is expected to enter orbit around Mars after roughly a year in transit.
• September 2027: The spacecraft begins orbiting Phobos in what planners call a “quasi-satellite orbit,” making it the first spacecraft to circle that moon.
• Early 2029: MMX releases IDEFIX, a small rover built by the French space agency CNES and the German Aerospace Center (DLR). Mission materials list the rover at about 25 kilograms. It is meant to be the first rover on Phobos and to measure surface conditions before the main spacecraft touches down.
• 2030: The main spacecraft lands on Phobos to collect material. JAXA’s press kit says two landings are planned.
• 2031: A return capsule carrying at least 10 grams of Phobos material lands in Australia, after a flyby study of Mars’ smaller moon, Deimos, on the way out.

If it works, MMX would be the first mission to collect samples from the surface of any moon other than our own, and the first spacecraft to come home after visiting the Mars system.

Why scientists care about Mars’ moons

Phobos and Deimos are small, dark and oddly shaped, and scientists have argued for decades about where they came from. One idea is that they are asteroids captured by Mars’ gravity. Another is that they formed from debris thrown into orbit when something large slammed into Mars.

NASA is supplying an instrument called MEGANE, a gamma-ray and neutron spectrometer that will measure the chemical makeup of Phobos’ surface from orbit. NASA says those measurements should help settle whether the moons are captured asteroids or the products of a giant impact. JAXA also frames the mission around a bigger question: how water and organic matter were carried to rocky worlds in the early solar system.

The returned samples will be small, but ESA notes that modern lab measurements can pull a great deal of information out of tiny amounts of material. Once the capsule is recovered in Australia, the samples will go to Japan to be extracted and catalogued, and partner agencies plan to open them to outside researchers.

A global team, and a test for future Mars trips

MMX is led by JAXA, working with NASA, CNES, DLR and ESA. ESA provided the deep-space communication equipment on the spacecraft and ground-station support through its Estrack network. JAXA has also pitched the Martian moons as possible staging points for future human missions to Mars.

The ability to fly to Mars and back is a big deal on its own. ESA points out that the same round-trip skills could feed into future robotic missions that return samples from the Martian surface, and eventually crewed flights.

Space science keeps producing headlines this fall. The Boston Report recently covered astronomers’ discovery of the first green star, a rare white dwarf, and SpaceX’s progress in our explainer on Starship Flight 14 and its first orbit. For more on how physics research is being recognized, see our story on the 2026 Nobel Prize in Physics for IceCube’s Francis Halzen.

What to watch next

The next big milestone is Mars orbit insertion in August 2027, which JAXA calls the greatest challenge of the first half of the mission. A missed or weak engine burn there could end the mission early. After that, the team turns to months of detailed mapping of Phobos before choosing safe landing sites for IDEFIX and the main spacecraft.

Sources

• JAXA: Launch result of the Martian Moons eXploration (MMX) spacecraft aboard H3 Launch Vehicle flight No. 10
• ESA: MMX lifts off to Mars’s moon Phobos
• ESA: Mars moon lander set to launch on 19 October
• JAXA: MMX mission press kit (PDF)
• NASA Science: NASA to help unlock mysteries of Mars’ moons
• DLR: MMX facts and figures
• Wikimedia Commons: Phobos over Mars, ESA Mars Express (CC BY 2.0)