On October 20, 2026, the Japan Aerospace Exploration Agency (JAXA) successfully launched the Martian Moons eXploration (MMX) spacecraft aboard the H3 rocket No. 10 from the Tanegashima Space Center in Kagoshima Prefecture. Liftoff occurred at 4:41 a.m. Japan Standard Time. The probe separated from the rocket as planned, entered its intended orbit, and confirmed successful signal acquisition from ground stations, marking a major milestone for Japan’s space program.

MMX is the world’s first mission designed to collect and return samples of rocks and sand from one of Mars’ moons. Its primary target is Phobos, the larger of the two moons, which orbits roughly 6,000 km above the Martian surface and measures approximately 20–30 km in diameter. The spacecraft, weighing 4,480 kg, consists of three modules (one for the journey to Mars, one for Phobos exploration and sampling, and one for the return trip). It stands about 5.3 meters tall, spans roughly 9 meters with solar panels deployed, and features four landing legs. The H3 rocket used a two-engine, four-booster configuration, the most powerful version available.

The mission timeline calls for arrival in Mars orbit around August 2027. Once there, a jointly developed French-German rover (named Idefix) will land on Phobos to scout the surface. The main spacecraft will attempt two landings to collect at least 10 grams of material using complementary sampling techniques (one involving pressurized gas and another a coring method). It will also observe the smaller moon Deimos. After operations conclude, the probe is scheduled to depart Mars orbit in November 2030 and release a sample-return capsule for recovery on Earth in July 2031 (fiscal year 2031). The mission was originally planned for 2024 but was delayed after the H3 rocket’s maiden flight failed the previous year.

MMX is an international collaboration led by JAXA, with contributions from NASA (including the MEGANE gamma-ray and neutron instrument), the European Space Agency (communications), France’s CNES, and Germany’s DLR (rover and other elements). Total development cost is reported around ¥55.3 billion (approximately $578 million). Beyond collecting samples, the mission aims to investigate the origins of Mars’ moons—whether they are captured asteroids or debris from a giant impact—and to advance technologies relevant to future planetary exploration, including potential human missions to the Martian system. If successful, it will deliver the first samples returned from any moon other than Earth’s and provide the first physical material from the broader Martian system.

Context on Other International Mars Missions and Japan’s Asteroid Sample-Return Expertise

While MMX targets a Martian moon rather than the planet’s surface itself, it arrives amid a competitive global landscape for Mars exploration and sample return. NASA’s Perseverance rover, operating since 2021, has cached dozens of carefully selected rock and soil samples from Jezero Crater, including materials scientists hope could contain biosignatures. However, the joint NASA-ESA Mars Sample Return (MSR) architecture intended to retrieve those caches has been cancelled or indefinitely paused amid severe cost overruns (estimates ranging from $7–11 billion) and budget constraints. NASA is exploring simpler or commercial alternatives, but no firm replacement schedule exists for the 2030s. This leaves the Perseverance samples stranded on Mars for the foreseeable future.

China is advancing its own Tianwen-3 mission, targeting a 2028 launch window with dual Long March rockets: one for a lander/ascent vehicle (and possibly a helicopter) and another for an orbiter/return spacecraft. The goal is to collect and return Martian surface samples by around 2031—potentially the same year as MMX’s Phobos material arrives on Earth. China has already succeeded with Tianwen-1 (orbiter and rover) and is constructing a dedicated planetary-protection laboratory in Hefei to receive and study the samples, currently the only such facility under active development worldwide. Earlier Chinese lunar far-side sample return (Chang’e-6) has provided relevant technical experience.

Other nations have contributed orbital or flyby data. The UAE’s Hope orbiter continues atmospheric and climate observations, while India’s earlier Mangalyaan (Mars Orbiter Mission) demonstrated low-cost interplanetary capability. ESA previously partnered on the cancelled MSR Earth Return Orbiter and is contributing to MMX. Russia’s Roscosmos has longer-term Mars-Grunt concepts, but no near-term sample-return flights are funded. In short, by the early 2030s the first returned material from the Martian system may come from Japan’s Phobos samples and/or China’s surface samples, with NASA’s cached rocks remaining on the planet unless a new architecture is approved.

Japan’s leadership in MMX builds directly on its pioneering asteroid sample-return record. The original Hayabusa mission returned microscopic grains from the S-type asteroid Itokawa in 2010—the first asteroid samples ever brought to Earth—despite serious technical difficulties. Hayabusa2 followed with a more sophisticated campaign to the C-type asteroid Ryugu, arriving in 2018, deploying multiple small rovers and a lander, creating an artificial crater with an impactor, and collecting both surface and subsurface material. It returned approximately 5.4 grams to Australia in December 2020 (far exceeding the 0.1-gram goal). Analyses have revealed water-bearing minerals, organic compounds, and evidence of aqueous alteration in the early Solar System, closely matching rare CI chondrite meteorites and offering clues to the delivery of volatiles and organics to Earth. Hayabusa2 continues on an extended mission toward another small asteroid (1998 KY26) for a 2031 rendezvous. These successes established Japan’s expertise in precision navigation, touchdown sampling under microgravity, and sample curation—capabilities now being applied to the far more distant and complex MMX campaign at Phobos.

Together, these efforts position Japan as a leader in returning extraterrestrial material while the broader international community races to secure the first true Martian surface samples.