JAXA Plans MMX Launch to Return First Samples from Mars Moon Phobos

Key facts

• The Japan Aerospace Exploration Agency (JAXA) is launching the Martian Moons eXploration (MMX) mission on October 19, 2026 (3:41 p.m. EDT / 4:41 a.m. Oct. 20 local time) aboard an H3 rocket from Tanegashima Space Center in southern Japan.
• MMX will be the first spacecraft to land on Mars' moon Phobos and return a sample of its regolith to Earth, targeting at least 10 grams (0.35 ounces) collected during two landings in 2030.
• The spacecraft, about 30 feet (9 meters) long and weighing about 5 tons, comprises three modules — propulsion, exploration, and return — with only the return module coming home with samples in a heat-protected capsule landing in Australia in 2031.
• MMX should arrive at Mars in August 2027, enter a quasi-satellite orbit around Phobos, spend about three years studying the moon, drop the IDEFIX rover in early 2029, and fly by Deimos on its return journey.
• The 55-pound (25 kg) IDEFIX rover, built by France's National Centre for Space Studies (CNES) and the German Aerospace Center (DLR), will conduct a roughly 100-day surface mission around 2029 to scout terrain for the later sampling.
• JAXA leads the mission with NASA contributing science instruments including the MEGANE gamma-ray and neutron spectrometer and a pneumatic sampling device that blasts surface grains into a container with pressurized nitrogen; France supplied an infrared spectrometer, and the European Space Agency (ESA) provides scientific and operational support including a deep space communication device.
• MMX carries 13 instruments, including two ultra-high-definition cameras built with Japan's broadcaster NHK to film Mars and its moons in 8K, plus a telescopic camera resolving features about 16 inches (40 cm) across, a wide-angle multicolor imager, and a laser altimeter.
• The mission's two main science goals are determining how Phobos and Deimos formed — whether captured asteroids or debris from a large impact on Mars — and investigating the origins of Mars' ancient atmosphere and water; samples may also shed light on the origins of life in the solar system.
• Phobos measures about 27 by 22 by 18 kilometers and orbits Mars at about 6,000 kilometers distance three times a day; scientists chose it over Deimos because it is closer to Mars, and material from Mars is expected to make up about 0.1% of the collected sample.
• Previous attempts to reach Phobos failed: the Soviet Union lost both its Phobos probes in 1988 and 1989, and Russia's Phobos-Grunt sample return mission never escaped Earth orbit in 2011.
• Japan's earlier Hayabusa missions returned asteroid samples in 2010 and 2020, and Phobos sample data could help scientists consider using a Martian moon as a base for future manned missions to Mars.
• Landing on Phobos, which has just one two-thousandth of Earth's gravity, is a challenge; MMX's exploration module has four-legged landing gear with shock absorption, and the rover has wheels that can gain traction in low gravity and right itself if it tips over.