Japan's MMX mission set to launch Monday to bring back the first sample from Mars' moon Phobos

As of 1:50 p.m. ET, Sunday, Oct. 18, 2026

The Japan Aerospace Exploration Agency plans to launch its Martian Moons eXploration (MMX) spacecraft on Monday, Oct. 19, on a mission to collect the first sample from Mars' moon Phobos and return it to Earth.

JAXA said the H3 rocket, flight No. 10, is scheduled to lift off from the Yoshinobu Launch Complex at Tanegashima Space Center at 4:41:03 a.m. Tuesday, Oct. 20, Japan time, which is 3:41 p.m. ET Monday. The agency has reserved Oct. 21 through Nov. 9 as backup launch dates, and said the launch time may change.

The mission

MMX is led by JAXA with NASA, the French space agency CNES, the German Aerospace Center DLR and the European Space Agency. It carries 11 science instruments: seven on the main spacecraft and four on a 25-kilogram rover called Idefix, according to ESA.

The spacecraft is expected to enter orbit around Mars in August 2027 and begin orbiting Phobos in September 2027, ESA said. After studying Phobos and Mars' other moon, Deimos, from a distance, it is scheduled to release Idefix onto Phobos in early 2029.

In 2030, the main spacecraft is planned to land on Phobos and collect samples. A return module is due back at Earth in 2031, dropping at least 10 grams of Phobos material in a capsule that will land in Australia before being taken to Japan.

Why Phobos

Scientists do not know how Mars' two moons formed. They may be captured asteroids, or debris thrown into orbit by a giant impact on Mars, ESA said; samples could help answer the question. "The data and samples returned by MMX are a window to study the evolution of Mars and the Solar System," said Elliot Sefton-Nash, ESA's MMX project scientist.

ESA said MMX would be the first spacecraft to orbit Phobos and the first to collect samples from the surface of a moon other than Earth's.

JAXA plans to stream the launch on its YouTube channel.

Why it matters

If it succeeds, MMX would be the first mission to visit the Mars system and come back to Earth, a step that space agencies see as groundwork for future sample returns from Mars itself.