JAXA MMX launches on H3 to bring back Phobos samples

Japan's space agency JAXA launched its MMX probe toward Mars at 4:41 a.m. on October 20, 2026, Japan time. If the mission works, it will be the first to bring home samples from a Martian moon. The launch also gives Japan's new H3 rocket a high-profile success on its 10th flight.

The launch

The H3 rocket lifted off from the Tanegashima Space Center in southern Japan. That was 19:41 UTC on October 19. About 71 minutes and 13 seconds later, the spacecraft separated from the rocket and entered its planned path, JAXA's launch report says. "The H3 Launch Vehicle flew as planned," the agency wrote.

JAXA then received signals from the probe as expected, confirming it was working normally, AFP reports. "I'd dreamt of this day, so I'm incredibly happy," JAXA scientist Mari Aida told AFP.

The H3 is Japan's new main rocket, built by JAXA and Mitsubishi Heavy Industries. It is about 207 feet tall, with two LE-9 main engines and four solid rocket boosters, according to Interesting Engineering.

What MMX will do

MMX stands for Martian Moons eXploration. Its target is Phobos, the larger of Mars's two small moons, which is about 14 miles across. JAXA leads the mission, with NASA, the French and German space agencies CNES and DLR, and ESA as partners.

The probe will reach Mars around August 2027 and spend about three years in the Mars system. It will drop Idefix, a French-German rover, onto Phobos to study the surface and help make the main landing safe. AFP says Idefix will be the first vehicle to travel across Phobos.

The main spacecraft will then touch down twice to collect at least 10 grams of material. The sources differ on when. Interesting Engineering says late 2028 or 2029, while an ESA mission graphic places the sampling in 2030.

Milestone	Date
Launch	October 20, 2026 (JST)
Arrival in Mars orbit	August 2027
Orbit around Phobos	September 2027 (ESA)
Phobos landings	Late 2028 or 2029 (Interesting Engineering); 2030 (ESA graphic)
Departure for Earth	November 2030
Sample capsule lands in Woomera, Australia	2031

On the way home, the return module will also study Deimos, Mars's smaller moon, and Mars itself, according to ESA.

Why Phobos matters

No spacecraft has landed on either Martian moon and returned samples, Interesting Engineering notes. AFP adds that MMX aims to be the first round trip to the Martian region. The probe will collect material from two different sites, according to ESA, so scientists get more than one kind of surface.

NASA expects a lot from the material. "The samples from MMX will bring forth paradigm-shifting science on the Mars system for generations to come," said Nicky Fox, head of NASA's Science Mission Directorate, on JAXA's live stream.

The mission is also a long commercial job. Mitsubishi Electric says it will support operations all the way back to Earth. Interesting Engineering puts the budget at $578 million.

What this means for developers

MMX is science first, but it also matters for anyone who builds satellites or depends on launch capacity.

• Count the H3 as a working option. JAXA says the rocket flew as planned on a flagship mission. Teams choosing a launcher for satellites can weigh that record against the alternatives.
• Watch the rover. Idefix has to move across a moon only about 14 miles wide, far from any human help. How it performs will matter to anyone building robots that must work on their own.
• Expect years of observations first. MMX will study Mars from orbit and scout landing sites long before the samples come home. Watch the partner agencies for results from that phase.
• Note the timeline risk. The sources already disagree on when sampling happens. Missions this long slip, so plan around the 2031 return as a target, not a promise.