MMX Phobos launch puts sampler on course

Key Takeaways

The liftoff	JAXA launched the Martian Moons eXploration spacecraft on H3 flight No. 10 at 4:41:03 a.m. Japan Standard Time on Tuesday, Oct. 20, 2026, from the Tanegashima Space Center. The agency said separation came about 71 minutes and 13 seconds later.
Sample target	JAXA's schedule calls for a 10-gram sample from two soft landings on Phobos. Another page on the mission site says the goal is to return more than 10 grams, and Reuters reported an aim of at least 10 grams.
Return year	Reuters and the BBC say the craft should reach Mars in August 2027 and send samples back in 2031. JAXA schedules recovery of the capsule in Australia in 2031.
Moon origin	JAXA says the grains are meant to test two ideas: that Phobos and Deimos are debris from a giant impact on Mars, or that they are asteroids Mars captured.

The MMX Phobos launch lifted Japan's Martian Moons eXploration spacecraft off the Tanegashima Space Center on Tuesday, Oct. 20, 2026, aboard H3 rocket flight No. 10. The Japan Aerospace Exploration Agency said the craft separated about 71 minutes and 13 seconds later and entered its planned orbit.

The MMX Phobos launch from Tanegashima

JAXA's launch result says H3 flight No. 10 left the Tanegashima Space Center at 4:41:03 a.m. Japan Standard Time on Tuesday, Oct. 20, 2026. The agency said the rocket flew as planned. Separation was confirmed about 71 minutes and 13 seconds later, and JAXA said MMX had entered its predetermined orbit. That liftoff was 3:41 p.m. Eastern time on Monday, Oct. 19, 2026, or 19:41 GMT, Space.com reported.

Reuters reported that the flight was the H3's first interplanetary mission. The wire said the rocket's 2023 debut failed when the second-stage engine did not ignite.

Two landings for about 10 grams

JAXA's MMX site says the craft has three modules, for propulsion, exploration, and return. The schedule calls the target a 10-gram sample. The mission page says the craft must collect over 10 grams, and the main MMX page sets a goal of returning more than 10 grams. Reuters said the aim is at least 10 grams, and the BBC described the return as 10 grams.

Chrysa Avdellidou of Leicester University told the BBC, "You don't need to have kilos back from a surface in order to do science." The BBC said she is working with the Japanese team.

A rover is due on Phobos before the main craft lands. ESA's note of Tuesday, Oct. 13, 2026, names it Idefix, puts the mass at 25 kilograms, and says that would be the equivalent of 15 grams on Phobos. ESA said release is planned for early 2029. The Associated Press, in a Guardian story from Sunday, Oct. 18, 2026, said France and Germany built the rover for about 100 days of scouting around 2029.

The mission page says the rover lands first and the main craft then makes one landing to collect the sample. The homepage schedule says that sample comes from two soft landings. The AP described two sampling tries, the first using a NASA gas device and a Japanese corer to about 2 centimeters.

August 2027, then Australia in 2031

Reuters and the BBC say MMX should reach Mars in August 2027, with samples back in 2031. ESA's Oct. 13 note had already given August 2027, and said an orbit around Phobos would begin in September 2027. JAXA's schedule says the cruise takes about a year, followed by a quasi-satellite orbit around Phobos, then about a year home.

A quasi-satellite orbit keeps the spacecraft near Phobos while both circle Mars. JAXA says the mission will also watch Deimos from a distance and try flybys later. Space.com reported those flybys in the final months before a departure in November 2030.

JAXA schedules capsule recovery in Australia in 2031, and the BBC named the Woomera desert in South Australia. JAXA says a radio round trip can take up to 44 minutes. The AP said landing sites will be chosen from the rover's maps.

Impact debris or a captured asteroid

NASA's Phobos page, updated Nov. 3, 2024, lists the larger moon as 27 by 22 by 18 kilometers, orbiting Mars three times a day. Deimos is 15 by 12 by 11 kilometers and orbits about every 30 hours. Reuters put Phobos roughly 6,000 kilometers above the Martian surface.

JAXA's mission page gives two hypotheses. A giant impact may have left debris that became the moons, or Mars may have captured asteroids from the outer solar system. Sara Russell of the Natural History Museum, whom the BBC called deputy for MMX sample analysis, told the BBC that "the two hypotheses will produce very distinct results." She also said the sample "may actually contain grains of Mars as well."

The AP, citing JAXA officials before launch, said Martian material is expected to make up about 0.1 percent of the collection. Yasuhiro Kawakatsu, the project manager, told the AP the moons are "the most important unclimbed mountains in the solar system." Kiyoshi Kuramoto, the principal investigator, told the AP, "We can almost certainly come to a conclusion by analysing soil samples."

Mars rock still waiting on the surface

JAXA says nothing from the Martian system has been brought to Earth before. The agency cites Hayabusa and Hayabusa2, which returned asteroid samples.

NASA's Mars Sample Return page, updated Thursday, Sept. 17, 2026, describes that project in the past tense, as a proposed NASA and ESA campaign to return rock stored by the Perseverance rover. The BBC reported that Congress halted funding and that the follow-on flight was effectively cancelled. The BBC said Perseverance has been collecting samples since 2021.

Hou Zengqian, chief scientist of China's Tianwen-3, told Xinhua in a report dated Sept. 4, 2026, that the mission is planned to launch around 2028 and to return Martian samples in the same flight. JAXA says MMX carries 13 scientific instruments, including NASA's MEGANE gamma-ray and neutron instrument, built by the Johns Hopkins Applied Physics Laboratory with Lawrence Livermore National Laboratory. ESA said the partners are NASA, France's CNES, Germany's DLR, and ESA, with JAXA in the lead.