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NewsJapan (JAXA)

Japan’s MMX is set to launch Oct 20 for a piece of Mars’s moon Phobos

JAXA plans to launch its Martian Moons eXploration mission at 04:41 Japan time on Oct 20 (19:41 UTC on Oct 19) on an H3 rocket. The samples are due back in Japan’s fiscal 2031.

By Mars Progress · Edited by Aleksandar Simov

Published 2 min read

Phobos, a lumpy, cratered moon, against black space
Phobos, the larger of Mars’s two moons, where MMX is due to land and collect its sample. NASA’s Mars Reconnaissance Orbiter took this picture on Mar 23, 2008.Image: NASA/JPL-Caltech/University of Arizona

Japan’s space agency, JAXA, plans to launch its Martian Moons eXploration mission, MMX, at 04:41 Japan time on Oct 20, 2026, which is 19:41 UTC on Oct 19. It will fly on the tenth H3 rocket from the Tanegashima Space Center. If the launch slips, JAXA has reserved Oct 21 to Nov 7.[1]

MMX is a Sample returnA sample return mission collects rock, soil or dust from another world and brings it back to Earth to study in labs.More in the glossary mission. It’s due to reach Mars in 2027, spend about three years studying its two small moons, land on the larger one, Phobos, and bring more than 10 grams of it back to Earth in Japan’s fiscal 2031, which ends in March 2032.[2][3] JAXA says it would be the first mission to return material from the Mars system.[3]

The 4,480 kg spacecraft also carries IDEFIX, a 25 kg rover built by France’s CNES and Germany’s DLR, which is due to land on Phobos in 2029, and MEGANE, a NASA instrument that will measure what Phobos is made of.[2][4]

“Seeing MMX lift off will be an emotional milestone for all of us,” said Yasuhiro Kawakatsu, the MMX project manager, in DLR’s Sep 1 announcement that the spacecraft and rover were ready for launch.[4] On Sep 24, JAXA showed reporters the control room that will fly the mission, Nikkei reported.[7]

Why Phobos?

Nobody knows how Mars got its moons. They may be asteroids that Mars captured, or rubble thrown into orbit when something large hit Mars. JAXA says the sample “will settle the debate.” Because Phobos has been hit by debris blasted off Mars, its surface may also hold small pieces of Mars itself.[2][4]

The rocket

This will be the H3’s third flight since a failure on Dec 22, 2025 that lost a navigation satellite. A test flight of a new H3 version flew as planned on Jun 12, 2026, as did the ninth H3 on Aug 11, and JAXA announced the MMX launch date nine days later.[1][5][8][6]

Mars progress1 of 6 steps done, 2 under way. Only dates that agencies and companies have announced count.How close are we? →

Related

MissionMMX missionReferencePhobos, explainedReferenceHow many moons does Mars have?

Sources

  1. JAXA — Launch of the MMX spacecraft onboard the H3 Launch Vehicle No. 10Primary · checked Oct 2, 2026
  2. JAXA — MMX press kit (revised Sep 16, 2026)Primary · checked Oct 2, 2026
  3. JAXA — MMX: Martian Moons eXplorationPrimary · checked Oct 2, 2026
  4. DLR — Off to the moons of Mars: MMX mission and Idefix rover ready for launchPrimary · checked Oct 2, 2026
  5. JAXA — Results of the H3 Launch Vehicle Flight No. 8Primary · checked Oct 2, 2026
  6. JAXA — Launch result of the H3 Launch Vehicle No. 9Primary · checked Oct 2, 2026
  7. Nikkei — MMX mission control room shown to the press (Japanese)Secondary · checked Oct 2, 2026
  8. JAXA — Launch Result of H3 Launch Vehicle flight No.6, 30 configuration Test VehiclePrimary · checked Oct 4, 2026