Japan's JAXA schedules launch of Martian Moons eXploration mission for 20 October

JAXA has set the launch of its Martian Moons eXploration (MMX) spacecraft for 04:41 Japan time on 20 October. The mission aims to land on Mars's moon Phobos, collect a sample and return it to Earth in 2031.

Published 18 Oct 2026, 21:00 CEST (Europe/Oslo) · 18 Oct 2026, 19:00 UTC

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Launch schedule

The Japan Aerospace Exploration Agency (JAXA) said on 18 October that it will launch its Martian Moons eXploration (MMX) spacecraft on Tuesday 20 October at 04:41:03 Japan time. That is 19:41:03 UTC on Monday 19 October, or 21:41 in Norway. The launch will be on an H3 rocket from the Yoshinobu Launch Complex at the Tanegashima Space Center in southwestern Japan.

JAXA has reserved a launch period from 21 October to 9 November, and said the launch time may differ on those days. ESA says the launch will be streamed live on JAXA's YouTube channel.

What the mission is for

MMX is a JAXA-led mission to Phobos, one of Mars's two moons. According to ESA and NHK, it is designed to be the first mission to collect a sample from a moon of Mars and bring it back to Earth. ESA says it would also be the first spacecraft to orbit Phobos and the first to collect samples from the surface of a moon other than Earth's own.

The spacecraft is planned to reach Mars in August 2027. It will study Phobos and Deimos, the other moon, from a distance and deploy a 25-kg rover called Idefix before landing on Phobos to collect at least 10 grams of material. The sample is due back on Earth in 2031, where it will land in Australia before being transferred to Japan, according to ESA.

International contributions

NASA, the French space agency CNES, the German Aerospace Center DLR and ESA are taking part. NASA is providing a gamma-ray and neutron spectrometer called MEGANE, a sampling technology demonstration called P-Sampler, and communications and navigation support from its Deep Space Network. NASA says it will curate about 15% of the returned sample at its Johnson Space Center in Houston.

The open question

Scientists have not settled how Phobos and Deimos formed. One explanation is that they are debris from a giant impact on Mars. The other is that they are asteroids captured by Mars's gravity. The agencies say samples from Phobos are intended to help answer this.

How this was checked

Confirmed by at least two independent sources

JAXA announced on 18 October that the launch is set for 20 October at 04:41:03 Japan time, with a reserved launch period from 21 October to 9 November, from the Tanegashima Space Center (JAXA). The launch time may vary during the reserved period (JAXA).

04:41:03 Japan time on 20 October is 19:41:03 UTC on 19 October (NHK, NASA and ESA give equivalent times).

The rocket is an H3, flight number 10 (JAXA). The mission is led by JAXA with NASA, CNES, DLR and ESA taking part (ESA, JAXA).

The mission aims to land on Phobos, collect surface material and return it to Earth. At least 10 grams is planned (ESA, NHK). Return to Earth in 2031 (JAXA, ESA). NHK gives the fiscal year ending March 2032, which matches JAXA's fiscal year 2031.

The spacecraft is expected to reach Mars in August 2027 (NASA, ESA). It carries a rover called Idefix (JAXA, ESA). ESA gives its mass as 25 kg.

NASA is providing the MEGANE instrument, the P-Sampler sampling technology demonstration, and Deep Space Network support. NASA will curate about 15% of the returned sample (NASA).

Scientists have two main explanations for how Mars's moons formed. One is a giant impact on Mars. The other is capture of asteroids by Mars's gravity (JAXA, ESA, NASA).

Not confirmed — treat with caution

The launch had not taken place when this article was published. We do not report any outcome, and the date and time may change within the reserved launch period. We will update this article after the launch.

Outlets and agencies give slightly different wording for the later mission schedule, including the timing of the Phobos landing and sample collection. We have not stated a landing date.

NHK reported a development cost of 55.3 billion yen. We found no second source, so we have not included it.

We attempted to read an AP News explainer on the mission but could not load it, so we have not used it.