The MMX mission (Martian Moons eXploration) is scheduled to launch from Tanegashima Space Center on Monday 19 October 2026 at 19:41 UTC (4:41:03 a.m. JST on 20 October) aboard H3 Flight No. 10. The spacecraft, led by the Japan Aerospace Exploration Agency (JAXA), will travel approximately one year to reach the Martian sphere in August 2027.
Over a five-year flight plan, MMX will orbit and inspect the Martian moons Phobos and Deimos, touch down on Phobos no earlier than December 2028 to gather at least 10 grams of material, and return the collected material to Earth inside a recovery capsule in 2031. International partners, including NASA, are providing flight instruments, sampling hardware, and navigation tracking.
MMX at a Glance
Japan’s Martian Moons eXploration (MMX) mission is scheduled to launch on H3 Flight No. 10 from Tanegashima Space Center at 19:41 UTC on Monday 19 October 2026, which is 4:41:03 a.m. Japan Standard Time (JST) on Tuesday 20 October. Led by the Japan Aerospace Exploration Agency (JAXA), MMX is designed as a world-first sample return mission to the Martian sphere. The mission will primarily explore Phobos, a Martian moon that has never been explored, and observe Deimos late in the mission.
The spacecraft will reach Mars in August 2027 after an interplanetary cruise lasting about one year. Once near Mars, MMX will enter a quasi-satellite orbit (QSO) relative to Phobos to map the surface, deploy a surface rover, and perform two soft landings. NASA states that surface sampling on Phobos will take place no earlier than December 2028. After departing the Martian sphere in 2030, the spacecraft will travel back to Earth, delivering its sample capsule for recovery in Australia in 2031.
| Mission Milestone | Scheduled Date or Window | Operational Activity |
|---|---|---|
| Launch | 19 October 2026 (19:41 UTC / 20 October 4:41:03 a.m. JST) | Liftoff on H3 Flight No. 10 from Tanegashima Space Center |
| Mars Arrival | August 2027 | Arrival at Mars after about a year of cruise |
| Phobos Orbital Phase | 2027 to 2030 | Operations in quasi-satellite orbit (QSO) around Phobos |
| Phobos Landings and Sampling | No earlier than December 2028 | Rover deployment followed by spacecraft landing to collect 10 g sample |
| Deimos Observations | Final phase | Observations of Deimos in the final phase |
| Mars Departure | 2030 | Single-maneuver engine ignition to escape the Mars sphere |
| Earth Return | 2031 | Separation of sample re-entry capsule; recovery in Australia |
JAXA’s site banner reads “The five year journey now begins.” Project manager Kawakatsu Yasuhiro notes that work on the project began almost ten years ago.
Why the Moons’ Origin Matters
Two hypotheses exist for the origin of the moons: the giant impact hypothesis and the capture hypothesis. Remote sensing and analysis of the returned sample will clarify which.
The giant impact hypothesis proposes that a massive collision occurred between a celestial body and Mars. The resulting impact scattered debris into orbit around the planet, where the fragments coalesced into Phobos and Deimos.
The capture hypothesis suggests that Phobos and Deimos are ancient asteroids originating from the outer Solar System that were captured by Mars’s gravity billions of years ago. Principal investigator Kuramoto Kiyoshi notes that the Martian moons closely resemble carbonaceous asteroids. These bodies are able to carry the ingredients for an atmosphere and water.
Tom Statler, MMX program executive and program scientist at NASA, explained the core question:
“Phobos and Deimos may be the remains of a massive impact on Mars that sent material into orbit around the planet, or they could be ancient asteroids that were captured by Mars’ gravity billions of years ago.”
Mars’s strong gravity makes landing and sample return from Mars itself hard. MMX uses Phobos instead. Phobos should have changed little over time.
Launch Details and Schedule for H3 Flight No. 10
The MMX spacecraft is scheduled to lift off from Tanegashima Space Center, Japan. JAXA designates the booster for this mission as H3 Flight No. 10. The date can move. The dates and times listed here reflect official project schedules published as of 16 October 2026.
| Time Zone | Launch Date | Scheduled Liftoff Time |
|---|---|---|
| Coordinated Universal Time (UTC) | Monday 19 October 2026 | 19:41 UTC |
| Japan Standard Time (JST) | Tuesday 20 October 2026 | 4:41:03 a.m. JST |
| Eastern Daylight Time (EDT) | Monday 19 October 2026 | 3:41 p.m. EDT |
The specific rocket configuration for H3 Flight No. 10 is not stated on the JAXA project pages read. An r/space forum headline referred to the vehicle as the most powerful version of the H3 rocket, but readers should confirm the formal vehicle configuration directly on JAXA’s official website. JAXA has not published public backup launch dates or the overall launch-window length on the pages referenced.
For general background on Japan’s launch programs and space capabilities, see our overview of the Japan Space Program.
The MMX Spacecraft Architecture and Instruments
The MMX spacecraft is structured into three modules: a propulsion module, an exploration module, and a return module. In its fully integrated configuration, the spacecraft measures 5.3 meters in height, 9.0 meters in length, and 4.5 meters in width. JAXA’s published pages do not state the total wet or dry spacecraft mass.
JAXA says MMX carries thirteen scientific mission instruments (MEGANE is listed as GRS and NS) and names these on its site:
- TENGOO
- OROCHI
- LIDAR
- MEGANE (comprising gamma-ray spectrometer GRS and neutron spectrometer NS subsystems)
- MIRS
- ROVER
- CMDM
- MSA
- C-SMP
- P-SMP
- SRC
- IREM
The mission strategy incorporates two distinct landings on the surface of Phobos. First, the rover lands and observes the surface. After the rover’s initial observations, the main spacecraft lands and collects the sample.
MMX builds on Hayabusa and Hayabusa2. In particular, JAXA calls out Hayabusa2’s successful second touchdown. Public outreach for the mission includes public relations ambassadors Suwa Makoto and Yoneda Ayu, both JAXA astronauts, who are MMX public relations ambassadors. A #GoodLuckMMX message campaign ran from 28 January 2026.
NASA’s Contributions to the MMX Mission
NASA’s contributions are MEGANE, the P-Sampler, communications and navigation support, and curation of about 15 percent of the sample. Detailed program descriptions appear on NASA’s planetary science division announcement.
NASA developed MEGANE (Mars-moon Exploration with Gamma rays and Neutrons), which translates to “eyeglasses” in Japanese. Developed by the Johns Hopkins Applied Physics Laboratory in collaboration with Lawrence Livermore National Laboratory, developed under NASA’s Discovery Program, managed by the Marshall Space Flight Center. The instrument measures neutrons and gamma rays from the surface to determine elemental composition. As detailed in NASA’s instrument delivery notice, NASA delivered the MEGANE instrument to JAXA for integration and system-level testing.
NASA’s contributions include the P-Sampler technology demonstration. Developed by Honeybee Robotics, a Blue Origin company, the P-Sampler is mounted directly onto one of the spacecraft’s landing legs. The P-Sampler collects a ground sample with bursts of high-pressure nitrogen gas. This mechanism complements JAXA’s C-Sampler, which extracts cores from a few inches deeper.
In addition to hardware, NASA provides communications and navigation support. NASA will receive and curate approximately 15 percent of the total returned sample material at the Johnson Space Center, sharing portions with researchers.
Nicky Fox, associate administrator for NASA’s Science Mission Directorate, emphasized the broader value of the mission:
“The samples from MMX will bring forth paradigm-shifting science on the Mars system for generations to come, especially as NASA prepares to send the first humans to Mars.”
For broader context on American deep-space initiatives, read our guide to the US Space Program.
What Happens After MMX Launches
The MMX mission spans approximately five years from launch to capsule recovery.
+-------------------------------------------------------------------+
| MMX MISSION FLOW |
| |
| Oct 2026 Aug 2027 Dec 2028+ 2030 |
| Tanegashima Mars Arrival Phobos Sampling Departure |
| Launch -----> Enter QSO ----> Deploy Rover ----> Single |
| (H3 No.10) around Phobos Land Spacecraft Maneuver |
| Collect >=10g | |
| V |
| 2031 |
| Earth Return |
| (Australia) |
+-------------------------------------------------------------------+
Following liftoff on H3 Flight No. 10, the spacecraft will spend approximately one year cruising toward Mars. The communication round-trip delay reaches up to 44 minutes.
The spacecraft arrives at Mars in August 2027. MMX enters a quasi-satellite orbit (QSO) similar to Phobos’ path.
During the QSO phase, MMX will observe the global shape of Phobos and dozens of candidate landing sites. The mission team may also tilt the QSO orbital plane to attempt observations of the moon’s polar regions. Once candidate sites are evaluated, operations proceed through two surface touchdowns:
- The ROVER lands first and observes the surface.
- The main MMX spacecraft descends to execute a touchdown on the surface. The main spacecraft then lands and collects the sample. NASA’s P-Sampler collects a ground sample with bursts of high-pressure nitrogen gas, and JAXA’s C-Sampler extracts cores from a few inches deeper.
JAXA’s goal is at least 10 grams of sample material, with instrument pages targeting an amount exceeding 10 grams. MMX observes Deimos in the final phase. JAXA also lists atmosphere and escape observations of Mars.
In 2030, the spacecraft will execute a single escape maneuver, firing its engines to exit the Mars sphere and begin the one-year return cruise. In 2031 MMX separates the re-entry capsule carrying the sample for atmospheric entry, to be recovered in Australia.
Strategic and Technical Significance of MMX
The MMX mission serves several major technological and scientific goals defined by JAXA:
- Completing round-trip interplanetary flight to and from the Martian sphere.
- Reaching the surface of the moons, sustained stay and advanced sampling.
- Communication optimized for deep-space operations.
How to Follow the MMX Mission Record
- Check the launch schedule at the JAXA MMX site.
- Review instrument technical details via NASA’s Planetary Science Division.