Japan is preparing to send a spacecraft toward Mars on a mission designed to bring material from the Martian moon Phobos back to Earth. The Japan Aerospace Exploration Agency’s Martian Moons eXploration mission, known as MMX, is scheduled to launch on an H3 rocket from Tanegashima on October 20 at 4:41 am Japan Standard Time.
If the mission follows its current schedule, MMX will arrive at Mars in August 2027, collect samples no earlier than December 2028, and return them to Earth in 2031. The campaign is a major attempt to answer a long-running question in planetary science: where did Mars’s two small moons come from?
A sample-return mission focused on Phobos
MMX will study both Phobos and Deimos, but its primary target is Phobos, the larger moon. Phobos is about 22 kilometers across, while Deimos is about 12 kilometers across. The two bodies have long invited competing explanations. One hypothesis holds that they are asteroids captured by Mars’s gravity. Another proposes that they are debris left after a collision involving Mars and another object.
Observations from afar have not resolved that dispute. Material returned to laboratories on Earth could provide a more direct way to test which origin story best fits the moons’ composition and history. The mission’s goal is therefore larger than collecting an unusual extraterrestrial specimen: it is an effort to investigate conditions and events in the early solar system.
At a NASA briefing, Planetary Science Division Acting Director Lindsay Hays said MMX is intended to collect Phobos material for return to Earth. The source article reports that the spacecraft’s sample container is planned to land in Australia.
NASA instruments join an international project
NASA is contributing two scientific instruments to MMX. One is MEGANE, short for Mars-moon Exploration with GAmma rays and NEutrons, a spectroscopy instrument developed by the Johns Hopkins University Applied Physics Laboratory. The other is P-Sampler, a pneumatic collection mechanism from Honeybee Robotics, a Blue Origin company.
The contributions underline the international character of the mission. In addition to JAXA and NASA, the project includes France’s CNES, Germany’s DLR, the European Space Agency and the Australian government. Such cooperation spreads both technical work and scientific participation across agencies that have experience in planetary exploration.
- Launch vehicle and site: JAXA’s H3 rocket from Tanegashima, Japan.
- Planned Mars arrival: August 2027.
- Earliest planned sample collection: December 2028.
- Planned Earth return: 2031.
- Primary scientific target: Phobos.
MEGANE’s gamma-ray and neutron spectroscopy is part of the effort to characterize the Martian moons, while P-Sampler is designed for collection. Together, the instruments are tied directly to the mission’s central scientific task: understanding the material that makes up Phobos and how it relates to competing theories of origin.
JAXA builds on a sample-return record
MMX will be JAXA’s third sample-return mission. Hayabusa returned 1,500 particles from asteroid Itokawa in 2010. Hayabusa2 followed with 5.4 grams of material from asteroid Ryugu in 2020. Those missions demonstrated the demanding chain of operations required to retrieve material from a small body and deliver it safely to Earth.
NASA also brings relevant experience. Its OSIRIS-REx mission returned 121.6 grams of material from asteroid Bennu in 2023. The United States has separately returned 382 kilograms of lunar rocks through the Apollo program, retrieved solar-wind samples on Genesis, and recovered comet dust through Stardust.
Each target is different, and prior successes do not make MMX routine. But the record gives the participating agencies a body of experience in designing collection systems, protecting samples, navigating return trajectories and preparing laboratories to handle material from beyond Earth.
Why the moons of Mars matter
Phobos and Deimos are much smaller than Earth’s Moon, yet their origin could illuminate a major unresolved part of Mars’s history. A captured-asteroid origin would point toward one sequence of gravitational encounters and solar-system migration. A collision-origin explanation would connect the moons more directly with the formation and evolution of Mars itself.
The MMX samples will not automatically settle the debate, but they could provide evidence unavailable through remote sensing alone. Scientists will be able to examine returned material with laboratory techniques that cannot be sent aboard a spacecraft. The value lies in connecting composition and physical properties to models of how the moons formed.
The mission also arrives as sample return becomes an increasingly important method in planetary science. Rather than only photographing or measuring a distant object in place, missions can return carefully collected material for repeated analysis as techniques improve. That approach makes a single flight potentially useful to multiple generations of researchers.
Countdown toward Mars
The immediate milestone is launch. MMX is set to leave Tanegashima early Tuesday morning in Japan, which corresponds to Monday afternoon on the US East Coast. From there, the mission faces a multi-year sequence of travel, Mars-system operations, sampling and the journey home.
For JAXA and its partners, success would add a new chapter to sample-return exploration and place material from a Martian moon in laboratories on Earth. For planetary science, it could bring the origin of Phobos and Deimos closer to an answer.
This article is based on reporting by spacepolicyonline.com. Read the original article.
Originally published on spacepolicyonline.com
