Japan begins its bid to bring back material from Phobos
Japan’s Martian Moons eXploration mission, known as MMX, has launched on a journey to Mars that is intended to return samples from the moon Phobos to Earth in 2031. The Japan Aerospace Exploration Agency mission lifted off aboard a Mitsubishi Heavy Industries H3 rocket from the Tanegashima launch site.
MMX is not designed to land on Mars itself. Instead, it will travel to the Martian system to examine both of the planet’s small moons, Phobos and Deimos. Its central objective is to land on Phobos, gather material and carry it back to Earth. If successful, the mission would return the first samples from a moon other than Earth’s.
The launch marks the opening stage of a mission planned to last about five years. MMX is expected to arrive at Mars in August 2027. A landing on Phobos is scheduled no earlier than December 2028, with the returned material due to land in Australia in 2031.
Why Phobos matters
Phobos and Deimos remain a scientific puzzle. Phobos, the larger moon, is about 22 kilometers across; Deimos is about 12 kilometers across. Researchers are trying to determine whether the moons are captured asteroids or material thrown into orbit after an ancient collision involving Mars.
The asteroid belt lies between Mars and Jupiter, making capture a plausible explanation for objects near Mars. But the moons’ nearly circular orbits and their alignment with Mars’s equator are also consistent with a different origin: debris from a major impact on Mars that eventually collected into moons.
Material collected directly from Phobos could help distinguish between those possibilities. If the moon is a captured asteroid, its samples may preserve a history distinct from Mars. If it formed from ejecta, the samples may contain evidence tied to Mars and the impact that created the debris. The mission is therefore aimed at a question about the formation and evolution of the Martian system, not simply a new destination for sample return.
A mission built around close operations near Mars
After reaching Mars, MMX is planned to enter a quasi-satellite orbit, or QSO. That trajectory is intended to support observations of Phobos and Deimos and enable operations leading to a landing on Phobos. The spacecraft will study both moons while focusing its sample-return work on the larger one.
The mission also carries an international rover contribution. Germany’s DLR and France’s CNES developed Idefix, a four-wheeled rover with a mass of 25 kilograms. The partners previously worked together on the MASCOT hopper flown to asteroid Ryugu on JAXA’s Hayabusa2 mission. MASCOT operated on Ryugu for 17 hours in 2018.
That heritage matters because JAXA has already completed two asteroid sample-return missions. Hayabusa returned material from Itokawa in 2010, and Hayabusa2 returned material from Ryugu in 2020. Both missions required operations around bodies with extremely weak gravity, experience that can inform the difficult navigation and surface work needed at Phobos.
From asteroid returns to a Martian-moon return
MMX extends Japan’s sample-return record to a more distant and complex target. Returning material from Phobos requires a launch from Earth, a cruise to Mars, operations around the Martian moons, collection at Phobos and a journey home. The planned 2031 recovery in Australia follows the recovery locations used for Japan’s previous asteroid-return capsules.
The mission’s value will depend on both the quality of the samples and the context created by the spacecraft’s observations of the two moons. Its findings could clarify whether Phobos and Deimos share an origin, whether their material is more asteroid-like or Mars-related, and how the Martian system changed over time.
For now, MMX is en route. Its launch begins a multi-year attempt to turn one of Mars’s closest and most enigmatic companions into a source of laboratory evidence on Earth.
This article is based on reporting by spacepolicyonline.com. Read the original article.
Originally published on spacepolicyonline.com
