Japan Launches MMX Mission to Collect Samples From Phobos

Japan has launched a spacecraft on a mission to investigate the origins of Mars' two moons and bring material from Phobos back to Earth. The Martian Moons eXploration (MMX) mission, led by the Japan Aerospace Exploration Agency (JAXA), lifted off aboard an H3 rocket from Tanegashima Space Center in southwestern Japan at 3:41 p.m. ET Monday, October 19, 2026, according to CNN. The spacecraft is expected to reach Mars in August 2027, with its samples scheduled to return in 2031.

The mission aims to collect at least 10 grams of material from Phobos, the larger of Mars' two small moons. If successful, it could provide scientists with the first samples directly collected from a Martian moon and potentially deliver material originating on Mars itself.

MMX will also observe Deimos during its journey into the Martian system before concentrating on Phobos. The international project includes scientific contributions from NASA, the European Space Agency, France's National Center for Space Studies and the German Aerospace Center.

Dr. Daniel Glavin, a senior scientist at NASA's Goddard Space Flight Center and a participating scientist on MMX, said the mission addresses a major unresolved question in planetary science.

"This is kind of like one of the major outstanding mysteries of solar system formation, the origin of Phobos and Deimos, so we really do need a mission like MMX to figure this out," said Dr. Daniel Glavin, senior scientist at NASA's Goddard Space Flight Center.

The two moons have been observed by spacecraft orbiting Mars and rovers exploring its surface, but their origins remain uncertain. Scientists are investigating whether they formed from debris following a major impact on Mars or are asteroids captured by the planet's gravity.

Dr. Abigail Fraeman, a research scientist at NASA's Jet Propulsion Laboratory and a participating scientist on MMX, emphasized that existing observations have not resolved the question.

"What are these little space potatoes? We can't explain Phobos or Deimos right now. They shouldn't exist, but they do.

They're super weird, they're super small and they're super puzzling," said Dr. Abigail Fraeman, research scientist at NASA's Jet Propulsion Laboratory.

Fraeman also said current evidence does not fully support either leading explanation.

"None of our data fit either hypothesis correctly," said Fraeman.

The spacecraft will deploy a small rover called Idefix, developed by the German Aerospace Center and France's National Center for Space Studies. The rover is scheduled to reach Phobos in early 2029 and survey the surface to help engineers select a landing site for the spacecraft's sample-collection operations.

Phobos presents unusual engineering challenges because its weak gravity and proximity to Mars create a difficult environment for landing. According to CNN, Idefix is expected to descend from approximately 131 to 328 feet before bouncing across the moon's surface and settling into position.

Once the landing site has been assessed, MMX will use a robotic arm and two sampling devices to gather material. Its scientific instruments will also measure surface characteristics, minerals, chemical elements and space radiation, while two Super Hi-Vision cameras will capture images in 4K and 8K resolution.

Professor Sara Russell of the Natural History Museum, MMX's deputy for sample analysis, said the mission is attempting a feat that has not previously succeeded.

"There hasn't yet been a successful mission to go to Phobos and bring a bit back to Earth," said Professor Sara Russell, deputy for sample analysis on the MMX mission.

Russell described the project as an ambitious undertaking.

"I think this is an incredibly ambitious and fun mission," said Russell.

The planned return capsule will carry a small quantity of collected material to Earth, with a landing scheduled for 2031 in South Australia's Woomera desert. Scientists expect laboratory analysis to help distinguish between the impact-debris and captured-asteroid theories.

Dr. Chrysa Avdellidou of the University of Leicester, who is working with the Japanese mission, said the small sample could still support extensive research.

"It's a very small amount actually," said Dr. Chrysa Avdellidou, a researcher at the University of Leicester.

Avdellidou explained that scientists can conduct meaningful investigations using extremely small quantities of extraterrestrial material.

"However, we can do several studies even on individual grains. You don't need to have kilos back from a surface in order to do science. So it's worth every gram," said Avdellidou.

Russell said laboratory testing could quickly clarify the moons' composition and origin.

"When we get the sample back, we'll be able to look in detail at its chemistry and its mineral composition, and the two hypotheses will produce very distinct results," said Russell.

She added that the chemical evidence could distinguish between the two proposed formation mechanisms.

"It should be pretty much immediately obvious whether it's the product of this dramatic impact or whether it's a captured asteroid. So we'll find that out really quickly," said Russell.

Researchers also hope Phobos contains fragments ejected from Mars by meteorite impacts. Because the moon orbits close to the planet, some Martian material may have become embedded in its surface over time.

Russell said this possibility could expand the mission's scientific value.

"One of the really exciting things is that Phobos is so close to the Mars surface that whenever there's an impact into the Mars surface, little grains might actually become implanted into Phobos itself," said Russell.

She said such material could offer an additional source of information about the Red Planet.

"And that means that the sample we get back may actually contain grains of Mars as well. So it can give us really direct information about the composition and history of Mars," said Russell.

NASA's Perseverance rover has been collecting and storing Martian samples since 2021, but the planned NASA-European Space Agency Mars Sample Return effort was effectively canceled after the US Congress halted its funding. China, meanwhile, plans to launch its own Mars sample-return mission in 2028, with a return targeted for 2031.

Meteorites originating on Mars already reach Earth, but their exposure to terrestrial air, dust, soil and water can contaminate them. Material collected directly from Phobos could therefore offer researchers a different opportunity to study the history and composition of the Martian system.