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NASA is contributing to JAXA's Martian Moons eXploration (MMX) mission, which launched October 19, 2025, to study Mars' moons Phobos and Deimos and return a sample from Phobos to Earth by 2031. NASA is providing the MEGANE spectrograph to analyze the moon's elemental composition, a pneumatic sampler technology, Deep Space Network support, and will curate approximately 15% of the returned sample. The mission aims to determine whether these moons formed from a massive impact on Mars or are captured asteroids, which will provide insights into the early solar system and how inner planets acquired water and organic compounds.
Why it matters
Understanding the origin of Mars' moons will illuminate the early history of the inner solar system, including how Earth and neighboring planets may have obtained their water and organic materials. The returned samples will provide decades of research opportunities and support NASA's preparation for future human missions to Mars.
Understand the Science
NASA is playing an important role in JAXA’s (Japan Aerospace Exploration Agency) MMX (Martian Moons eXploration) mission, to advance our understanding of Mars’ moons and build on the agency’s long history of exploring the Red Planet.
The mission aims to characterize and determine the origin of Mars’ moons Phobos and Deimos and deliver a sample of Phobos to Earth. The MMX spacecraft is targeting launch from JAXA’s Tanegashima Space Center in Japan at 3:41 p.m. EDT on Monday, Oct. 19 (4:41 a.m. JST on Tuesday, Oct. 20).
“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,” said Nicky Fox, associate administrator, Science Mission Directorate, NASA Headquarters in Washington. “The NASA-JAXA sample curation partnership is extremely valuable, and I am proud that NASA Science is supporting MMX sample curation and will be sharing portions of these samples for study as we continue to expand humanity’s understanding of the universe for the benefit of all.”
NASA’s contributions to the mission include the Mars-moon Exploration with Gamma rays and Neutrons (MEGANE) spectrograph instrument, the Pneumatic Sampler (P-Sampler) technology demonstration, and communications and navigation support from the agency’s Deep Space Network, as well as funding United States scientists participating on the MMX science team.
Scientists have long debated the origin of Mars’ two moons. The data and samples collected by the MMX mission will help answer essential questions about the origins of these moons and the history of the solar system.
“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,” said Tom Statler, MMX program executive and program scientist at NASA Headquarters. “Having the answer will help illuminate that early era when Earth and the other inner planets may have been acquiring much of their water and organic compounds.”
The MEGANE (pronounced meh-GAH-nay, the Japanese word for eyeglasses) spectrograph will help scientists “see” what Phobos is made of by measuring neutrons and gamma rays emitted from the moon’s surface and determining its chemical elemental composition, which will provide important clues about its origin.
Mounted on one of the spacecraft’s landing legs, the P-Sampler is designed to collect a ground sample from Phobos. The system gathers surface material using bursts of high-pressure nitrogen gas, complementing JAXA’s C-Sampler, which will extract cores from a few inches deeper. NASA will obtain and curate about 15% of the total returned sample at the agency’s Johnson Space Center Astromaterials Lab in Houston, making it available for research for decades.
Another key part of NASA’s contribution to MMX is its scientific partnership with JAXA. NASA-supported researchers are working alongside international colleagues to help reveal the story of Phobos and will use mission data and returned samples to uncover new clues about the moon’s origin and the evolution of the Mars system.
The MMX spacecraft will arrive at Mars in August 2027 to begin its survey of the Red Planet’s two moons. After surveying Phobos in detail, the spacecraft will collect a sample of the moon’s surface no earlier than December 2028 and deliver it to Earth in 2031.
The MEGANE instrument was developed by the Johns Hopkins Applied Physics Laboratory. Honeybee Robotics, a Blue Origin company, developed the spacecraft’s pneumatic sampler mechanism. NASA’s contributions to the MMX mission were developed under the agency’s Discovery Program. The Discovery Program is managed by NASA’s Marshall Space Flight Center in Huntsville, Alabama, for the agency’s Science Mission Directorate in Washington.
For more information about the MMX mission, visit:
https://science.nasa.gov/mission/mmx
Karen Fox / Alana Johnson
Headquarters, Washington
240-285-5155 / 202-672-4780
karen.c.fox@nasa.gov / alana.r.johnson@nasa.gov
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Source: NASA to Help Unlock Mysteries of Mars’ Moons in Upcoming Mission