Martian Moons eXploration

The spacecraft will enter orbit around Mars before transferring to Phobos, where it will land once or twice and collect regolith samples using a pneumatic sampling system.^[9] The mission is designed to return at least 10 grams (0.35 oz) of material from the moon's surface.^[4][10] After departing Phobos, the spacecraft will conduct several flybys of Deimos before releasing a return capsule for Earth, with sample return planned for 2031.^[3][11][12]

The spacecraft has a total launch mass of approximately 4,000 kilograms (8,800 lb), including about 1,900 kilograms (4,200 lb) of propellant.^[13] The spacecraft consists of three major elements: a 1,800-kilogram (4,000 lb) propulsion module, a 150-kilogram (330 lb) exploration module, and a 1,050-kilogram (2,310 lb) return module.^[14]

Because Phobos and Deimos have insufficient mass to support conventional satellite orbits, MMX will operate in quasi-satellite orbits (QSOs), a class of trajectories that can remain stable for extended periods while staying in close proximity to the moons.^[14][15][16]

The mission is led by Yasuhiro Kawakatsu.^[17]

MMX is led by JAXA, with participation from NASA, France's CNES, Germany's DLR, and the European Space Agency (ESA), who are providing scientific instruments.^[18][19]

NASA will contribute a neutron and gamma-ray spectrometer called MEGANE (an acronym for Mars-moon Exploration with GAmma rays and NEutrons, which also means "eyeglasses" in Japanese).^[12][20] CNES will provide the Near IR Spectrometer (NIRS4/MacrOmega).^[10][21] CNES is also contributing expertise in flight dynamics to plan the mission's orbiting and landing manoeuvres.^[9]

Development and testing of key components, including the sampler, is ongoing.^[22] As of December 2023, MMX is scheduled to be launched in 2026, and will return to Earth five years later in 2031.^[11]

ESA will provide deep space communication equipment: a transponder and power amplifier, and will provide ground station support from the Estrack network.^[23]

The sample-return capsule will land in Australia.^[23][24][25]

MMX will have seven scientific instruments:^[26]

• TENGOO – TElescopic Nadir imager for GeOmOrphology, a narrow field camera for detailed terrain study^[27]
• OROCHI – Optical RadiOmeter composed of CHromatic Imagers, a wide field visible light camera
• LIDAR – Light Detection and Ranging, uses a laser to reflect light from the moon's surface, to study surface altitude and albedo
• MIRS – MMX InfraRed Spectrometer, a near-infrared observation device for characterizing the minerals that make up the moons of Mars. Developed in partnership with CNES, France^[28]
• MEGANE – (MEGANE means "eyeglasses" in Japanese) Mars-moon Exploration with GAmma rays and NEutrons, a gamma-ray and neutron spectrometer developed by NASA, Johns Hopkins Applied Physics Laboratory, and Lawrence Livermore National Laboratory^[29]
• CMDM – Circum-Martian Dust Monitor, a dust counting device for characterizing the environment around the Martian moons
• MSA – Mass Spectrum Analyzer, an instrument to study the ion environment around Mars

JAXA will partner with the Japan Broadcasting Corporation (NHK) to develop the "Super Hi-Vision Camera" which combines a 4K and 8K camera, making it the first time that Mars will be imaged in 8K resolution. Images will be regularly transmitted back to Earth with flight data, in order to recreate MMX exploration around Mars and its moons. The original image data will be stored in a recording device in MMX's return capsule and brought back to Earth as part of the sample-return portion of the mission.^[30]

The Gravity GradioMeter (GGM), Laser-Induced Breakdown Spectroscope (LIBS), Mission Survival Module (MSM) were proposed as additional instruments.^[31]

• 
  A scale model of the spacecraft
• 
  Older design of the MMX spacecraft
• 
  U.S. and Japanese team members with the gamma-ray spectrometer portion of the MEGANE instrument at Johns Hopkins APL.

Following a study by the French CNES space agency,^[9] it was decided that the spacecraft will deliver a small rover provided by CNES and the German Aerospace Center (DLR). IDEFIX^[32][33][34] is a rover weighing less than 30 kg, and is named after Idéfix, the French name for Dogmatix, Obelix's dog in the French comic Asterix. The name Idefix (without acute accent) is also used for the character in the German translation. Besides its native France the Asterix series has been particularly successful in Germany — out of 350 million comic books sold worldwide by 2013, 130 million were in the French original while 120 million were in German.^[35]

It will be equipped with cameras, a radiometer, and a Raman spectrometer for in-situ surface exploration.^[36] The instruments are: two navigation cameras (NavCams), two cameras (WheelCams) "that will observe the interactions of the back and front wheels with the regolith", a Raman spectrometer (RAX) and a miniaturized radiometer (miniRad).^[37]

Its objectives are to touch the surface of Phobos, to check the behaviour of the surface under mechanical actions and to relay this information to Earth. It must also demonstrate that it is possible to use wheeled locomotion on a body with such low gravity. Finally, it will take measurements in situ, observing the ground of Phobos at a resolution of 100 μm, and moving around on it.^[37]

MMX's sampler is equipped with two sampling methods: the Coring Sampler (C-SMP) to gain regolith at depths deeper than 2 cm from the Phobos surface, and the Pneumatic Sampler (P-SMP) for samples from the Phobos surface. The robotic arm will collect regolith from the ground by shooting the C-SMP mechanism. The C-SMP mechanism is designed to rapidly perform subsurface sampling to collect over 10 grams of the regolith. It is equipped with an ejecting actuator that uses a special shape memory alloy, SCSMA.^[38][39] P-SMP is installed close to the footpad of the landing leg, and uses an air gun to puff pressurized gas, pushing about 10 grams of soil into the sample container.^[40] Both C-SMP and P-SMP can collect samples quickly because the entire sampling procedure is scheduled to be performed in only 2.5 hours.

After taking a sample, the robotic arm will transfer both C-SMP and P-SMP canisters to the sample return capsule.^[41] The spacecraft will then make several flybys of the smaller moon Deimos before carrying the Sample Return Capsule back to Earth, arriving in 2031.^[3][11][12]

A study published in 2026 claims based on realistic constrains that the mission has clear opportunities to discover organic residues.^[42]

• Phobos program
• Fobos-Grunt
• Mars sample-return mission

• Ogohara, Kazunori; Nakagawa, Hiromu; Aoki, Shohei; Kouyama, Toru; Usui, Tomohiro; Terada, Naoki; Imamura, Takeshi; Montmessin, Franck; Brain, David; Doressoundiram, Alain; Gautier, Thomas; Hara, Takuya; Harada, Yuki; Ikeda, Hitoshi; Koike, Mizuho; Leblanc, François; Ramirez, Ramses; Sawyer, Eric; Seki, Kanako; Spiga, Aymeric; Vandaele, Ann Carine; Yokota, Shoichiro; Barucci, Antonella; Kameda, Shingo (3 January 2022). "The Mars system revealed by the Martian Moons eXploration mission". Earth, Planets and Space. 74 (1) 1. Bibcode:2022EP&S...74....1O. doi:10.1186/s40623-021-01417-0. hdl:2433/299883. ISSN 1880-5981.
• Fujiya, Wataru; Furukawa, Yoshihiro; Sugahara, Haruna; Koike, Mizuho; Bajo, Ken-ichi; Chabot, Nancy L.; Miura, Yayoi N.; Moynier, Frederic; Russell, Sara S.; Tachibana, Shogo; Takano, Yoshinori; Usui, Tomohiro; Zolensky, Michael E. (1 June 2021). "Analytical protocols for Phobos regolith samples returned by the Martian Moons eXploration (MMX) mission". Earth, Planets and Space. 73 (1): 120. Bibcode:2021EP&S...73..120F. doi:10.1186/s40623-021-01438-9. ISSN 1880-5981. PMC 8550573.