Martian Moons eXploration (MMX)
An artist's concept of Mars Moons eXploration (MMX) spacecraft
Mission typeSample-return mission
Mission duration5 years (planned)
Spacecraft properties
Launch massPropulsion module: 1800 kg
Exploration module: 150 kg
Return module: 1050 kg[2]
MMX Rover: 30 kg
Start of mission
Launch date2026 (planned)[3]
Launch siteTanegashima, LA-Y
ContractorMitsubishi Heavy Industries
Phobos lander
Landing date2027 (planned)[3]
Return launch2031 (planned)[3]
Sample mass≥10 g (0.35 oz)[4]
TElescopic Nadir imager for GeOmOrphology (TENGOO)
Optical RadiOmeter composed of CHromatic Imagers (OROCHI)
Light Detection and Ranging (LIDAR)
MMX InfraRed Spectrometer (MIRS)
Mars-moon Exploration with GAmma rays and NEutrons (MEGANE)
Circum-Martian Dust Monitor (CMDM)
Mass Spectrum Analyzer (MSA)

Martian Moons eXploration (MMX) is a robotic space probe set for launch in 2026 to bring back the first samples from Mars' largest moon Phobos.[3][5] Developed by the Japan Aerospace Exploration Agency (JAXA) and announced on 9 June 2015, MMX will land and collect samples from Phobos once or twice, along with conducting Deimos flyby observations and monitoring Mars's climate.[6]

The mission aims to provide key information to help determine whether the Martian moons are captured asteroids or the result of a larger body hitting Mars. JAXA and other Japanese government officials officially approved the MMX project to proceed into development on 19 February 2020, according to a post on JAXA's website.[1]


Phobos, the largest moon of Mars

The spacecraft will enter orbit around Mars, then transfer to Phobos,[7] and land once or twice and gather sand-like regolith particles using a simple pneumatic system.[8] The lander mission aims to retrieve a minimum 10 g (0.35 oz) of samples.[4][9] The spacecraft will then take off from Phobos and make several flybys of the smaller moon Deimos before sending the Return Module back to Earth, arriving in 2031.[3][10][7]

The total launch mass is 4000 kg including 1900 kg of propellant.[11] The mission architecture uses three modules: Propulsion module (1800 kg), Exploration module (150 kg) and the Return module (1050 kg).[2] With the mass of Deimos and Phobos being too small to capture a satellite, it is not possible to orbit the Martian moons in the usual sense. However, orbits of a special kind, referred to as quasi-satellite orbits (QSO), can be sufficiently stable to allow many months of operations in the vicinity of the moon.[2][12][13]

The mission leader is Yasuhiro Kawakatsu.[14]

International collaboration

NASA, ESA, and CNES[15] are also participating in the project, and will provide scientific instruments.[16][17] 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),[18][19] CNES the Near IR Spectrometer (NIRS4/MacrOmega).[9][20] CNES is also contributing expertise in flight dynamics to plan the mission's orbiting and landing manoeuvres.[8]

Development and testing of key components, including the sampler, is ongoing.[21] As of December 2023, MMX is scheduled to be launched in 2026, and will return to Earth five years later in 2031.[10]

The probe and rover payloads

The scientific payloads

MMX will have seven scientific instruments:[22]

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.[23]

The Gravity GradioMeter (GGM), Laser-Induced Breakdown Spectroscope (LIBS), Mission Survival Module (MSM) were proposed as additional instruments.[24]

The IDEFIX rover

Following a study by the French CNES space agency,[8] it was decided that the spacecraft will deliver a small rover provided by CNES and the German Aerospace Center (DLR). IDEFIX[25][26] is a rover weighing less than 30 kg, and is named after Idéfix, the French name for Dogmatix, Obelix' dog in the French comic Asterix.

It will be equipped with cameras, a radiometer, and a Raman spectrometer for in-situ surface exploration of the Martian moon.[27]

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.[citation needed]


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.[28] [29] 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.[30] 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.[31] 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][10][7]

See also


  1. ^ a b "Phobos sample return mission enters development for 2024 launch". Spaceflight Now. 20 February 2020. Retrieved 7 March 2021.
  2. ^ a b c Japanese mission of the two moons of Mars with sample return from Phobos Hirdy Miyamoto, University of Tokyo 2016
  3. ^ a b c d e f "MMX - Martian Moons eXploration". JAXA. 26 December 2023. Retrieved 26 December 2023.
  4. ^ a b Gravity both too strong and too weak: landing on the Martian moons JAXA News 31 August 2017
  5. ^ "JAXA plans probe to bring back samples from moons of Mars". The Japan Times. 10 June 2015.
  6. ^ "Observation plan for Martian meteors by Mars-orbiting MMX spacecraft". 10 June 2016. Retrieved 23 March 2017.
  7. ^ a b c NASA confirms contribution to Japanese-led Mars mission Stephen Clark, Spaceflight Now 20 November 2017
  8. ^ a b c How to find the best samples on a moon: Building relationships and solving engineering challenges in France JAXA News 4 December 2017
  9. ^ a b Fujimoto, Masaki (11 January 2017). "JAXA's exploration of the two moons of Mars, with sample return from Phobos" (PDF). Lunar and Planetary Institute. Retrieved 23 March 2017.
  10. ^ a b c "Japan to Delay Mars Moon Exploration by 2 Years to 2026". Yomiuri Shimbun. 6 December 2023. Retrieved 26 December 2023.
  11. ^ [1]
  12. ^ Quasi-Satellite Orbits around Deimos and Phobos motivated by the DePhine Mission Proposal Sofya Spiridonova, Kai Wickhusen, Ralph Kahle, and Jürgen Oberst; DLR, German Space Operations Center, Germany 2017
  13. ^ Orbit Maintenance of Quasi-Satellite Trajectories via Mean Relative Orbit Elements Nicola Baresi, Lamberto Dell'Elce, Josué Cardoso dos Santos, and Yasuhiro Kawakatsu International Astronautical Congress, Bremen, Germany, 2018
  14. ^ Kawakatsu Lab Homepage Deep Space Mission Design Laboratory (DSMDL) Institute of Space and Astronautical Science (ISAS)/JAXA, 2017
  15. ^ "Coopération spatiale entre la France et le Japon Rencontre à Paris entre le CNES et la JAXA-ISAS" (PDF) (Press release) (in French). CNES. 10 February 2017. Retrieved 23 March 2017.
  16. ^ "ISASニュース 2017.1 No.430" (PDF) (in Japanese). Institute of Space and Astronautical Science. 22 January 2017. Retrieved 23 March 2016.
  17. ^ Green, James (7 June 2016). "Planetary Science Division Status Report" (PDF). Lunar and Planetary Institute. Retrieved 23 March 2017.
  18. ^ "NASA confirms contribution to Japanese-led Mars mission". Spaceflight Now. 20 November 2017. Retrieved 8 March 2021.
  19. ^ Back to the Red Planet Archived 27 March 2018 at the Wayback Machine Johns Hopkins APL 17 November 2017
  21. ^ "ISASニュース 2016.7 No.424" (PDF) (in Japanese). Institute of Space and Astronautical Science. 22 July 2016. Retrieved 23 March 2017.
  22. ^ "MMX Science". Japanese Aerospace Exploration Agency. Archived from the original on 15 February 2021. Retrieved 14 September 2020.
  23. ^ "8K Camera on the Martian Moons eXploration (MMX) Spacecraft to Take Ultra High Definition Images of Mars". Japan Aerospace Exploration Agency.
  24. ^ Ozaki, Masanobu; Shiraishi, Hiroaki; Fujimoto, Masaki (5 January 2017). "火星衛星探査計画(MMX)の科学観測装置" (in Japanese). JAXA. Retrieved 12 July 2017.
  25. ^ "Rover". Mmx (in French). 3 November 2020. Retrieved 6 September 2023.
  26. ^ "Rover auf der Zielgeraden zum Marsmond Phobos". (in German). Retrieved 6 September 2023.
  27. ^ "DLR Press Portal". Retrieved 16 August 2019.
  28. ^ Hiroki Kato, Yasutaka Satou, Kent Yoshikawa, Masatsugu Otsuki, Hirotaka Sawada, Takeshi Kuratomi, and Nana Hidaka, "Subsurface Sampling Robot for Time-limited Asteroid Exploration," 2020 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS), Las Vegas, NV, USA, 2020, pp. 1925-1932, doi: 10.1109/IROS45743.2020.9340645.
  29. ^ 90 minutes on the clock! Discussing the MMX sampling device with JAXA robotic specialist Hiroki Kato, JAXA News 7 June 2022
  30. ^ Preparing for the unexpected: a second way to sample a moon Yasutaka Satou, JAXA News 25 October 2017
  31. ^ Kuramoto, Kiyoshi; Kawakatsu, Yasuhiro; Fujimoto, Masaki; Araya, Akito; Barucci, Maria Antonietta; Genda, Hidenori; Hirata, Naru; Ikeda, Hitoshi; Imamura, Takeshi; Helbert, Jörn; Kameda, Shingo; Kobayashi, Masanori; Kusano, Hiroki; Lawrence, David J.; Matsumoto, Koji (20 January 2022). "Martian moons exploration MMX: sample return mission to Phobos elucidating formation processes of habitable planets". Earth, Planets and Space. 74 (1): 12. doi:10.1186/s40623-021-01545-7. ISSN 1880-5981.