Martian Moons Exploration

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Martian Moons Exploration (MMX)
Mmxspacecraft 0.jpg
Mission typeSample return
OperatorISAS / JAXA
Mission duration~5 years (planned)
Spacecraft properties
Dry massPropulsion module: 1,800 kg
Exploration module: 150 k
Return module: 1,050 kg[1]
Start of mission
Launch dateSeptember 2024 (planned)[2]
Phobos lander
Landing dateMarch 2025[2]
Return launchAugust 2028[2]
Sample mass≥10 g (0.35 oz)[3]

The Martian Moons Exploration (MMX) is a robotic space probe set for launch in 2024 to bring back the first samples from Mars' largest moon Phobos.[2][4] Developed by the Japanese Aerospace Exploration Agency (JAXA) and announced in 9 June 2015, MMX will land and collect samples from Phobos once or twice, along with conducting Deimos flyby observations and monitoring Mars' climate.[5][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.


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.[3][9] The spacecraft will then take off from Phobos and make several flybys of the smaller moon Deimos before sending the Sample Return Capsule back to Earth, arriving in July 2029.[7][2]

The mission architecture uses three modules: propulsion module (1,800 kg), exploration module (150 kg) and the return module (1,050 kg).[1] 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, can be sufficiently stable to allow many months of operations in the vicinity of the moon.[1][10]

The mission leader is Yasuhiro Kawakatsu.

International collaboration[edit]

NASA, ESA, and CNES[11] are also participating in the project, and will provide scientific instruments.[12][13] The U.S. 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),[7][14] and France (CNES) the Near IR Spectrometer (NIRS4/MacrOmega).[9][15] France 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.[16] As of 2018, MMX is scheduled to be launched in 2024, and will return to Earth five years later.[9]

Scientific payload[edit]

The scientific payload consists on Japanese and international contributions. They will be powered by solar arrays.[2]

  • Gamma ray and Neutron Spectrometer (MEGANE) - developed by NASA, USA
  • Wide Angle Multiband Camera (WAM)
  • Near-Infrared Spectrometer (MacrOmega) - developed by CNES, France.
  • Optical Radiometer composed of Chromatic Imagers (OROCHI)
  • Telescopic Nadir Imager for Geomorphology (TENGOO)
  • Light Detection and Ranging (LIDAR)
  • Circum-Martian Dust Monitor (CMDM)
  • Mass Spectrum Analyzer (MSA)

Additionally, the Gravity GradioMeter (GGM), Laser-Induced Breakdown Spectroscope (LIBS), Mission Survival Module (MSM) were proposed as additional instruments.[17]

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). The rover will be equipped with cameras, a radiometer, and a Raman spectrometer for in-situ surface exploration of the Martian moon.[18]


For sample collection, the mission opted to use an air gun to puff pressurised gas, pushing about 10 grams of soil into the sample container.[19] The spacecraft will then take off from Phobos and make several flybys of the smaller moon Deimos before sending the Sample Return Capsule back to Earth, arriving in July 2029.[7][2]

See also[edit]

Proposed missions to Mars' moons


  1. ^ a b c Japanese mission of the two moons of Mars with sample return from Phobos. Hirdy Miyamoto, University of Tokyo. 2016.
  2. ^ a b c d e f g MMX Homepage. JAXA, 2017
  3. ^ a b Gravity both too strong and too weak: landing on the Martian moons. JAXA News. 31 August 2017
  4. ^ "JAXA plans probe to bring back samples from moons of Mars". 10 June 2015 – via Japan Times Online.
  5. ^ "Observation plan for Martian meteors by Mars-orbiting MMX spacecraft" (PowerPoint). June 10, 2016. Retrieved 2017-03-23.
  6. ^ "A giant impact: Solving the mystery of how Mars' moons formed". ScienceDaily. July 4, 2016. Retrieved 2017-03-23.
  7. ^ a b c d NASA confirms contribution to Japanese-led Mars mission. Stephen Clark, Space Flight 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 c Fujimoto, Masaki (January 11, 2017). "JAXA's exploration of the two moons of Mars, with sample return from Phobos" (PDF). Lunar and Planetary Institute. Retrieved 2017-03-23.
  10. ^ Quasi-Satellite Orbits around Deimos and Phobos motivated by the DePhine Mission Proposal. (PDF) Sofya Spiridonova, Kai Wickhusen, Ralph Kahle, and Jürgen Oberst. DLR, German Space Operations Center, Germany. 2017.
  11. ^ "Coopération spatiale entre la France et le Japon Rencontre à Paris entre le CNES et la JAXA-ISAS" (PDF) (Press release) (in French). CNES. February 10, 2017. Retrieved March 23, 2017.
  12. ^ "ISASニュース 2017.1 No.430" (PDF) (in Japanese). Institute of Space and Astronautical Science. 22 January 2017. Retrieved 2016-03-23.
  13. ^ Green, James (June 7, 2016). "Planetary Science Division Status Report" (PDF). Lunar and Planetary Institute. Retrieved 2017-03-23.
  14. ^ Back to the Red Planet. Johns Hopkins APL. 17 November 2017.
  16. ^ "ISASニュース 2016.7 No.424" (PDF) (in Japanese). Institute of Space and Astronautical Science. 22 July 2016. Retrieved 2017-03-23.
  17. ^ 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 2017-07-12.
  18. ^ DLR. "DLR Press Portal". DLR Portal. Retrieved 2019-08-16.
  19. ^ Preparing for the unexpected: a second way to sample a moon. Yasutaka Satou, JAXA News. 25 October 2017.