Japan’s Martian Moons Exploration (MMX) mission & payloads

Artist's impression of MMX orbiting Phobos. (Image Credit: JAXA)

Earlier this month, we took a look at the recent developments from JAXA and their European partners with regards to Hayabusa 2 and the MASCOT hopper rover.

In the following days of the successful completion of the MASCOT mission, JAXA issued a joint statement regarding future European collaboration on JAXA’s MMX (Martian Moons eXplorer) mission, which is aiming for launch in the 2024.

The MASCOT rover, which is currently lying dead on asteroid Ryugu after operating for 17 hours, having completed its valiant mission, was developed by CNES and DLR under supervision by JAXA.

After the mission had ended, the three national space agencies released the following statement at IAC 2018 in Bremen:

“In the light of this success, JAXA, CNES, and DLR jointly declare their wish to cooperate on the MMX (Martian Moons eXploration) mission as follows:

MMX is a JAXA led mission to explore Martian moons, Phobos and Deimos, aiming for observation, landing, and sample return.

JAXA, CNES, and DLR have agreed that the rover onboard MMX would be developed through French-German collaboration”.  

This mission will mark the first attempt to collect specimens from the Martian moons since the ill-fated 2011 Russian Fobos-Grunt mission misfired and ended up stranded in LEO, before plunging into the ocean.

If successful, it will be the first mission to retrieve samples from the Martian moon system, and will be one of only a handful of successful sample return missions from astronomical bodies (including Hayabusa 1).


MMX will focus on the Martian moons. The spacecraft itself will make close-up remote sensing and in-situ observations of both moons, and will collect a sample from one of the moons to bring back to Earth, using the rover which will be developed by France (CNES) and Germany (DLR).

Not many details of MMX have been published, but aside from the European collaboration on the rover, we do know that NASA has already selected an instrument to be included on the main spacecraft, as part of its low-cost, high impact Discovery Program.

NASA’s instrument on MMX will be a neutron and gamma-ray spectrometer, which will provide insight into how the two Martian moons were formed.

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“Solving the riddle of how Mars’ moons came to be will help us better understand how planets formed around our Sun and, in turn, around other stars,” said Thomas Zurbuchen, associate administrator for NASA’s Science Mission Directorate (SMD) at Headquarters in Washington.

“International partnerships like this provide high-quality science with high- impact return.”

The spectrometer, named MEGANE (meaning “eyeglasses” in Japanese), will be developed by Johns Hopkins University Applied Physics Laboratory, and will allow MEGANE to observe the elemental composition of Phobos, by measuring the energies of neutrons and gamma-rays emitted from the moon.

“We’ll see the composition of the region from which MMX collects its sample,” said Thomas Statler, program scientist for MMX at NASA Headquarters in Washington. “This will help us better understand what we discover in the laboratory when the mission returns the sample to Earth for analysis.”

In addition to the European rover and the NASA payload, we also know that the following instruments are being considered for the mission:

CMDM (Circum-Martian Dust Monitor)

This instrument will be used for clarifying the dust environment around the Martin moon. By measuring the dust abundance of 10 μm or more in size, the frequency of collision of celestial bodies that generate dust and the phenomenon of dust reintegration on Martian moons will be determined.

CMDM is being developed under the guidance of the Planetary Exploration Research Center, Chiba Institute of Technology, Japan.

“I am extremely excited to be able to participate in the MMX mission” said Masanori Kobayashi of the Chiba Institute of Technology.

“We are aiming to discover the Martian circulation dust that has been theoretically predicted for many years but has not been found yet. Although there is a long way to go before we get to the goal, we try our best.”

MSA (Mass Spectrum Analyzer)

The MSA will clarify the ion environment around the Martian moon and will detect the presence of ice inside the Martian moon, the weathering effect of the Martian moon surface, and the amount of Martian atmosphere dissipation.

MSA is being developed by researchers at Osaka University, Japan.

MacrOmega (Macroscopique Observatoire pour la Minéralogie, l’Eau, le Glaces et l’Activité)

The acronym when translated means “Macroscopic Observatory for Mineralogy, Water, Ice and Activity” and it is a near infrared (NIR) observation device designed to clarify the characteristics of minerals constituting the Martian moon. MacrOmega will use its spectroscope to measure NIR emissions up to the 4 μm wavelength band. This information will be used to determine the distribution of water related substances and organic matter over the whole moon, and will aid the selection of sampling locations.

It is another European venture and will be developed by the Institut d’Astrophysique Spatiale,France.

LIDAR (Light Detection and Ranging)

The LIDAR instrument will be used to observe the shape of the Martian moon surface. The surface altitude and albedo (diffuse reflected solar radiation) distribution will be derived by measuring the time until the reflected laser light returns to the spacecraft. It’s basically radar, but with light.

This project is also being developed by the Chiba Institute of Technology, Japan.

OROCHI (Optical RadiOmeter composed of CHromatic Imagers)

OROCHI is a wide angle camera designed to observe the topography and material compositions on the Martian moon surface. It can take images of visible light reflected from the Martian moon’s surface at multiple wavelengths to identify hydrated materials and organic matter.

TENGOO (TElescopic Nadir imager for GeOmOrphology)

The TENGOO instrument is a telescopic (narrow angle) camera for observing the detailed terrain on the surface of the Martian moon. It can capture surface images with a special resolution of about 40cm and obtain information on the distribution of different materials that correspond to the collected samples. It will also be used for reconnaissance of the of the proposed sample site.

Both OROCHI and TENGOO are being developed by Rikkyo University, Japan.

The sample sites have not yet been determined. Indeed, the decision to land on Phobos or Deimos has not yet been made.

JAXA and the international partners are currently discussing where samples should be taken from. Remote sensing data obtained by the spacecraft instrumentation will be used to determine the sampling locations once it arrives at the Martian moon, much in the same way that Hayabusa 2 was used to determine landing sites for MASCOT.

Soon enough we shall know the nature of the Martian moon compositions, including information on the structural composition. In fact, scientists are still unsure of whether the moons are solid, or just huge rubble piles.

One thing is for sure. This mission is going to be very rich in science and discovery!



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