The Japanese MMX (Martian Moons eXploration) mission, led by the Japan Aerospace Exploration Agency (JAXA), was successfully launched on October 20, 2026 (October 19, 2026, in Paris) aboard an H3 launch vehicle from the Tanegashima Space Center in Japan.
Heading for Phobos and Deimos, Mars’s two moons, MMX carries, among other things, the Franco-German mobile robot Idefix®, developed jointly by CNES and the German space agency, the DLR, as well as MIRS, a near-infrared imaging spectrometer developed under the leadership of the Paris Observatory-PSL at LIRA (Laboratory for Instrumentation and Research in Astrophysics—CNRS/Paris Observatory-PSL/Sorbonne University/Paris Cité University) and CNES. CNES is also contributing to the mission through another aspect : flight dynamics.
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Gaining a better understanding of the origin of Phobos and Deimos
The primary objective of the MMX mission is to gain a better understanding of the origin of Phobos and Deimos. The mission will also study the Martian atmosphere using onboard scientific instruments. After a journey of nearly a year, the probe will reach Mars in 2027 and spend three years in its vicinity. Phobos is the main celestial body under study and will be the subject of several observation phases, which will, among other things, help prepare for the collection of samples from its surface. At least 10 grams of material will be gathered and brought back to Earth. During this phase, Idefix® will also be deployed on Phobos for a mission scheduled to last 100 actual operating days (excluding the probe’s landing maneuvers). MMX will then head toward Deimos, which it will observe during a series of flybys, before beginning its return journey. In 2031, a capsule containing the samples from Phobos will arrive on Earth.
French expertise in flight dynamics
Cooperation with JAXA regarding flight dynamics began as early as 2017. CNES teams have been involved in designing and validating the probe’s trajectories around Phobos, including several low-altitude orbits to be used during the mission. They are also contributing to the probe’s navigation and orbit determination, as well as to the understanding of Phobos’s dynamics—specifically its ephemerides and gravity field. This collaboration draws on the expertise CNES gained during the proximity phases of missions to explore small celestial bodies, most notably Rosetta/Philae and Hayabusa-2/MASCOT. This expertise, along with that of the Space Geodesy Research Group (GRGS), will support the MMX mission throughout its flight operations.
MIRS : a valuable French-made instrument
The second component of the French contribution is MIRS (MMX InfraRed Spectrometer), a near-infrared imaging spectrometer installed on the MMX probe. During observations of Phobos and flybys of Deimos, the instrument will analyze light reflected from their surfaces to determine their mineralogical composition and, in particular, to search for the presence of water or organic matter.
CNES acts as the contracting authority for MIRS, contributing to its development alongside the Paris Observatory-PSL within LIRA (Laboratory for Instrumentation and Research in Astrophysics—a joint unit involving CNRS, Paris Observatory-PSL, Sorbonne University, and Université Paris Cité), which serves as the prime contractor. Several other CNRS laboratories are also involved in the instrument : the Bordeaux Astrophysics Laboratory (CNRS/University of Bordeaux), the Laboratory for Atmospheres and Space Observations (CNRS/Sorbonne University/Versailles Saint-Quentin University), the Midi-Pyrénées Observatory (CNRS/University of Toulouse/Météo France/IRD/CNES), and the Research Institute in Astrophysics and Planetology (CNES/CNRS/University of Toulouse).
In total, around twenty scientists from nine French laboratories are associated with MIRS. This group also includes the Marseille Astrophysics Laboratory (Aix-Marseille University/CNES/CNRS), the Institute of Planetology and Astrophysics of Grenoble (CNRS/UGA), the Paris Institute of Earth Physics (CNRS/Université Paris Cité), the Dynamic Meteorology Laboratory (CNRS/École Polytechnique/ENS-PSL/Sorbonne University), and the Côte d’Azur Observatory (CNRS/Université Côte d’Azur). Furthermore, CNES has developed the MIRS ground segment and will oversee instrument operations throughout the mission, while LIRA—in collaboration with the Laboratory of Planetology and Geosciences (CNRS/Nantes University/Le Mans University/University of Angers)—will be responsible for the exploitation of scientific data.
Idefix® : Scout, Demonstrator, and Scientific Explorer
Finally, the last component concerns the French contribution to Idefix®—a rover developed jointly by CNES and the German space agency, DLR. Weighing less than 25 kg, it will be deployed on the surface of Phobos, where it will serve three functions : scout, demonstrator, and scientific explorer.
First, Idefix® will characterize the properties of the surface, providing JAXA with information useful for preparing the landing of the MMX spacecraft. It will also demonstrate the feasibility of moving by rolling across a celestial body where gravity is nearly 2,000 times weaker than on Earth. Finally, the rover will conduct direct measurements on the surface and observe the terrain of Phobos at a resolution of up to 100 micrometers.
Its nominal mission will last 100 operational days, with the goal of traveling up to 100 meters. Operations will be managed alternately by teams from CNES and DLR. The Côte d’Azur Observatory (OCA) is responsible for the scientific coordination of the Idefix® rover on the French side, while ISAE-SUPAERO and the Marseille Astrophysics Laboratory (LAM) are in charge of the scientific utilization of its cameras.
France-Japan : A Fruitful Space Partnership
The participation of CNES in the MMX mission is part of a partnership between Japan and France that has already led to numerous successes in space. Among the most ambitious missions are Juice and BepiColombo—developed within the framework of the European Space Agency (ESA)—as well as Hayabusa2, which was carried out through bilateral cooperation.