Unlike Earth, Mars has two moons: Phobos and Deimos. However, comparatively little is known about them, for example how the small, irregularly shaped moons were formed and what they are made of. An international team of scientists now wants to solve these mysteries. Several US explorations and European missions - Mars Express (launched in 2003) and ExoMars Gas Trace Orbiter (launched in 2016) - have already provided data and images from Mars orbit, which have been used to observe the moons. However, there has not yet been a successful landing on one of them. Little is therefore known about their geological, mineralogical and geochemical properties.

Material samples from Phobos for the first time

The MMX space probe from the Japanese space organization JAXA will soon change this: If everything goes as planned, it will examine the two moons of Mars in detail from orbit and collect material samples from Phobos for the first time. It will also carry the MMX rover developed jointly by the German Aerospace Center (DLR) and the French space agency CNES (Centre National des Etudes Spatiales) and set it down on Phobos. The ambitious project is expected to be launched in 2026.

European mission share: the MMX rover IDEFIX

The MMX landing vehicle, called IDEFIX, is to fulfill several tasks on Phobos: Firstly, it is to provide important findings in preparation for the landing of the mother ship. Secondly, it will analyze the surface composition and properties at interesting locations. A total of eight DLR institutes from five locations are contributing to the rover: The Institute of Robotics and Mechatronics is responsible for overall project management and - together with the Institute of Space Systems - for system engineering. In addition, the Institute of Robotics and Mechatronics developed a software pipeline to navigate the rover autonomously on the surface of Phobos. Together, the Institutes of Robotics and Mechatronics and of System Dynamics and Control were responsible for the uprighting and locomotion system of the 25-kilogram rover. The Institute of Software Technology provided support in the software development of the navigation and locomotion system.

Cooperation across national borders

The carbon structure was developed under the direction of the Institute of Lightweight Structures. The Institute of System Dynamics and Control provided extensive simulations on the nature of the Phobos ground and the safe movement of the rover. DLR's rover component was integrated and tested under realistic conditions at the Institute of Space Systems. The DLR Institute of Planetary Research contributed the miniRAD radiometer and the DLR Institute of Optical Sensor Systems the RAX Raman spectrometer. The DLR User Center for Space Experiments (MUSC) in Cologne, together with the University Université Côte d'Azur (France), is the scientific lead for the rover and is responsible for payload management. CNES is making significant contributions with camera systems for spatial orientation and exploration on the surface as well as for investigating the mechanical properties of the ground. In addition, CNES is developing the rover's central service module, including the onboard computer and the power and communication system. Final integration and testing will take place at CNES in Toulouse. After the launch of the MMX mission, the rover will be operated by control centers of DLR MUSC in Cologne and CNES in Toulouse (France).

The mission sequence

MMX is expected to take off from the Japanese launch site in Tanegashima on an H-3 launcher in 2026. After a flight time of around one year, MMX will reach Mars and enter its orbit. The eight scientific instruments of the exploration module will then begin mapping and characterizing the surfaces of Phobos and Deimos. The rover is scheduled to land on Phobos in 2029. The rover will be lowered from a height of 40 to 100 meters above the surface. After landing - and probably a few small bounces - it will stand up on its own and then be ready for use. The measurement phase will then begin, lasting around three months, during which the rover will travel to various targets of interest for scientific analysis.

Back to earth

At the end of the mission, the mother probe will collect soil samples, taking into account the knowledge gained by the rover, which will be brought back to Earth with the return module. They are due to arrive there in 2031 for further analysis in terrestrial laboratories. The Japanese space organization JAXA is predestined for such a challenging task: most recently in 2020, the "Hayabusa 2" mission succeeded in bringing material from the asteroid Ryugu back to Earth. DLR and CNES were already involved in Hayabusa 2 with the MASCOT lander.

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