Despite several attempts over the past decades, Phobos and Deimos are yet to be studied in detail. Scientists are still debating their origin: Are they the result, like our own Moon, of a giant impact between Mars and another celestial body in the primeval solar system, or are they asteroids captured into the red planet’s orbit? The Japan Aerospace Exploration Agency (JAXA) is undertaking the MMX mission to answer this question, gain new insights into Phobos and Deimos and understand how they formed and evolved.

MMX consists of three separate modules, each with a specific purpose. After lifting off from Japan in September 2024, the propulsion module will convey the other two to Mars’ moons in less than a year. The second module is composed of a robotic probe and a small French-German rover. The probe will land on Phobos to collect 10 grams of material after surveying it from a quasi-orbit. Once it has set down the rover and obtained samples on Phobos, the probe will execute a series of flybys of the smaller moon Deimos. It will then release the third module that will bring back the samples to Earth inside a return capsule in 2029.

The main mission will be carrying a suite of 13 scientific instruments (including the rover), with the goal of mapping and characterizing the moons’ surface at high resolution in order to determine their chemical and mineralogical make-up, as well as observing storms and clouds on Mars. The MIRS instrument (MMX InfraRed Spectrometer) will characterize the moons’ mineral composition and analyse Mars’ atmosphere. It will also help teams to select landing sites for MMX.

In partnership with JAXA, CNES is contributing to the MMX mission in three ways. First, it is studying flight trajectories and dynamics for the cruise phase and will possibly be involved in flight operations. Second, it is involved in the mission’s science with the MIRS near-infrared imaging spectrometer on the robotic probe. And third, it is working with teams at the German space agency DLR to build the rover and its four instruments that will attempt the unique feat of driving on Phobos, where gravity will be some 1,800 times weaker than on Earth.