Japan's Martian Moons eXploration (MMX) Mission: International Partnership FriendsofNASA.org: How did Mars’ moons Phobos and Deimos form? The Martian Moons eXploration (MMX) Mission aims to answer this very question. Developed by the Japan Aerospace Exploration Agency (JAXA), the spacecraft will explore Phobos from orbit and collect samples from its surface. On board MMX will be the IDEFIX rover—a collaboration between the German Aerospace Center (DLR) and the French space agency, Centre nationa