Phobos And Deimos & Mars Environment Phobos And Deimos & Mars Environment Phobos And Deimos & Mars Environment (PADME) is a low-cost NASA Mars orbiter mission concept that would address longstanding unknowns about Mars' two moons Phobos and Deimos and their environment. The PADME mission competed for Discovery Program funding, but lost to the Psyche and Lucy missions. The mission is led by Anthony Colaprete (Principal Investigator). Other principals include Pascal Lee (Deputy Principal Investigator) and Butler Hine (Project Manager). The origin of Mars' satellites, which were discovered by astronomer Asaph Hall, remains unknown. PADME would advance the scientific understanding of the origin of Phobos and
Solar System icy objects. Astronomers sometimes informally divide this structure into separate regions. The inner Solar System includes the four terrestrial planets and the asteroid belt. The outer Solar System is beyond the asteroids, including the four giant planets. Since the discovery of the Kuiper belt, the outermost parts of the Solar System are considered a distinct region consisting of the objects beyond Neptune. Most of the planets in the Solar System have secondary systems of their own, being orbited by planetary objects called natural satellites, or moons (two of which, Titan and Ganymede, are larger than the planet Mercury), and, in