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
Phobos (moon) presence of voids and indicate that it is not a solid chunk of rock but a porous body. The porosity of Phobos was calculated to be 30% ± 5%, or a quarter to a third being empty. Phobos has been photographed in close-up by several spacecraft whose primary mission has been to photograph Mars. The first was "Mariner 7" in 1969, followed by "Viking 1" in 1977, "Mars Global Surveyor" in 1998 and 2003, "Mars Express" in 2004, 2008, and 2010, and "Mars Reconnaissance Orbiter" in 2007 and 2008. On August 25, 2005, the "Spirit" rover, with an excess of