Moons of Mars formed a large moon. Gravitational interactions between this moon and the outer ring formed Phobos and Deimos. Later, the large moon crashed into Mars, but the two small moons remained in orbit. This theory agrees with the fine-grained surface of the moons and their high porosity. The outer disk would create fine-grained material. While many Martian probes provided images and other data about Phobos and Deimos, only few were dedicated to these satellites and intended to perform a flyby or landing on the surface. Two probes under the Soviet Phobos program were successfully launched in 1988, but neither conducted the
Mars One 2013. Canadian former astronaut Julie Payette said during the opening speech for an International Civil Aviation Organization conference that she does not think Mars One "is sending anybody anywhere". In January 2014, German former astronaut Ulrich Walter strongly criticized the project for ethical reasons. Speaking with Tagesspiegel, he estimated the probability of reaching Mars alive at only 30%, and that of surviving there more than three months at less than 20%. He said, "They don't care what happens to those people in space... If my tax money were used for such a mission, I would organize a protest." Space tourist