Human mission to Mars propellant from the Martian Atmosphere. This proposal drew on concepts developed by the former "Case for Mars" conference series. Over the next decade, Zubrin developed it into a mission concept, Mars Direct, which he presented in a book, "The Case for Mars" (1996). The mission is advocated by the Mars Society, which Zubrin founded in 1998, as practical and affordable. In 1991 in Toulouse, France, the International Space University studied an international human Mars mission. They proposed a crew of 8 traveling to Mars in a nuclear-powered vessel with artificial gravity provided by rotation. On the surface, 40 tonne habitats
The Gods of Mars the two Viking missions which found a dead, frozen world where water does not exist in a fluid state. The Valley of Dor, with the ring of cliffs around it and Sea of Korus within it, is placed in a mile-deep crater at Mars' South Pole. However, Burroughs makes a mistake in that he has the sun rise in the east and set in the west as elsewhere in the planet, and the moons are visible from the Valley. In reality, at the South Pole, Mars' moons would not be seen, and the sun would not rise in the east