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
Terraforming of Mars have risen high enough for seas and rivers to form. The 1993 space trading and combat game "", as well as its sequels "" (1995) and "Elite Dangerous" (2014), feature a terraformed Mars. The 1997 PC Real-time strategy game "Dark Colony" is based on a human-terraformed Mars, featuring a war between the colonizing humans and invading aliens of various life forms, with much use of biological warfare. The aliens try to colonize the terraformed planet for its resources. The 2009 video game "" is set on a partially terraformed Mars, in which human beings are able to walk and breathe