Mars to Stay to 30, thereby beginning a Martian settlement. Since the Martian surface offers all the natural resources and elements necessary to sustain a robust, mature, industrialized human settlement—unlike, for example the Moon—a permanent Martian settlement is thought to be the most effective way to ensure that humanity becomes a space-faring, multi-planet species. Through the use of digital fabricators and in vitro fertilisation it is assumed a permanent human settlement on Mars can grow organically from an original thirty to forty pioneers. A Mars to Stay mission following Aldrin's proposal would enlist astronauts in the following timeline: As Aldrin has said, "who
Mars to Stay the astronauts from the surface of Mars is one of the most difficult parts of a Mars mission, the idea of a one-way trip to Mars has been proposed several times. Space activist Bruce Mackenzie, for example, proposed a one-way trip to Mars in a presentation "One Way to Mars – a Permanent Settlement on the First Mission" at the 1998 International Space Development Conference, arguing that since the mission could be done with less difficulty and expense if the astronauts were not required to return to Earth, the first mission to Mars should be a settlement, not a visit.