Stephan, Sara, Henri, and Beatriz are four people who, like tens of thousands of applicants from all over the world, answered an advert for people who’d like to visit Mars. There’s only one catch: this mission is one-way only. The initiative is one of love and hate, admiration and controversy. Since applications opened in 2013, Mars One receives tens of thousands of testimonials from followers every day, but their enthusiasm is matched by others’ horror at the suicidal idea.