June 2018 saw the first participatory public debate on the ethics of space exploration, organized by Space’ibles, the futures monitoring organization of the French National Centre for Space Studies (CNES). Futuribles joined in with this exercise, using short fictions that presented various possible future scenarios in the space field – not all of them with the same consequences at the ethical level – to stimulate thinking. Daniel Kaplan, who took part in this exercise, here outlines the various fictions proposed: ‘Mars at all costs’, ‘The Guardians of Space’, ‘Earthmen first’ and ‘Launchpad for the Ark Starship’. He also shows what is to be gained from the use of fiction to stimulate debate on the ethics of space conquest and exploration. He closes by presenting the first findings of this participatory debate and the potential follow-up to it.