Dennis Tito, a spritely 72-year-old American, wants to send people to the planet Mars. The multi-millionaire has set up the Inspiration Mars Foundation and plans to send a couple on a 501-day round trip to the red planet in 2018.
Space is something Tito knows well. He was the first space tourist, paying Russia a reported $20 million (€15.4 million) for a ticket to the International Space Station in 2001. He and others, including the entrepreneur Richard Branson, are leading efforts to commercialise space travel.