Dennis Tito, the American entrepreneur who paid $20 million in 2001 for a trip to the International Space Station, spoke before a House subcommittee on space today to outline his plans for reaching Mars. According to Tito, the “Inspiration Mars” endeavor will be a fly-by mission that’ll take two astronauts 808 million miles from Earth to Mars and back again in 501 days. And he’ll need more than $1 billion to do it. The plan works within a narrow timeline that takes advantage of a rare alignment in Earth and Mars’ orbits. According to Tito’s written testimony, the launch will need to take place between Christmas 2017 and January 5th, 2018 to ensure a speedy trip. So to pull that off, Inspiration Mars will need complete cooperation from NASA — the two-man crew aboard the Inspiration Mars’ commercial craft will need the space agency’s huge Space Launch System (SLS) rocket to propel them there. The SLS rocket is still under development.