It’s a core requirement for return flights to Earth in the “Mars Direct” model that SpaceX has based its plan on. But the SpaceX plan doesn’t require the astro

It’s a core requirement for return flights to Earth in the “Mars Direct” model that SpaceX has based its plan on. But the SpaceX plan doesn’t require the astronaut return on the first Synod, or on any fixed schedule. The first to land will have ice mining and in situ fuel generation equipment, but we have no idea if they will work, or work at a level that will generate enough fuel for return flights in reasonable time periods. Which is fine. Succeeding missions will bring equipment to address the shortcomings of the first, until they are producing fuel effectively for return missions. The first astronauts are unlikely to be able to return in the first two years, it might take ten. But they will happily sign up for this plan because it gets them to Mars decades sooner.