Wernher von Braun proposed a wet workshop concept for launch on the Saturn V. His design modified the S-II second stage of the Saturn V stack to allow it to be used as living space once reaching orbit. Since the S-IC lower stage of the Saturn V cannot reach orbit on its own, the S-II would have to fire, and then vent out any remaining propellant once it reached orbit. To allow this, the floors of the station would be made of an open grid which allowed the propellant to pass through easily to the piping at the bottom of the tanks. The structure also presented convenient hand and footholds.