How carrying enough water to make return-trip propellant simplifies a Starship mission to Mars

The idea of a human mission to explore Mars has been studied repeatedly over the past 75 years. More than 1,000 piloted Mars mission studies were conducted inside and outside NASA between about 1950 and 2000. Many were the product of NASA and industry study teams, while others were the work of committed individuals or private organizations. I compiled a history of human mission studies through 2023. Essentially all of these mission design concepts were deemed impractical but now, if the SpaceX Starship proves flightworthy, new possibilities could finally emerge as the constraints on space travel change.

All of these studies were carried out in the era of constrained mass. Launch costs were high and minimizing mass sent to space was the main driver for mission design. To reduce mass, m