SpaceX Starship can return from Mars without surface refilling at https://www.youtube.com/watch?v=u55zpE4r-_Y
The engineering design and manufacturing costs for atomic power are a lot less than the cost of hauling chemical or solar panels to Mars. Do the numbers and see what it is worth to spend on lightweight atomic power units and technologies.
A few ten million dollars buys a lot of global Internet collaboration, and there are a lot of people who have no atomic or nuclear jobs now scattered all over earth. Get them working together and sharing in one project, not wasting their time on earth problems, they can give designs for most all applications. Then do the numbers.
Do the same for all the required technologies, and don’t waste people’s time watching video pictures and works. Let the work on the real models and data together. Don’t make hundreds of thousands or tens of millions reinvent the basic space travel economic calculators.
Mars and space and moon have lots of space far from humans for remote atomic power. Apply those high energy density sources to the space portion of the travel, and the masses are less. Put them on the surface and even places far from water can process oxides to separate for oxygen and metals. Take a look, do the numbers. Process oxides for oxygen and metals and glasses, and anywhere on the moon can be sustainable.
Shorter trips with distant atomic engines is probably a lot less radiation exposure than long trips exposed to space radiation sources, and a LOT less food and life support, and human weightlessness.
Richard Collins, Director, The Internet Foundation