We have absolutely no experience shielding people from solar winds and cosmic radiation in any way that would be meaningful for an interplanetary journey. Even

We have absolutely no experience shielding people from solar winds and cosmic radiation in any way that would be meaningful for an interplanetary journey. Even the ISS is benefiting from Earth's magnetosphere and atmosphere. We have a few vague ideas: * Thick plating. (How? Not like we can launch it, so we'd have to build the space craft in space using materials mined from e.g the moon or asteroids) * An artificial magnetosphere, which researchers are still doing feasibility studies on. But there'd be a litany of challenges there as well, such as figuring out how to design it so that we don't see deleterious effects on electronics or people. Moon jaunts were short enough that it didn't matter, but anything interplanetary will need this challenge to be solved lest we want our explorers to suffer excruciatingly painful deaths.