A recent study submitted to Acta Astronautica and currently available on the arXiv preprint server explores the potential for using aerographite solar sails for traveling to Mars and interstellar space, which could dramatically reduce both the time and fuel required for such missions.
It can’t really be scaled up to human carrying capacity. The density of solar wind is very sparce. Any sail large enough to accelerate a human habitat would itself become too heavy.
So I guess we’re back to the drawing board.
Do we got those nuclear engines kicking around anywhere?