Don't use drag use gravity... http://en.wikipedia.org/wiki/Gravity_assist http://en.wikipedia.org/wiki/Gravity_assist Basically you loop in front of a planet,

Don't use drag use gravity... http://en.wikipedia.org/wiki/Gravity_assist http://en.wikipedia.org/wiki/Gravity_assist Basically you loop in front of a planet, and then it slingshots you back to the Sun. Voila... done.