A lot of classic science fiction written between the 1600s-1900s features galleons that ascend to the heavens and sail through space. To people of that era, ocean-going ships were the ultimate symbol of freedom and the perfect image for their imaginary spaceships. It turns out they were on to something! NASA is leading world research on solar sails, a low-cost propulsion method in which giant sails catch the solar wind. In other words, we're inventing star-surfing. Not too shabby, NASA.