The Solar-Sail Option: From the Oceans to Space

In the previous chapters, we described the space rocket engines, how they work, their role in past and current spaceflight, and their limitations. We have also shown that the rocket is not the only propulsion type that could be employed in space. Among the types of space propulsion currently under investigation, one is particularly promising: the solar sail. This propulsion mode is not conceptually new, even though only recent technology gives it a good chance to make a quality jump in spaceflight. Its principles and how to efficiently use a sail vehicle could be understood better by reviewing what happened about four millennia ago on the seas and by referring to the progress of physics in the 19th and 20th centuries.