One of the most difficult things about space travel is building a craft capable of traveling to far away parts of the solar system or galaxy. The cost of these missions is astronomical, (no pun intended) especially when you talk about traveling outside the solar system. Perhaps we could change that. In order to travel effectively to far away parts of the galaxy we must find a way to achieve a speed that is a significant fraction of the speed of light. One way to do that is by using solar sails. Solar sails use what is sometimes called “solar wind” to propel space craft. Solar wind is a kind of radiation given off by stars that is capable of exerting a physical force on objects. In fact, solar wind is the reason Mars no longer has an atmosphere, as it push all the atoms out of Mars gravitational pull.

Solar sails would be ideal because, first of all the would exert an acceleration force on a space craft, which would maintain that speed given the lack of friction in space, and secondly because solar wind, unlike rocket fuel, is free. by harnessing the suns solar wind we could easily accelerate a spacecraft to another star, where it would accelerate even more. This process would continue until the ship had reached a significant fraction of the speed of light.

Solar sails may seem like an incredibly new idea, but the idea has in fact been around for hundreds of years. Johan Kepler first eluded to the idea in the early 1600’s in a letter to Galileo after he discovered that comet tails are caused by solar radiation. He said that it may one day be possible to harness this energy for the purpose of space travel.

There are a few draw backs to solar sails however. For one thing, they would have to be incredibly massive to accumulate enough energy from solar wind to accelerate them a significant amount. Secondly, building something this large would be incredibly expensive, perhaps even more so than fueling a rocket. However, when it comes time to put human beings on long space journeys, unless some new invention comes to the fore front, I believe solar sails provide the best option.