Solar Sails
"Ships and Sails proper for heavenly breezes should be fashioned…"
-Johannes Kepler, 1609
Kepler, nearly four hundred years ago, observed that a comet always has its tail facing away from the sun. This led him to conclude that light emanating from Sun exerts a force that pushes the comet’s tail away.
If the sun can push the comet’s tail around, why can’t we use it to move spacecrafts around? The answer is YES! We can employ large mirrors in the effort to propel a spacecraft using sunlight. However, this would require a huge amount of light. In retrospect, a one square kilometer mirror, only one micron thick, would have to be used to be anywhere close to being as efficient a travel device as some of the other technologies. However, if such a solar sail could be made, the idea stands as another possibility and road for us to try in our effort to find efficient travel to Mars.