Up until the age of the steam engine, sails were the primary means of harnessing natural energies to propel craft. Rather than power against the laws of physics, sailors of a different time simply unfurled massive canvas sheets allowing forces that in a simple breath are weak, but given enough space to absorb could move massive ships more efficiently than fifty oarsmen across vast distances. With the creation of the steam engine, many sailors thought their art would be lost forever. But now Japan’s IKAROS is changing that. IKAROS will be the first entirely solar powered test vehicle designed for interplanetary travel.
The IKAROS will launch as a stowaway on the Venus Project and detach, unfurling its sail. As it spreads its wings, it will be so lightweight that it will be able to travel by virtue of the momentum generated from photons being reflected off its surface. As photons bounce off the reflective surface they propel the craft forward. The unfurling of the wings will come from its rapid propelling which will send out weights attached to strings to pull the wings outward. The final stages will be correcting its position and to stop spinning. Additionally, solar panels have been placed on the surface to show that at some point in the future the craft could indeed house a power supply and even contain additional electrical circuits that could gather data, assist further in continuously ensuring it maintains a steady trajectory, and (if given a large enough sail) could even power life support for a small crew on their journey. Since there is no carried fuel, the craft can be far lighter once it gets off the Earth.
Of course those familiar with the story of Icarus, who shares a strikingly similar name in spelling, and essentially the same name in pronunciation, will recall the story of the boy who flew too close to the sun and lost his life when his wings melted as he and his father attempted to escape their prison. The myth has been used as an allegory for man’s hubris and ambition without taking into consideration the limitations of his own invention. We can only hope IKAROS will not meet some sort of poetic end similar to its namesake.
The IKAROS is expected to travel for six months through space before Earth loses contact with it. The premise has been used before to help move satellites and explorer modules into orbit with other planets, moons, and asteroids, but there has never been a project ambitious enough to make the solar sail the sole means of propulsion.
And IKAROS isn’t the only model on the table now for solar sailing. California has designed its own system, the LightSail-1, which it hopes to put into space within a year. Countless other design systems are being proposed every month. Solar sails seem to be a cost effective way of getting lightweight equipment such as simple sensor systems to other worlds. this is yet another technological achievement that shows mankind’s destiny is to reach into the stars.