photons. Japan's solar sail-equipped IKAROS probe has recorded its first propulsion derived from the force of sunlight rays hitting its tender surface. The force generated is a truly minuscule 1.12 millinewtons, but that can go a long way (literally) in a frictionless environment like space. The kite's sails also soak up Sol's emitted light to generate electricity, making the most out of the one resource available to it. So now that we've figured out how to do all that, shall we get started on colonizing Mars or what?