If humans are ever to reach deep space, there will need to be some revolutionary changes in transport. Dreamt up at the â€¦beginning of last century, solar sails are now moving a step closer to reality, as one of the most feasible ways of travelling into deep space. They are lightweight panels made from reflective material that act like the sails of a boat. Rather than using wind, the sails are actually propelled by light. Unbelievable as it may seem, the stream of light particles (called photons) emitted from the Sun are strong enough to push a mini-spacecraft right out of the Solar System and beyond into interstellar space.