Early solar sails were much too heavy for designing a practical solar sailing vehicle. Materials need to be lightweight and highly reflective while being able to tolerate extreme temperatures. The giant sails currently being tested are made of very lightweight, reflective materials that are more than 100 times thinner than an average sheet of stationery. It is specifically an aluminized, temperature-resistant material.

Another solar sail being tested is made of aluminum-reinforced Mylar which is approximately one fourth the thickness of a one-ply plastic trash bag. The reflective nature of the material is critical since the photons that bounce off the materials gently push the sail along by transferring momentum to the sail.