NASA’s budget has been cut. The last space shuttle has yet to take off (boy, is IT late). But, we still hope to send exploratory vessels to other planets. The problem is getting the probes to their destination reliably- when the distance is long. One possibility relies upon Friedrich Zander’s proposition (1924) that we can use the thrust from photons (light energy) and no other fuel. His hypothesis was based upon Einstein’s theory (which was confirmed by Peter Lebedev’s experiments) that photons have momentum, so that when absorbed by or reflected from a surface, there would be “radiation pressure”. A large sail may have very little acceleration, but given long time periods, the sail would generate reasonable speeds; as these sails are further from gravitational fields, their acceleration capability becomes viable.