Nautilus is a revolutionary space telescope concept that builds on a novel technology – engineered material diffractive-transmissive optical elements – to overcome the greatest limitations of space telescopes: non-scalable primary mirrors. By providing large but ultra-light telescope apertures, the Nautilus technology will enable the launch of a large fleet of identical telescopes. With a light-collecting power equivalent to a 50m diameter mirror Nautilus will be capable of surveying thousands of earth-sized habitable zone planets for atmospheric signatures of life.