Tradeoff Study of High Altitude Solar Reflector Concepts

A direct solution to Global Warming would be to reflect a part of sunlight back into Space. A system tradeoff study is being developed with three of the concepts that are being evaluated as long-endurance high-altitude reflectors. The first concept is a high aspect ratio solar powered flying wing towing reflector sheets. This concept is named “Flying Carpet”. Second is a centrifugally stretched high altitude solar reflector (CSHASR). The CSHASR has 4 rotors made of reflector sheets with a hub stretching to 60 percent of the radius, held together by an ultralight quad-rotor structure. Each rotor is powered by a solar-electric motor. A variation on this concept, forced by nighttime descent rate concerns, is powered by tip-mounted solar panels and propellers with some battery storage augmenting rotational inertia as well as energy storage. The third concept is an Aerostatically Balanced Reflector (ABR) sheet, held up by hydrogen balloons. A set of co-axial counter-rotating rotors provides trim, directional control and migration with the summer Sun. This concept also offers the ability to hold up the reflector at arbitrary orientations to achieve maximum reflection, normal to the slanted rays of the polar summer sun. This paper presents concept evaluation and comparisons, explaining the concepts and high-level features of each concept in this extreme and little-explored regime of rotorcraft aeromechanics as well as aerostatics.