of the Earth due to gravitational effects from the Moon, requires the small autonomous flyers to be capable of maneuvering themselves to hold position. A suggested solution is to place mirrors capable of rotation on the surface of the flyers. By using the solar radiation pressure on the mirrors as solar sails and tilting them in the right direction, the flyer will be capable of altering its speed and direction to keep in position. Such a group of sunshades would need to occupy an area of about 3.8 million square kilometers if placed at the L1 point. The deployment of the flyers is an issue that requires reusable rockets. With a 100t LEO rocket, a single launch per day would allow the release of the required number of sails within 20 years, at a goal of 1% reduction. Even so, it would still take years to launch enough of the disks into orbit to have any effect. This means a long lead time. Roger Angel of the University of Arizona presented the idea for a sunshade at the U.S. National Academy of Sciences in April 2006 and won a NASA Institute for Advanced Concepts grant for further research in July 2006. Creating this sunshade in space was estimated to cost in excess of US$130 billion over 20 years with an estimated lifetime of 50-100 years. Thus leading Professor Angel to conclude that "the sunshade is no substitute for developing renewable energy, the only permanent solution. A similar massive level of technological innovation and financial investment could ensure that. But if the planet gets into an abrupt climate crisis that can only be fixed by cooling, it would be good to be ready with some shading solutions that have been worked out." A more recent design has been proposed by Olivia Borgue and Andreas Hein in 2022 proposing a distributed sunshade with a mass on the order of 100,000 tons. One Fresnel lens Several authors have proposed dispersing light before it reaches the Earth by putting a very large lens in space, perhaps at the L1 point between the Earth and the Sun. This plan was proposed in 1989 by J. T. Early. In 2004, physicist and science fiction author Gregory Benford calculated that a concave rotating Fresnel lens 1000 kilometres across, yet only a few millimeters thick, floating in space at the point, would reduce the solar energy reaching the