Earth by approximately 0.5% to 1%. The cost of such a lens has been disputed. At a science fiction convention in 2004, Benford estimated that it would cost about US$10 billion up front, and another $10 billion in supportive cost during its lifespan. One diffraction grating A similar approach involves placing a very large diffraction grating (thin wire mesh) in space, perhaps at the L1 point between the Earth and the Sun. A proposal for a 3,000 ton diffraction mesh was made in 1997 by Edward Teller, Lowell Wood, and Roderick Hyde, although in 2002 these same authors argued for blocking solar radiation in the stratosphere rather than in orbit given then-current space launch technologies. Spacecraft sunshades The James Webb Space Telescope (JWST) infrared telescope has a layered sunshade to keep the telescope cold. For spacecraft approaching the Sun, the sunshade is usually called a heatshield. Notable spacecraft [designs] with heatshields include: Messenger, launched 2004, orbited Mercury until 2015, had a ceramic cloth sunshade Parker Solar Probe (was Solar Probe Plus), launched 2018 (carbon, carbon-foam, carbon sandwich heatshield) Solar Orbiter, launched Feb 2020 BepiColombo, to orbit Mercury, with Optical Solar Reflectors (acting as a sunshade) on the Planetary Orbiter component. See also References External links Climate change mitigation Terraforming Climate engineering