Thesun gun orheliobeam is a theoreticalorbital weapon, which makes use of aconcave mirror mounted on asatellite, to concentrate sunlight onto a small area at the Earth's surface, destroying targets or killing through heat.
In 1929, the German physicistHermann Oberth developed plans for a space station from which a 100-metre-wide concave mirror could be used to reflect sunlight onto a concentrated point on the earth.[1]
Later, duringWorld War II, a group of German scientists at the German Army Artillery proving grounds atHillersleben began to expand on Oberth's idea of creating asuperweapon that could utilize the sun's energy.[2] This so-called "sun gun" (Sonnengewehr) would be part of a space station 8,200 kilometres (5,100 mi) above Earth. The scientists calculated that a huge reflector, made of metallicsodium and with an area of 9 square kilometres (900 ha; 3.5 sq mi), could produce enough focused heat to make an ocean boil or burn a city.[1] After being questioned by American officers, the Germans claimed that the sun gun could be completed within 50 or 100 years.[1][3] Evidence that Japan was also attempting to develop a death ray was uncovered by American forces.[4][5][6]
With the deployment and validation ofsatellite mega-constellations, their use as a sun gun has also been proposed. Instead of a vast individual mirror, hundreds of low cost reflectors could in theory be synchronized to concentratesolar irradiance and aim it at a target.[7]