The sun gun or heliobeam was a theoretical orbital weapon.
The Scottish mathematician John Napier proposed such a device. In his book Secrete Inventionis (1596), he published details of a giant mirror to burn enemy ships by focusing the sun's rays on them.
In 1929, the German physicist Hermann 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.
Later during World War II, a group of German scientists at the German Army Artillery proving grounds at Hillersleben began to expand on Oberth's idea of creating a superweapon that could utilize the sun's energy. This so-called "sun gun" would be part of a space station 8,200 kilometres (5,100 mi) above Earth. The scientists calculated that a huge reflector, made of metallic sodium and with an area of 9 square kilometres (3.5 sq mi), could produce enough focused heat to make an ocean boil or burn a city. After being questioned by officers of the United States, the Germans claimed that the sun gun could be completed within 50 or 100 years.
Uses in popular culture
In the film Die Another Day, the twentieth installment in the James Bond series of films, the primary antagonist of the film, fictional British billionaire Gustav Graves, constructs an orbital sun gun code named "Icarus" for the use of cutting a path through the Korean Demilitarized Zone and allowing North Korean troops to invade South Korea. The device was disabled after its control console is destroyed.
- Archimedes heat ray, a purported device from antiquity which weaponized the sun's rays