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{{short description|Theoretical orbital weapon}}
{{distinguish|Stun gun (disambiguation){{!}}Stun gun}}
The '''sun gun''' or '''heliobeam''' is a theoretical [[orbital weapon]], which makes use of a [[concave mirror]] mounted on a [[satellite]], to concentrate sunlight onto a small area at the Earth's surface, destroying targets or killing through heat.

== History ==
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.<ref name="Time">{{cite journal|date=July 9, 1945|url=http://content.time.com/time/subscriber/article/0,33009,852344-1,00.html|title=Science: Sun Gun|journal = [[Time Magazine]]}}</ref>

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 [[Wunderwaffe|superweapon]] that could utilize the sun's energy. This so-called "sun gun" (''Sonnengewehr'') would be part of a space station {{convert|8200|km}} above Earth. The scientists calculated that a huge reflector, made of metallic [[sodium]] and with an area of {{convert|9|sqkm|ha mi2}}, could produce enough focused heat to make an ocean boil or burn a city.<ref name="Time"/> After being questioned by American officers, the Germans claimed that the sun gun could be completed within 50 or 100 years.<ref name="Time"/><ref name="Life">{{cite journal|date=July 23, 1945|url=https://books.google.com/books?id=30kEAAAAMBAJ&pg=PA78|title=The German Space Mirror|journal = [[Life Magazine]]|page=78}}</ref>

With the deployment and validation of [[Satellite_constellation|satellite 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 concentrate [[solar irradiance]] and aim it at a target.<ref>{{Cite web |first=David |last=Shiga |title=Space mirrors could create Earth-like haven on Mars |url=https://www.newscientist.com/article/dn10573-space-mirrors-could-create-earth-like-haven-on-mars/ |access-date=April 23, 2023|website=New Scientist |language=en-US |archive-url=https://web.archive.org/web/20230423052858/https://www.newscientist.com/article/dn10573-space-mirrors-could-create-earth-like-haven-on-mars/ |archive-date=April 23, 2023 |url-status=live}}</ref>

== See also ==
* [[Archimedes' heat ray]], a purported device from antiquity which weaponized the sun's rays
* [[Concentrated solar power]]
* [[Space mirror (climate engineering)]]
* [[Space-based solar power]]
* [[Solar furnace]]

==References==
{{reflist}}

[[Category:Research and development in Nazi Germany]]
[[Category:Space weapons]]
[[Category:Weapons of mass destruction]]
[[Category:Solar energy]]
[[Category:Proposed weapons]]