The convoluted history of the Russian Space Mirror on Youtube. A 1930s Nazi idea for a wonder-weapon ended up as a failed prototype for winter sunlight across the USSR.

Good footage of the prototype vehicles (the Russians had a good few tries at the idea), but the presentation is marred by the narrator’s cavalier attitude to technology and history, regarding (non?)-adjustable focal lengths and how Archimedes died. (As several commentators point out.)